A SURVEY OF PARASITIC HELMINTHS IN HORSES FROM 

COMMUNAL FARMS IN THE NORTHEASTERN FREE STATE 

PROVINCE OF SOUTH AFRICA 

BY 

Flatha Euginia Sarah Masangane 

A thesis submitted in fulfillment for a Degree of Master of Science (M.Sc.) 

in Zoology (Parasitology) 

Faculty of Natural and Applied Sciences 

School of Life Science 

Parasitology Research Program 

University of the Free State 

(Qwa-Qwa Campus) 

Supervisor: Prof. P.A. Mbati 

Co- Supervisor: Dr. S.M. Malatje 

2004 



DECLARATION 

I, Flatha Euginia Sarah Masangane, hereby declare that this thesis is my 

original work and has not been presented for a degree in any other university 

Fla!:2~Sa.rah Masangane 

This thesis has been submitted for a M.Sc. degree in Zoology (Parasitology) with 

our approval as University supervisors 

Prof. P.A. Mbati 

Dr. S .M. Malatj e 

(Co-supervisor) 

ii 



DEDICATION 

This thesis is dedicated to my little boy, Siyabonga and my family (mother, two 

young sisters and young brother) for the love and support they always gave me, 

and above all to our Almighty GOD for the strength He has given me through 

difficult times of my studies and life. 

Ill 



ACKNOWLEDGEMENTS 

I am greatly indebted to my supervisor Prof. P.A. Mbati and Dr. S.M. 

Malatje for their encouragement, understanding and guidance. I would like 

to acknowledge the support and assistance provided by my collegues in the 

Parasitology Research Program: Fumane Nyaile, Makhosazana Motloang, 

Edith Diaho, Kagiso Mogaswane, Sibusiso Mtshali and Motseki 

Hlatshwayo; and from the Herpetology Research group: Tankiso Matla, 

Lucas Thibedi and Phomolo Mashinini. I would like to express my deepest 

appreciation for assistance and support I received from Oriel Thekisoe. 

I am grateful to members of the library and transport sections of University 

of the Free State Qwa-Qwa campus for their assistance. To all the farmers 

who allowed me to use their horses goes my deepest gratitude. I would like 

to thank Dr. Peter Njuho of the University of the Natal (Pietermaritzburg) 

for his assistance in data analysis. 

I would like to express my appreciation for the training that I received from 

Ms. Lynne Michael and Mr. Johan Van Rensburg from Onderstepoort 

Veterinary Institute (OVI) in Pretoria, Prof. Tammie Krecek from University 

of Pretoria and Dr. Sonja Matthee from the University of Stellenbosch. 

This project is based on research concept developed by Prof. P.A. Mbati and 

received financial support from grants made available to him: University of 

the North Qwa-Qwa Campus Senate Research Grant 4521 and the National 

Research Foundation (GUN 2039188). 

iv 



TABLE OF CONTENTS 

CONTENTS PAGE 

Title 1 

Declaration 11 

Dedication 111 

Acknowledgements 1v 

Table of contents v 

List of figures 1x 

List of tables x 

Abstract x1 

CHAPTERl 

1. INTRODUCTION AND LITERATURE REVIEW 1 

1.1 Helminth parasites of horses 1 

1.1.1 Phylum Nematoda 1 

1.1.1.1 Example of nematodes species that infect horses 2 

1.1.2 Phylum Platyhelminthes 7 

1.1.2.1 Class Trematodes 7 

1.1.2.2 Class Cestodes 9 

1.2 Ticks as a parasites of veterinary important for horses 13 

1.2.1 Phylum Athropoda 13 

1.2.1.1 Example of tick species that infect horses 14 

1.3 Problems Facing Horse Owners 15 

1.3. I Control of helminth parasites 16 

1.3.2 Managing ecto-parasites (ticks) on horses 17 

1.3.3 Management of horses 17 

1.4 Socio-economic factors 21 

V 



CHAPTER2 

2. OBJECTIVES OF THE STUDY 

2.1 Rationale 

2.2 General Objectives 

2.3 Specific Objectives 

CHAPTER3 

3. MATERIALS AND MAETHODS 

3.1 Description of study area 

3 .2 Collection of blood, ticks and fecal samples 

24 

24 

25 

25 

26 

26 

28 

3.3 Fecal worm egg counts 28 

3.3.1 McMaster technique (Reinecke, 1983) 32 

3.3.2 Visser sieve technique (Malan and Visser, 1983) 33 

3.3.3 Centrifugation/ flotation technique (Beroza et al., 1986) 34 

3 .4 Fecal cultures from horses 3 5 

3.5 Blood sample collection and PCV determination (Michael, 1999) 

3.6 Questionnaire survey 

3. 7 Data presentation 

CHAPTER4 

37 

37 

38 

4. RESULTS 39 

4.1 Helminth distribution, diversity and abundance in horses 39 

4.2 Seasonal Dynamics of helminth species isolated from horses 43 

4.3 Larval cultures 43 

4.4 Seasonal Dynamics of ticks species isolated from horses 43 

vi 



4.5 Questionnaire survey 48 

4.5.1 Demography 48 

4.5.2 Management of sick animals 50 

4.5.3 Nutrition of horses 51 

4.5.4 Breeding of horses 51 

4.5.5 Management of horses 51 

CHAPTERS 

5. DISCUSSION 54 

5.1 Total fecal egg count 54 

5.2 Strongyle egg count 54 

5.3 Parascaris equorum egg count 55 

5.4 Oxyuris equi egg count 55 

5.5 Larval cultures 55 

5.6 Packed cell volume (PCV) 56 

5.7 Monthly and seasonal averages 56 

5.7.l Parascaris equorum egg count 56 

5.7.2 Oxyuris equi egg count 57 

5.8 Ticks pasitizing horses 57 

5.9 Condition Scoring 58 

5.10 Questionnare 59 

CHAPTER6 

6. CONCLUSION 61 

vii 



CHAPTER 7 

7. REFERENCES 65 

Appendix 1 81 

viii 



LIST OF FIGURES 

Figure 1: Map showing the location of study site, Kestell in the north eastern 

Free State Province South Africa 27 

Figure 2: Diagrams of areas palpated to estimate body fat and condition 

score 28 

Figure 3: EPG values ofhelminthic species of horses in Kestell (Farm 1) 

44 

Figure 4: EPG values ofhelminthic species of horses in Kestell (Farm 2) 

45 

Figure 5: Mean monthly male and male Rhipichephalus burdens on horses 

on Farm 1 46 

Figure 6: Mean monthly male and male Rhipichephalus burdens on horses 

on Farm 2 47 

Figure 7: The proportion of domestic animals owned by farmers 49 

Figure 8: Parasites, veterinary problems and their frequency in horses as 

observed by farmers 52 

IX 



LIST OF TABLES 

Table 1: Description of individual condition scores of horses 30 

Table 2: Larval identification in feces of horses 36 

Table 3: Helminth species with their egg per gram (EPG) ranges recovered 

from 24 horses at Kestell 40 

Table 4: Comparison of horse ages from between two study areas in Kestell 

41 

Table 5: Physical conditions of horses from two study areas in Kestell 42 

Table 6: Packed cell volume (PCV) values of horses from two farms in 

Kestell 42 

X 



ABSTRACT 

A survey of helminthes occurring in horses at Kestell in the northeastern 

region of the Free State Province was conducted for a period of ten months 

(June 2002-March 2003). The aim was to determine the factors influencing 

helminth parasites infections and to record the ticks of veterinary importance 

in horses in the northeastern Free State. Blood, fecal samples and ticks were 

collected from 24 horses on the same farms every month for a period of ten 

months. The age of horses was between five months and seven years. 

Collection was done from both males and females. Fecal samples were 

collected from horses for identification of helminthes, blood was collected to 

perform packed cell volume and ticks were collected for identification and 

recordings. McMaster, coprological and Visser sieve techniques were used 

for egg counts. A total of three helminth species and a protozoan were 

recovered. Dominating species were strongyle; with egg per gram (EPG) 

values ranging between 0 and 4400. An R test showed that there was 

significant difference between age (p = 0.0218), seasonality (p< 0.0001) and 

physical conditions (p < 0.0001) in the prevalence of strongyle. This means 

that the younger horses had higher infestation levels; colder months had 

lower infestation rates and the better the physical condition of the horse the 

lower the infestation. It also showed that there is a strong linear relationship 

between packed cell volume (PCV) and (r = - 0.23465; p- value= 0.0004). 

Larval identification was done through preparation of fecal cultures. Small 

strongyle larvae made up more than 80% of larval cultures in all samples 

cultured. Blood samples were collected to conduct a PCV test. The readings 

were found to be normal ranging between 24 and 44. Rhipicephalus evertsi 

XI 



evertsi was were the only two tick species collected from the horses. A 

questionnaire survey was concurrently carried out to determine the influence 

of socio-economic factors on the management of horses, which may favour 

helminth infestation in these species. From the owners interviewed 35.8% 

were pensioners and unemployed. A total of 67% of horse owners utilize 

their horses everyday for transport, but the frequency range from once or 

twice a week. Only 39% of owners use herbal or natural product or drugs to 

treat their animals, whereas 23% use commercial products. Horses belonging 

to 90% of the owners were given lucem hay all year round, a few owners fed 

their horses on mealies and other utilized the veld to feed their horses. The 

disease conditions reported were worms, ticks, eye lesion, hoof problems, 

skin problem and infectious diseases. 45% of owners asked their friends or 

neighbours who had knowledge of horses for advice when their animals 

became sick and 30% treat the animals themselves. 19% reported that they 

did nothing and 6% took their animals to the state veterinarian. 

Approximately 3% made use of animal health inspectors, private 

veterinarians and traditional healers. Many owners (87%) allowed their 

horses to roam free during the day and about 84% of owners kept their 

horses in kraals or small camps during the night. 

The information gathered from this study provides the first documentation 

study on helminthes of veterinary importance in horses in the northeastern 

Free State. 

XII 



CHAPTERl 

INTRODUCTION AND LITERATURE REVIEW 

1.1 Helminth parasites of horses 

Equids are host to more than 75 species of helminths belonging to 28 

genera of nematodes, five species of trematodes and four species of 

cestodes (Krecek et al., 1994a and 1987; Lichtenfels, 1975). The poor 

nutrition and heavy work to which horses are subjected to, coupled with 

common grazing are ideal conditions for the proliferation of internal 

parasites. Almost all animals are infected with a range of parasites and a 

single parasitic infection is rare. Many parasites infecting equids also 

infect other species of livestock and cross-infection is common (Eysker 

and Pandey, 1989). 

Numerous studies on horses and ponies have reported that strongyle 

infections might result in alteration in the host's blood composition 

(Murphy and Love, 1997). These included changes in the oesinophil 

count; erythrocyte count and serum protein levels in horses and ponies 

that harbour large helminth burdens. All these effects appear to be 

ambiguous indicators of strongyle infection as it is difficult to determine 

with certainty which group (for example, the large or small strongyle) or 

which species are responsible for specific alteration in the blood 

chemistry (Matthee et al., 2000). 

1.1.1 Phylum Nematoda 

Nematodes are roundworms which make up large assemblage of 

relatively simple structured organism with a widespread distribution. 

Species which live in the intestine are generally larger, and those in the 



tissue attain relatively enormous length (Smyth, 1994 ). Adult worms 

living in the lumen of the intestine produce eggs that pass into the 

environment. There the eggs hatch and develop into infective larvae and 

horses ingest the larvae as they graze. Once inside the gastrointestinal 

tract of the horse, the larvae penetrate the large intestine and become 

encysted. It is this process that can cause disease (Williams, 1999). 

1.1.1.1 Examples of nematode species that infect horses 

In natural infections the strongylid burden comprises a mixture of several 

genera and species and they are conveniently divided into two subfamilies 

based on their morphological and migratory characteristics (Giles et al., 

1985). The so-called 'large strongyles' (subfamily Strongylinae) are 

characterized by lengthy migration of their larvae within the abdominal 

cavity, the long prepatent period and the attachment and 'plug feeding' of 

the adults on the caecal and colonic mucosae (Giles et al., 1985). 

The 'small strongyles' or the cyathostomes (subfamily Cyathostominae) 

comprise a group of over 40 species that are morphologically and 

biologically similar. These species have in fact been grouped into 

convenient practice for clinicians, often still under the all-embracing 

genus Trichonema. Cyathostome (trichoneme) larvae undergo only a local 

migration in the gut wall and have a shorter prepatent period (Round, 

1969), although this may be prolonged by hypobiosis (Ogbourne, 1978). 

The bulk of adult cyathostomes are only superficially attached to the 

colonic mucosa and do not ingest blood (Giles et al., 1985). 

The studies conducted in South Africa on helminths of different zebra 

species have contributed greatly to the knowledge and indicate that some 

2 



strongyle species are host specific and restricted to one host, whereas 

others are less specific (Krecek et al., 1987 and 1994b, Scialdo-Krecek, 

1983; Scialdo-Krecek et al., 1983). However, these studies also 

emphasize the need for extensive research regarding the abundance, 

prevalence, and site distribution of helminth parasites in equids and the 

influence that the external environment may have on both the worm 

species composition and abundance in this host (Matthee et al., 2000). 

Over the past years, there has been an increased interest in the role of 

small strongyles in disease production in horses. It was previously held 

that small strongyles were of low pathogenicity to horses; however, it is 

now accepted that these parasites often result in severe disease (Williams, 

1999). 

Over the past twenty years or so, the prevalence of cyathostome appears 

to have increased rapidly. In recent surveys the cyathostomes have 

accounted for up to 100% of pasture larval counts (Herd and Gabel 1990; 

Herd, 1986). Although a healthy horse may carry large numbers of small 

strongyles with no obvious deleterious effect on its health, infestations by 

these parasites, especially the larval stages, are being increasingly 

recognized as an important cause of disease (Mair, 1994 ). 

The amount of information available on small strongyle species of equids 

and the relationship between these hosts, the parasites and their 

environment is limited in Africa. Considering that there are 51 African 

countries and working equids inhabit most, this paucity of information 

reflects the limited knowledge currently available (Matthee et al., 2000). 

Cyathostomes, and the disease they cause as larval cyathostomosis, are a 

3 



group of parasites that inhabit the colon and cecum of horses. Up to 40 

different species of small strongyles have been identified and they 

represent the most common parasites of horses on pasture. 

The most widely recognized disease associated with cyathostome 

infection is diarrhoea. In two separate studies of diarrhoea in adults 

horses, cyathostome associated disease was the most common diagnosis 

(Love et al., 1992). The syndrome most commonly associated with 

infections by cyathostomes is caused by the mass emergence of 

previously inhabited fourth stage larvae through the ceacal and colonic 

mucosae, and is referred to as acute larval cyathostomiasis. This disease is 

characterized by an acute onset of diarrhoea that becomes chronic, 

accompanied by rapid weight loss, subcutaneous oedema and sometimes 

death (Reilly eta/., 1993; Giles et al., 1985; Mirck, 1977; Blackwell, 

1973). Horses are usually affected in late winter or early spring, and are 

mostly adults less than five years old. Typical pathological findings 

include neurophilia, hypoalbuminaemia, hyperbetaglobulinaemia and the 

presence of numerous fourth or early fifth stage larvae in the faeces. 

Larval cyathostomiasis has also been recorded as a cause of recurrent 

bouts of diarrhoea in aged ponies. Other clinical symptoms associated 

with cyathostome infection include colic and chronic weight loss 

(Ogbourne, 1978). 

Experimental infections have produced pyrexia, tachycardia, delayed 

shedding of winter coats and loose abnormal faeces (Tiunov, 1951 ). 

Infection is characterized by changes in serum protein chemistry in the 

fifth or sixth week post infection. The pathogenesis of cyathostome 

infections of horses has been reviewed by Ogboume, ( 1978). Research 

4 



activity on the small strongyles of horses is high because: (1) a disease 

syndrome in which larval stages emerging from the wall of intestine, 

colon and ceacum may cause severe colitis or death of horses in more 

frequently recognized (Mair, 1994; van Loon et al., 1995; Mansmann, 

1997); (2) resistance to anthelmintics has been reported widely (Herd and 

Coles, 1995; Ihler, 1995; Gawor, 1995) and (3) prospects for biological 

control appear to be promising using nematode- trapping fungi (Larsen et 

al., 1996; Bird and Herd, 1995). 

Parascaris equorum the roundworm is located in the small intestine of 

horses, is white in colour and up to 30cm long with three prominent lips. 

The principal source of infection for young foals is contamination of 

pasture paddock or stall with eggs from foals of the previous year. Adult 

worms in heavy infections can cause bile duct and intestinal obstructions 

and occasionally gut perforation. Damage is more pronounced in foals. 

Acute parascariasis is also accompanied by severe enteritis resulting in 

alternating constipation and foul smelling diarrhoea (Kaufmann, 1996). 

According to Soulsby (1982) and Kaufmann (1996) patent infection of 

Parascaris is occasionally found in mature horses, but they are of little 

clinical consequences. 

Parasitic worms of the family Strongylidae are ubiquitous in the grazing 

horse population and responsible for a wide range of clinical symtoms. In 

the competitive world of parasites, worms of the Strongyloides genus 

occupy a special niche where their survival is strictly connected with the 

presence of suitable hosts in the same ecosystem. These nematodes with 

unusual adaptation properties gave rise to relationships between two 

5 



ecosystems such as the external environment and mammalian organisms 

and became relatively independent from both ecosystems. These parasites 

need external maturation to settle into other individuals (Ziomko and 

Yvore, 1996). 

Members of the genus Strongylus are blood-sucking parasites of the colon 

and caecum of equines, and often referred to as palisade worms. The 

development and transmission of three species have been investigated in 

some detail (Reinemeyer, 1986). When the infective larvae are ingested 

with food of the host, the third and fourth stages undertake curious 

migration in the tissues before returning to the gut where they mature 

(Anderson, 1992). Strongylus species cause the greatest losses from 

helminths in horses and Strongylus vulgaris is the most important species. 

The prevalence of infection approaches 100% in foals, but the 

pathogenesis seen in any one host is directly related to the intensity of 

infection (Marqhuardt & Demaree, 1985). According to Reinemeyer 

(1986), small strongyle ova usually comprise over 95% of the strongylid 

ova in a horse fecal sample. Cyathostome larvae, however, if present in 

large numbers, can be much more important, both in their long term 

effects on body weight and in causing the sudden onset of diarrhea 

(Reinemeyer, 1986). 

Control of roundworms in horses presents some interesting problems 

because of peculiarities of pathogenesis in some species, different times 

of acquisition of other species, and interactions among populations of 

parasites. The organisms are cosmopolitan. Gastrointestinal helminths, 

mainly nematodes, are a major cause of disease in animals (Holmes, 

1987). They cause great loss to livestock and their control reqmres 

6 



frequent use of anthelmintics (Gray, 1987). In Africa the use of 

anthelmintics is generally limited by their relative high prices; in addition 

anthelmintic drugs are often diluted or stock under-dosed (Shillhom Van 

Veen, 1986). Such practices can lead to drug resistant strains of helminths 

and this is indeed becoming a widespread problem (Borgsteede et al., 

1991 ). 

1.1.2 Phylum Platyhelminthes 

1.1.2.1 Class Trematoda 

Trematodes occur in a wide range of host environments, the majority of 

the species are endoparasitic but some are ectoparasitic. The larval stages 

may occur in invertebrate ( especially molluscs) hosts and vertebrate hosts 

but the majority of adult stages occur in or on vertebrates. Specimens 

range in length from 1mm to 75mm and are usually grey or creamy white 

in colour, but many acquire a characteristic coloration due to the 

assimilation of food materials from the host. The mouth and reproductive 

apertures are typically anterior. The digestive system is well developed 

and food material consists of intestinal debris, blood, mucus or other 

tissue exudates depending on the host environment (Smyth, 1994 ). 

1.1.2.1.1 Example of trematode species that infect horses 

Fasciola hepatica remains one of the most important helminths of 

livestock in many countries of the world although it does not match the 

collective significance of nematodes. Its tropical counterpart is Fasciola 

gigantica. There are effective strategies for the control of fasciolasis, 

based largely on the drug fasciolicide (Fairweather and Boray, 1999). 

7 



The infection of livestock by Fascia/a species causes worldwide 

economic impact, estimated at over three billion US dollars per year. In 

many parts of the tropics fasciolosis is the most prevalent helminth 

infection, with rates of 30-90% in Africa and 25-90% in Indonesia 

(Mulcay & Dalton, 1998). Fasciolosis is associated with poor rate of 

weight gain in animals and the disease is caused by the migrating 

immature parasites eliciting hepatic tissue damage and inflammatory 

responses (El-Ghaysh et al., 1999). 

Fasciolosis is an important cosmopolitan disease of certain herbivorous, 

domestic and wild animals caused by the trematode F. hepatica. The 

mammalian host is infected by ingesting encysted metacercariae, which 

then invade and develop in the livers of their hosts to cause great losses 

(Ngategize et al., 1993). 

Gastrodiscus aegyptiacus is located in the colon and small intestine of 

equines. Heavy infections of this intestinal fluke are accompanied by 

diarrhoea, anaemia, oedema, emaciation and marked weakness. Adults 

have a relatively low level of pathogenicity. A high number of immature 

flukes can cause severe problems (Kaufmann, 1996). Previous infection 

and the age of the host afford some protection against reinfection, and 

acute disease is, therefore, usually seen only in young animals (Soulsby, 

1982). 

The long-term commercial outlook for the current chemical treatment 

programme, based on triclabendazole (Fasinex) appears weak because of 

a number of problems, such as environmental issues concerning residues 

arising from long-term veterinary drug treatment (El-Ghaysh et al., 1999). 

8 



1.1.2.2 Class Cestoda 

Cestodes belong to the group of parasites called tapeworms. Typically, 

they have scolex or "head" and a flattened strobila or "body". Various 

structural differences separate the species of tapeworms. One of the most 

obvious ones is the flaps or lappets found on the scolex. The scolex, 

equipped with four suckers, is used for attachment to the organ (usually 

intestine) that the tapeworm parasitizes. A strobila is composed of a 

ribbon of individual segments or proglottids. Each proglottid contains 

various body systems including reproductive organs. The most posterior 

proglottids become gravid or literally filled with eggs and then separate, 

passing out with feces (Lyons et al., 1997). 

Tapeworms have no mouthparts and cannot actively ingest food. 

Nutrients are absorbed through the body wall of the proglottids. The life 

cycle includes the definitive host (horse) in which they mature and 

intermediate host ( oribatid mite) in which immature stages are found. 

Horses, as they graze or eat other feed, accidentally ingest oribatid mites 

infected with immature or cysticercoid stages. Inside the horse 

cysticercoids develop to adult tapeworms after about two months. 

Tapeworm eggs within gravid proglottids, pass in horse feces and are 

eaten by free-living soil or oribatid mites. Within the mites, cysticercoid 

stages develop after two to four months. Horses then eat infected mites 

and the tapeworm cycle continues (Lyons et al., 1997). 

Diagnosis of infections of tapeworms in live horses is difficult. Detection 

of their eggs in horse feces is not reliable by standard techniques for 

determining presence of eggs of other internal parasites, such as 

nematodes. Therefore, not finding the tapeworm eggs in feces does not 

9 



mean that these parasites are actually absent in a horse. Tapeworm eggs 

are angular and vary in appearance, depending on the view presented. The 

eggs have hyaline-like thickened walls and contain an embryo with six 

booklets (hexacanth). Tapeworm infection can sometimes be verified by 

finding specimens in the feces after a horse has been treated with a drug 

activity against these parasites (Lyons et al., 1997). 

1.1.2.2.1 Examples of cestodes species that infect horses 

Anocephala species is located in the small intestine of horses and 

donkeys. It is the largest tapeworm of equines. It can become up to 8cm 

long and 2cm wide and has a typical tapeworm structure. High numbers 

of Anocephala magna can cause catarrhal or hemorrhagic enteritis 

(Kaufmann, 1996). 

Anocephala perfoliata is a cestode of the family Anoplocephalidae. It has 

an indirect life cycle via pasture dwelling orbatid mites. Grazing horses 

ingest mites containing infective cysticercoids of the parasites. The 

parasites attach by means of suckers situated on the scolex to the 

intestinal mucosa of the ileocaecal junction. It matures into an adult after 

6 to 10 weeks and attains a final size of only 5 to 8cm in length. Adult 

parasites shed gravid proglottids that break up during passage through the 

horse's large intestine, which can take in excess of 48 hours. Coprological 

diagnosis of A. perfoliata is highly specific, due to the eggs' characteristic 

appearance, but feces of infected horses contain small numbers of 

tapeworm eggs, resulting in poor sensitivity (Proudman and Trees, 1999). 

Although Anocephala perfoliata was previously regarded to be relatively 

harmless, infection of equines in recent reports have suggested its 



potential pathogenicity in the horses, because the parasite can cause 

significant gastrointestinal disease or even death (Proudman and Edwards, 

1993; Owen et al., 1989; Beroza, 1983 and Barclay et al., 1982). An 

increasing prevalence of the tapeworm has been attributed by some 

authors to changes in climatic factors that directly influence the 

propagation of the orbatid mite, intermediate host of the cestode (Geering 

and Johnson, 1990), and also to the widespread use of ivermectin in 

equine anthelmintic programmes (Edwards, 1986), promoting higher 

tapeworm burdens through lack of competition from other gastrointestinal 

parasites (Meana et al., 1998). 

Until recently, the equme tapeworm was difficult to diagnose and 

considered being of questionable pathogenicity. The equine tapeworm A. 

perfoliata was considered for many years to be an accidental finding in 

the intestinal tracts of horses at postmortem examination, and rarely 

associated with clinical disease. A number of studies have documented 

the prevalence of A. perfoliata in different countries throughout the world. 

More than 50% of thoroughbreds examined in central Kentucky, United 

States of America the last several years were infected with A. perfoliata. 

It does not appear to be an acquired or age resistance to this parasite in 

horses of all ages, including older ones, can be infected. Reported 

prevalence varies from 14% to 18% (Kaufmann, 1996). 

Detrimental effects are usually difficult to attribute directly to tapeworms. 

More implications of problems associated with A. perfoliata have been 

suggested than with the Anoplocephala magna and Paranoplocephala 

mammillana. The normal site of attachment of A. perfoliata is around the 

ileocecal valve. Large numbers may directly or indirectly cause reduction 

11 



of this opening. There may be ulceration, inflammation, and formation of 

a diphtheritic membrane where the parasites are attached. Various other 

pathologic effects reported are perforation, intussusception (prolapse) of 

the terminal ileum and cecum, and hypertrophy/ hyperplasia (thickening) 

of the ilea walls. These effects seem to be -more prevalent in weanling, 

yearling and adolescent thoroughbreds, which have been studied more 

than other breeds. Intussusception of the small intestine and cecum can be 

corrected surgically and prognosis is good if done promptly. Clinical 

signs for which A. perfoliata should be considered, as a possible cause are 

colic, poor growth, and unthriftiness. Anoplocephala magna have been 

associated with enteritis (Lyons et al., 1997). 

Treatment for tapeworms is a dilemma at this time because no drugs are 

labeled for their removal. However, pyrantel pamoate, on the market for 

removal of nematodes, has activity on A. perfoliata. This drug is 

commonly used because of its activity against A. perfoliata. At the 

therapeutic dose rate (6.6mg base/kg), it is somewhat less active than the 

double dose rate ( 13 .2mg base/kg). Even though a 20X margin of safety 

of the 6.6mg base/kg dose rate has been established, safety of higher dose 

rates has not been defined in breeding animals. Therefore, use of higher 

than the therapeutic dose rate of pyrantel pamoate is not recommended, 

particularly in pregnant animals. Limited data indicated at least some 

activity of the low dose rate (2.64mg/kg) of pyrantel tartrate on A. 

perfoliata (Lyons et al., 1997). 

Gongylonema pulchrum the gulletworm, is located in the mucosa of the 

oesophagus of horses, donkeys and ruminants. Gongylonema pulchrum 

lies embedded in the oesophageal mucosa in a zigzag fashion and reaches 

12 



145cm in length. Eggs are passed in the feces and hatch after being eaten 

by dung beetles in which the larvae develop to the infective stage. 

Infection of the horse occurs by eating the infected beetles. Gongylonema 

pulchrum is of little clinical importance (Kaufmann, 1996). 

1.2 Ticks as parasites of veterinary importance for horses 

Ticks are of considerable veterinary medical and economic importance as 

vectors of infectious disease of man and animals throughout the world, 

especially in Africa. Although different species of ticks and tick-bourne 

disease occur in various ecological regions, their impact on animal 

production is similar in nature and importance. They are responsible for 

severe losses either by tick worry, blood loss, damage to hides and udders 

and injection of toxins or through mortality or debility by the diseases 

transmitted (Hlatshwayo, 2000 ). 

1.2.1 Phylum Arthropoda 

Most ticks of importance from the veterinary point of view belong to the 

family Ixodidae. They have a hard dorsal shield or scutum covering the 

entire upper surface of the male and a relatively small scutum is just 

behind the head or capitulum of the female, nymph or larva. This scutum 

bears a patterns which is characteristics for each species of tick. 

Sometimes it is uniform in colour and the pattern is made up only of the 

pits, grooves and minute punctuations on it but in some ticks a colour 

pattern is also present. The rest of the body wall is leathery in appearance 

and extremely expandable, enabling the tick to take in a large volume of 

blood during each of the three periods in its life that it feeds. Its 

mouthparts, which are adapted for piercing and sucking, are visible from 

above in all stages. Two eyes are sometimes, but not always, present. 

13 



When present they are situated anteriodorsally, one on each side of the 

scutum (Hlatshwayo, 2000). 

1.2.1.1 Examples of tick species that infect horses 

The common name of Rhipicephalus evertsi evertsi) is the red-legged 

tick. The adults feed readily on cattle, horses, sheep and goats. They have 

also been recorded from many wild herbivores but only rarely from 

carnivores. The larvae and nymphae usually feed on the same host range 

as the adults and in addition, frequently infest wild hares. The most 

favorite site of attachment in adults is under the tail, and round the anus. 

Sometimes they attach on the groin. The larvae and nymphae usually 

attach deep down in the external ear canal, rarely elsewhere (Howell et 

al., 1978). 

The life cycle of R. evertsi evertsi depend on two hosts. The adults feed 

for about four to six days, sometimes longer, the female becoming bluish 

with a brownish tinge as she engorges. In summer she starts to lay eggs 

five days after dropping from the host and produces up to 7000 eggs, 

which hatch after approximately a month. During winter a month may 

lapse before she even begins laying and the eggs take up to two months to 

hatch. The larval-nymphal feeding period in the ear lasts about 10 to 14 

days and the nymphae subsequently take three to four weeks to develop 

into adults. Unfed larvae can withstand starvation for seven months and 

adults for over a year. Red-legged ticks are most active in summer and 

some specimens can be found all through the year (Howell et al., 1978). 

The red-legged tick is probably the most common vector in southern 

Africa of Babesia equi, causing biliary fever in horses and other equines. 

14 



At a certain stage it was also thought to be an important carrier of Babesia 

bigemina, causing redwater of cattle, but recent work has created doubt 

about this idea and its position is being reinvestigated (Howell et al., 

1978). 

Boophilus microplus is known as the blue tick and its adults are small, 

inconspicuous with a short mouth. The engorged females are bluish­

brown and can be seen attached to most of the body. The smaller females 

are brownish-yellow in colour. Boophilus microplus has a one-host life 

cycle, in which moulting from larva to nymph and nymph to adult takes 

place on the host. The time spent on the host, from the attachment of the 

unfed larva until the detachment of the engorged female, is approximately 

three weeks. Because of this short life cycle the tick is able to pass 

through several generations in one year. Boophilus microplus occurs 

throughout the year. In Australia and southern Africa, low winter 

temperatures synchronize egg development and hatching, so that the 

highest number of larvae is usually present on the pasture after the 

warmer weather of spring. 'Waves' of larvae then occur through the 

summer and into cool months of May and June (Coetzer and Erasmus, 

1994). 

1.3 Problems Facing Horse Owners 

Horses were domesticated for reasons fundamentally different from those 

of pigs, cattle, goats and sheep; these were primarily domesticated to 

create additional sources of protein. The horse family was not 

domesticated until other uses for animals had been discovered and 

accepted and, although equids were originally and in some cases still are 

used for food, they have mainly been draught and transport animals 

15 



throughout history. Horses appear to have been first domesticated in 

Eastern Europe, in the Ukraine, about 5500 years ago. The evidence for 

this is the large number of horse bones ( 60 % of all animal bones) at 

Ukraine sites. Equines provide work as saddle and pack animals, as 

pullers of carts, as draught animals for cultivation, as prime movers for 

lifting water from wells and for minor industrial purposes. Most equines 

are used in the immediate locality but some are used for long distance 

transport (Clutton-Brock, 1978). 

Most farmers face the problem of internal parasites and ectoparasites 

because they have little knowledge about them. There is very little 

knowledge about the management system under which the horses are kept 

in South Africa or about the impact of the helminth infections on the 

horses (Svendsen, 1997). 

1.3.1 Control of helminth parasites 

Control of internal parasites of equids has had a variety of classes of 

antiparasitic compounds for approximately the last 60 years (Lyons et al., 

1999). First to appear on the market were diphenylamides (phenothiazine) 

in the 1940s, followed by piperazines in the 1950s and benzimidazole 

(e.g. Thiabendazole), organophosphates (trichloroform and dichlorvos), 

imidothiazole (levamisole) and pyrimidines ( e.g. pyrental tartrate and 

pyrental parmoate) in 1960s and 1970s. The first macrocyclic lactane 

marketed was ivermectine in 1983 and the second was moxidectine in the 

1990s. These latter compounds are active on parasitic arthropods and 

nematodes and are commonly called endectocides. Prevalence data on 

endoparasites from equine population, particularly data that might reflect 

16 



the impact of chemotherapy on parasite population, are difficult to obtain 

(Lyons et al., 2000). 

1.3.2 Managing ecto-parasites (ticks) on horses 

Ticks are bloodsucking organisms that attach to human or animal hosts at 

specific times during their cycle to obtain a blood meal. When full they 

drop off and remain hidden in thatch and overgrowth until it is time to 

feed again. Ticks are most commonly found in overgrown, brushy areas, 

which provide the shelter and humid conditions that ticks need. These 

areas also harbor the small mice and the other mammals that are 

important intermediate hosts during tick development. Avoidance of 

"ticky" areas, use of protectants and keeping horses in mowed pastures 

where the vegetation dries out quickly and allows penetration of sunlight 

will reduce problems with ticks (Townsend, 1998). 

1.3.3 Management of horses 

As most horses are not kept for meat and milk production but as transport 

animals they do in fact, require less in the way of management than if 

their functions were more complex. Some supplementary feeding may be 

provided and it veterinary services are available these are often in urban 

centers where equines are gathered for transport purposes, here may 

receive considerable medical care. Equines indeed usually figure as the 

largest group of animals treated at veterinary centers (Townsend, 1998). 

1.3.3.1 Management systems 

The total number of horses in Africa is estimated to be 500 000, compared 

to 50 million worldwide. Most horses in Africa are used for recreation 

17 



rather than work. South Africa has 280 000 horses, chiefly pure-bred 

(Anon, 1997). 

In Africa, working domestic equids are most often used in rural and 

resource-limited communities. These communities embrace a wide range 

of farming and management system in which the control of disease agent, 

such as cyathostomes, has not yet been well tested. For example, for many 

of these owners the use of anthelmintics is constrained by both the cost 

and their availability. The agricultural co-operatives or other sources 

where such products are available are often long distances away and 

therefore inaccessible. Such a situation calls for alternative strategies for 

nematode control, which are cost effective, appropriate and acceptable to 

owners. In Africa, there is only one available report anthelmintic 

resistance in horses and that is in South Africa (Krecek, R.C. and Guthrie, 

A.J, 1999). 

1.3.3.2 Alternative approaches to control 

Because of financial constraints of owners, lack of availability of 

anthelmintics and the occurrence of anthelmintic resistance, alternative 

methods of controlling helminth parasites of equids are needed. The 

alternative strategies are fecal removal, biological control including 

nematode-trapping fungi and selective chemotherapy (Krecek, R.C. and 

Guthrie, A.J, 1999). 

a. Fecal removal 

A human activity, namely the mechanical control practice of fecal 

removal or collecting dung to use as fuel, building material and for 

composing, acts to interrupt the life cycle of parasites. The pasture 

18 



hygiene approach was designed for horses kept under intensive conditions 

in USA and UK where constant re-infection problems occurred (Herd, 

1993). Twice weekly removal of excessive feces provided superior 

cyathostome and ascarid control as well as well as a 100 % increase in 

grazing area, and freedom from dung-related problems. The cost of 

pasture sweeping or vacuuming may thus be offset by improved worm 

and colic control, slower selection for anthelmintic resistance, and by the 

increase grazing area due to the elimination of ungrazed roughs around 

fecal deposits. This approach was of particular value in controlling the 

unique problems of weanling and yearling horses under intensive grazing 

conditions (Herd and Gabel, 1990; Herd, 1986). 

b. Nematode-trapping fungi 

Biological control implies situations when man attempts to use naturally 

occurring antagonists to lower a pest population which would otherwise 

causes losses of plant and animal production (Gronvold et al., 1996). In 

practice, biological control has no direct application to internal animal 

parasites, when in their parasitic stage. However, the parasitic stages may 

be indirectly regulated by biological control of the free-living larval 

stages on pasture (Gronvold et al., 1996). 

Numerous examples of organisms, which exploit free-living stages of 

parasites as a source of food, are found in nature. Such examples are 

important to study in that they may prove to be a potential form of 

biological control (Gronvold et al., 1996). Sayre and Starr (1988) list 

some biological control agents of helminths as invertebrates, dung bettles, 

earthworms, microarthropds (such as macrochelid mites), microorganism, 

bacteria and fungi. The most prom1smg is fungi, which exhibit 

19 



antinematodes properties. Fungi with these properties have been 

recognized for some time and consist of a variety of species. The most 

important group of nematophagous fungi includes nematode-trapping 

(predacious) fungi and endoparasitic fungi. Other fungi antematode 

properties either invade nematode egg or produce metabolites toxic to 

nematodes (Barron, 1977). 

Persmark ( 1997) discusses predacious and endoparasitic fungi and stated 

that they are found in all environments throughout the world, but are 

particularly abundant in rich agricultural soils. Under laboratory 

conditions, where these fungi are grown as a monoculture on 

standardized, nutrient-poor media and are provided with a nematode prey 

that cannot escape, results can be very successful with nematode larvae 

captured and destroyed within a matter of hours. However this type of 

work provides little relevant information, as how these fungi would 

perform as practical biological control agents against parasitic nematodes 

larvae under field conditions. The parasite control efficacy of each fungus 

should be considered and evaluated within the livestock production 

systems being considered (Krecek, R.C. and Guthrie, A.J, 1999). 

One proposed application is to incorporate nematophagous fungi into feed 

blocks. These blocks could provide a means of low-cost nutrient 

supplementation, can be manufactured using simple technology, and those 

manufactured in the developing world often-incorporate surplus plant by­

products as the nutrient source. Such fungal blocks could prove to be a 

particularly important control option in the tropic and subtropics where 

anthelmintics are not widely available, the value of animal (horses) is less 

20 



than the value of the treatment, an the shelf life of the feed blocks is six 

months or more (Waller, 1997). 

c. Selective chemotherapy 

Selective chemotherapy refers to the judicious use of anthelmintics by 

applying criteria in deciding to give a dose of remedy. A comparison 

between the effects of conventional and selective antiparasitic treatments 

on nematode parasites of horses from two management systems in South 

Africa (Krecek et al., 1994a) revealed that selective treatment resulted in 

considerable saving and advantage of the avoidance of further 

anthelmintic resistance development. Duncan and Love ( 1991) were the 

first to report on this alternative strategy of controlling strongyles in 

horses in the UK. The large size of the horse ( such as 400 kg) and the 

relative high cost of the anthelmintic encourage this approach among 

horse owners (Krecek, R.C. and Guthrie, A.J, 1999). 

1.4 Socio-economic factors 

A socio-economic aspect of animal disease in southern Africa is a topic 

under review in South Africa (Krecek et al., 1995). Changes, which are 

taking place in the country, demand a revised approach to meet broad 

national development requirements in terms of socio-economics (Krecek 

et al., 1995). 

According to Krecek et al ( 1995) socio-economic factors have a strong 

influence on the distribution, dynamics and significance of animal 

diseases, particularly in developing countries where there are wide 

differences in the socio-economic status of their inhabitants. Socio­

economic factors operate at different levels of resolution, between which 

21 



their importance often varies; the most important of these resolutions are 

households, community and nation. 

In order to examine the socio-economic consequences of animal diseases, 

it is necessary to briefly examine the definitions and the context of this 

area of investigation. The prefix socio- refers to whole societies or to 

individuals. Sociology includes the customs, traditions and patterns of 

historical development and institution that have evolved within societies. 

These include the type of government or legal system, regulations of 

property ownership, education arrangements, veterinary or medical 

arrangements and family structures. Sociology looks at the nature and 

behavior of social groups and how are they similar and how they differ 

from each other. Branches of Sociology examine diverse groups within a 

society. Socio-economic status usually relates to levels of education, 

income or occupation (Krecek et al., 1995). 

Socio-economic factors are generally taken to mean the non-physical 

properties or characteristics of human environments, which can greatly 

influence the natural environments. In broad terms we refer to the 

economic status of human populations and all the other characteristics 

which can be influenced by that, such as level of education, access to 

resources, including capital, land and services. In addition to the 

economic status anthropological characteristics may also influence 

attitudes to education, attitudes toward technology adaptations, attitudes 

towards land tenure and many of these characteristics enhance or diminish 

the effect of economic factors exerting their greatest influence in the more 

impoverished communities (Krecek et al., 1995). 

22 



Krecek et al ( 1995) micro-epidemiology provides the socio-economic and 

socio-cultural factors that affect the distribution and importance of 

parasitic diseases and their method of control where health education and 

community involvement are essential features of the programme. The 

occurrence and prevalence of parasitic infections in a given locality are 

reflections of a complex interaction between the environment and the host 

species that are present. The ability to monitor the impact of diseases 

depends upon setting up facilities that are available. Throughout the world 

this varies from one extreme, the extensive grazing practices of nomadic 

or transhumanant people, to intensive and non-intensive systems in 

developed areas. 

23 



CHAPTER2 

OBJECTIVES 

2.1 Rationale 

Helminth infections are of considerable economic importance in livestock 

production. These infections not only cause clinical disease and 

mortalities but also cause production losses such as reduced weight gain. 

They also cause economic losses through condemnation of the whole 

carcass or specific organs at slaughter. The economic loss due to parasitic 

infections in South Africa is very high, and this is because of the wide 

range of parasites in the country. There is very little knowledge about the 

management system under which they are kept in South Africa or about 

the impact of the helminth infections on the horses (Svendsen, 1997). 

Several factors such as limited resource, unavailability of relevant 

information and veterinary services and the misconceptions that helminths 

are not important because they can not be seen in animal, compared to 

ectoparasites such as ticks (Wells et al., 1998b, Starkey, 1995) all 

contribute to an apparent lack of internal parasite awareness and 

consequently their control in horses. Most of what is known about the 

effect of helminth species on equids (Murphy and Love, 1997) and the 

value of alternative control methods (Waller, 1999) is based on studies on 

horses in developed countries. 

This study investigates the current prevalence and socio-economic factors 

influencing the helminth infections of horses at Kestell in the north 

eastern region of the Free State Province South Africa. This information 

will help the government planners and researchers and will shed light on 

the most important helminth parasites encountered around Kestell. The 
24 



availability of such information will be crucial in understanding disease 

patterns and for effective control and disease management programmes. 

Using known and established methods like the McMaster, Visser sieve 

and Centrifugation techniques it was possible to determine the various 

helminth species of horses in this region. The major objective of this 

study was to determine helminth parasites of veterinary importance in 

horses. Data collected will form the basis in the development of 

appropriate control strategies against internal helminths of economic 

importance in horses at Kestell in the north eastern region of the Free 

State Province. 

2.2. General objectives 

To determine factors influencing helminth infection and to record ticks of 

veterinary importance in horses at Kestell in the north eastern region of 

the Free State Province. 

2.3 Specific objectives 

❖ To determine the prevalence of helminths in horses at Kestell 

in the north eastern Free State Province. 

❖ To record ticks of veterinary importance in horses at Kestell 

in the north eastern Free State Province. 

❖ To determine the socio-economic factors influencing 

helminth management in horses ( Questionnaire survey). 

25 



CHAPTER3 

MATERIALS AND METHODS 

3.1 Description of the study area 

The study was carried out between June 2002 and March 2003 in the 

north eastern Free State Province at Kestell (28°38' E; 28°20' S), which is 

located+/- 50 km, 28 km respectively, from the Qwa-Qwa Campus of the 

University of the Free State (Figure 1 ). The north eastern Free State is a 

predominantly hilly and mountainous area situated between latitudes 28 ° 

and 30° S, and 28° and 30° E. Geology of the north eastern Free State 

Province with its beautiful landscape consist of rocks of the Karoo super­

group, namely, the Beaufort and Storm berg groups, with the soil types 

belonging to the Clovelly-Avalon, Katspruit, Kroonstad-Katspruit and 

Sterkspruit groups. Numerous dolerite dykes and occasional sills have 

intruded the Karoo formations and a few small dolerite diatremas have 

also been recorded in Qwa-Qwa, which contain sedimentary breccias 

(Kritzinger and Pieterse, 1987). 

The north eastern Free State lies within the summer rainfall region of 

South Africa with more than 85 percent of the precipitation occurring 

during the period September to March, mainly in the form of 

thunderstorms. The temperature in the eastern Free State may be 

described as being cool to moderate warm. The average temperature 

during mid winter is 7.4°C and during mid-summer 17.9°C. The average 

daily minimum temperature during winter is 4.6°C and the average daily 

maximum temperature during summer is 29.9°C. Cold spells, i.e. 

temperatures less than 5°C occur fairly often throughout the year and 

usually, last several days at a time. Hot spells, i.e. temperatures in excess 

26 



• STAICl[RTOH 

TRANSVAAL 

• ICROOIICSTAO 

IL.OEMS"'V&T 

LESOTHO 

CC•CTSO-=-' . ... 
Figure 1: Map showing the location of the study site, Kestell in the north 

eastern Free State Province of South Africa. 

27 



of 35°C also occur for several days per year. During September and 

October temperatures are highly variable, while during April and May it 

is fairly stable (Kritzinger and Pieterse, 1987). 

The north eastern Free State belongs to the grassland biome, and includes 

five vegetation types, namely, moist cool highveld, moist cold highveld, 

afro-montane and alti-montane grassveld (Moffett, 1997). 

3.2 Collection of blood ticks and fecal samples 

Blood, ticks and fecal samples were collected from horses (Plate 1) over a 

period of ten months (June 2002 to March 2003). The experimental 

animal physical conditions were assessed using body condition score 

method (Figure 2) by Henneke et al ( 1983 ). The system is based on the 

nine points scale with a score of one representing poor and mne 

representing extremely fat (Table 1 ). A total of at least 24 horses 

were sampled every month at Kestell. Fecal samples were collected 

directly from the recta of the animals (Plate 2) and used for worm egg 

counts (EPG) and third stage larvae identification. Fecal egg counts was 

done according to McMaster (Reinecke, 1983), Visser sieve (Malan and 

Visser, 1983) and centrifugation/floatation (Beroza et al., 1986) 

techniques. Larval identifications were done through the preparation of 

fecal cultures (Michael, 1999). 

3.3 Fecal worm egg counts 

It is important to understand that demonstration of parasite eggs or larvae 

in the feces provides evidence that animals are infected but often does not 

accurately indicate the degree of infection. Fecal samples were collected 

28 



Crease down back Along the neck 
Along the . 
withers 

Tailhead 

I 
Ribs 

Figure 2: Diagram of areas palpated to estimate body fat and condition 

score. 

29 



Table 1: Description of individual condition scores of horses (Henneke 

et al., 1983) 

Score 

1 Poor 

2 Very Thin 

3 Thin 

Description 

Animal extremely emaciated. Spinous processes, ribs, 

tailhead, tuber coxae and ischii projecting prominently. 

Bone structure of withers, shoulders and neck easily 

noticeable. No fatty tissue can be felt. 

Animal emaciated. Slight fat covering over base of spinous 

processes, transverse processes of lumber vertebrae feel 

rounded. Spinous processes, ribs, tailhead, tuber coxae and 

ischii prominent. Withers, shoulders and neck structures 

faintly discemable. 

Fat build up about halfway on spmous processes, 

transverse processes cannot be felt. Slight fat cover over 

ribs. Spinous processes and ribs easily discernable. 

Tailhead prominent, but individual vertebrae cannot be 

visual identified. Tuber coxae appear rounded, but easily 

discernable. Tuber ischii not distinguishable. Withers, 

shoulders and neck accentuated. 

4 Moderately Negative crease along back. Faint outline of ribs 

thin discernable. Tailhead prominence depends on 

conformation, fat can be felt around it. Tuber coxae not 

discernable. Withers, shoulders and neck not obviously 

thin. 

5 Moderate Back level. Ribs cannot be visually distinguished but can 

be easily felt. Fat around tailhead begging to feel spongy. 

Withers appear round over spinous processes. Shoulders 

and neck blend smoothly into body. 

6 Moderately May have slight crease down back. Fat over ribs feels 

fleshy spongy. Fat around tailhead feels soft. Fat begging to be 

deposited along the side of the withers, behind the 

shoulders and along the sides of the neck. 

30 



7 Fleshy 

8 Fat 

9 Extremely fat 

May have crease down back .. Individual ribs can be felt, 

but noticeable filling between ribs with fat. Fat around 

tailhead is soft. Fat deposited along withers, behind 

shoulders and along the neck. 

Crease down back. Difficult to feel ribs. Fat around 

tailhead very soft. Area along withers filled with fat. Area 

behind shoulder filled with fat. Noticeable thickening of 

neck. Fat deposited along inner thighs. 

Obvious crease down back. Patchy fat appearing over ribs. 

Bulging fat around tailhead, along withers, behind 

shoulders and along neck. Fat along inner thighs may rub 

together. Flank filled with fat. 

31 



directly from the recta of the animals and placed in labelled containers 

(pill bags). Fecal worm egg counts were done using the McMaster, 

centrifugation/ flotation and Visser sieve techniques. 

3.3.1 Mcmaster technique (Reinecke, 1983) 

The procedure for performing this technique is summarized below: 

(i) Fecal samples were collected directly from the recta of the animals 

and placed in separate labelled containers (pill bags). 

(ii) 4g of fecal sample were weighed out on a weighing balance 

(Sartorius, South Africa). 

(iii) 56ml of a 40% sugar solution was added to horse feces as a 

floatation medium. 

(iv) The above mixture was then be blended with the aid of a 

commercial laboratory blender (Waring, South Africa). 

(v) To break the foam that was formed from blending, a few drops of 

amyl alcohol was added. 

(vi) The required number of chambers of a McMaster slide were then 

filled with the fecal mixture using pasteur pipettes (Elkay, South 

Africa). 

(vii) Slides were allowed to stand for approximately 2 minutes so that 

the eggs could float to the surface of the floatation medium. 

(vii) With the aid of light microscope (Nikon, Japan), the eggs were 

counted in the grid of each counting chamber at x400 magnification 

( eyepiece, x 1 0; objective, x 40) 

32 



3.3.2 Visser sieve techniques (Malan and Visser, 1983) 

The procedure for performing this technique is summarized below: 

(i) Fecal samples were collected directly from the recta of the animals 

and placed in individual labelled containers (pill bags). 

(ii) 4g of fecal sample were weighed out on a weighing balance 

(Sartorius, South Africa). 

(iii) A three-in-one filter (25 mm, 70 mm and 110 mm) was suspended 

in a filter stand over a large basin. 

(iv) The fecal material was placed in the inner (110 mm) filter. A course 

spray of water at high pressure was directed at the feces, moving 

the fecal material from the inner ( 110 mm) filter to break up and 

wash the feces through the other 75 mm and 25 mm filters. 

(v) Each filter retained coarser particles according to size, allowing the 

finer materials to pass through. 

(vi) The inner filter (110 mm) was removed and hanged in the ring 

provided on the stand and washed again. 

(vii) Water supply was shut off and the contents of the middle and the 

outer filters were drained into glass jars labelled 70 mm and 25 mm 

respectively 

(viii) Each filter was gently rinsed with a small volume of water ensuring 

that the volume in the glass jars did not exceed 60 ml. 

(ix) Four teaspoons of sugar was added to the jar labeled 25 mm. 

(x) The contents in the bottle marked 25 mm was stirred to dissolve the 

sugar. 

(xi) Using a pipette, all three chambers of a McMaster slide were filled 

with aliquots from the washings of the 25 mm sieve. 

(xii) The modified McMaster slide was filled with the aliquots from the 

70 mm sieve. 

33 



(xiii) The slides were then allowed to stand for a few minutes at room 

temperature. 

(xiv) The slides were examined using a standard light microscope at x 

400 magnifications ( eyepiece, x 1 O; objective, x 40). 

3.3.3 A centrifugation/ flotation (Beroza et al., 1986 ) 

The procedure for preparing a centrifugation/ flotation technique 

(i) Fecal sample were collected directly from the recta of the animals 

and placed in a separate labeled containers (pill bags). 

(ii) Approximately 40 g of feces were placed in a beaker. 

(iii) Mixed vigorously with 5 to 10 ml of tap water to a pasty 

consistency. 

(iv) The resulting mixture was then strained through a coarse sieve and 

the liquid collected in two 10 ml centrifuge tubes. 

(v) Both tubes were then spun at 1200 g for 10 minutes, the 

supernatant from both tubes was discarded and the fecal plugs were 

resuspended in tap water. 

(vi) Both tubes were spun again for 10 minutes at 1200 g and the 

supernatant from tubes was discarded. 

(vii) The fecal plugs were resuspened in separated sucrose (prepared by 

dissolving 450 g granulated sugar in 350 ml warm water and spun 

at 1200 g for 10 minutes. 

(viii) On the removal from the centrifuge the tubes were filled to the brim 

with saturated sucrose solution and a coverslip applied to the top 

(ix) After the tubes were allowed to stand for two hours, the coverslips, 

with any attached tapeworm eggs were placed on a microscope 

slide. 

34 



(x) The slides were then examined using a standard light microscope at 

x 400 magnifications ( eyepiece, x 1 0; objective, x 40). 

3.4 Fecal cultures from horses (Michael, 1999). 

The procedure for preparing fecal cultures is summarized below: 

(i) A 2 cm thick wooden stick was placed in the center of a fruit jar. 

(ii) A mixture of feces and vermiculite at an approximate volume ratio 

of 1: 1.5 was added into the jar. 

(iii) The mixture was pressed down with a second stick until the layer of 

feces is 7 cm thick. 

(iv) The inside of the jar and the compacted fecal mixture was 

moistened with water without soaking the contents. 

(v) The lid on the culture bottle was then lightly screwed on. 

(iv) Cultures were incubated in a moist incubator (Labotec, South 

Africa) at 27° C for 8 days. 

(vii) Larvae migrating on the surface of the culture bottles were 

harvested by moistening the inner walls of the culture bottles and 

collecting them in a clean beaker. 

(viii) The cultures were harvested from the upper surface of the bottle 

containing feces/ vermiculite mixture. 

3.4.1. Preparation of larvae for identification (Michael, 1999). 

(i) A small aliquot of larvae harvested from fecal culture was transferred 

into a microscope slide using a Pasteur pipette, a drop of iodine 

added and covered 

(ii) The larvae were identified using larval identification key (Table 2) 

35 



Table 2: Larval identification in feces of horses 

a. Length: 290- 850µm 

b. Body/ tail ration: 1.5/1 

C. Intestinal cells: 0-8 triangular 

d. Has sheath 

e. Tail long and whip-shaped Small strongyle 

f. Thicked: 14-18µm 

g. Well developed, clearly 

visible oesophagus 

• Length: 800-1 000µm 

• Body/tail: 2/1 

• Intestinal cells: 16-32 Large strongyle 

• No sheath 

36 



3.5 Blood sample collection and PCV determination (Michael, 1999). 

(i) Experimental animals were restrained and pressure was applied by 

means of a rubber band, which was held securely around the 

animal's neck to make the jugular vein bulge to facilitate 

introduction of the needle. 

(ii) An 18G 1.5 needle (Precision Glide, Europe) was used to collect 

blood in sterile ethylenediamine tetra-acetic (EDTA)-coated 

vacutainer tubes (Becton Dickinson Vacutainer System, United 

Kingdom). 

(iii) When sufficient blood is collected the vacutainers were gently tilted 

back and forth for a few minutes to allow mixing with the 

anticoagulant. 

(iv) In the laboratory, two capillary tubes (micro hematocrit tubes, 

Wertheim) were filled with blood samples and sealed on one end 

with clay. 

(v) Blood-filled hematocrit tubes were centrifuged in a micro hematocrit 

centrifuge (Taiwan) for 10 minutes to separate the plasma from the 

red blood cells. 

(vi) The packed cell volume (PCV), which is a measure of the percentage 

of red blood cells, was then measured using a micro hematocrit 

reader (Taiwan) (Michael, 1999). 

3.6 Questionnaire survey 

The study was conducted in Qwaqwa and Kestell in the north eastern Free 

State Province South Africa. The survey questionnaire was divided into 

five sections dealing with (demography) employment status of the farmers, 

(health) horse diseases, (nutrition) horse feeds, (breeding) horses 

37 



multiplication and (management) where animals are kept. These sections 

involve multiple-choice answers. 

A total of 31 questionnaire were distributed to the farmers. Different 

villages (Thibella, Phomolong, Moeding, Matswakeng and Malekunutu) in 

Qwaqwa were visited. The aim of distributing the questionnaires was to 

determine the socio-economic factors influencing the helminth 

management in horses. The farmers were questioned verbally and the 

answers were recorded on the questionnaire forms (Appendix 1 ). 

3. 7 Data presentation and analysis 

The data was analyzed statistically using the appropriate analysis of 

variance techniques. All statistical data was done on the software Program 

Statistical Analysis System (SAS). The R-square test distribution was used 

in testing the hypothesis of independence between different variables of 

classification. 

38 



CHAPTER4 

RESULTS 

4.1 Helminth distribution, diversity and abundance in horses 

Between June 2002 and March 2003 a total of three helminth species and 

one protozoan species were recovered from 24 horses at Kestell in the 

north eastern Free State (Table 3). The main species recovered was 

strongyle with egg per gram (EPG) ranging between 0 and 4400. Horses 

of ages ranging from 5 months to 7 years of both sexes were sampled 

(Table 4). Their physical conditions are presented in Table 5. 

Identification of helminth species was done by examination of only eggs 

and third stage larvae, and their classification was done to the genus level. 

The results of the larval identifications correlated with those of the egg 

count and identification. Blood was collected for packed cell volume 

(PCV), which determines anemia. The normal values range between 24 

and 44 for domestic horses and the results were found to range between 

24 and 44 (Table 6). 

The effect of age, sex and physical conditions was investigated. Based on 

5% significance level all except sex had significant effect on strongyle. 

The R test showed that there is significant difference between age 

(p=0.0218), months (P<0,0001) and physical conditions (p<0,0001) in the 

prevalence of strongyle. This means the younger the horse had higher 

infestation levels colder the months had a low infestation and the better 

the physical condition of the horse the lower the infestation. It also 

showed that there is a strong negative linear relationship between packed 

cell volume (PCV) and strongyle (r = - 0.23465; p- value= 0, 0004). 

39 



Table 3: Helminth species with their egg per gram (EPG) ranges 

recovered from 24 horses at Kestell 

Helminth species EPG values ranges 

Farm 1 Farm2 

Strongyle 0-4400 50- 3450 

Parascaris eqourum 0- 1350 0 

Oxyuris equi 0- 1750 0 

Eimeria spp 0- 100 0 

Total number of horses sampled per 12 12 

month for a period of 10 months 

40 



Table 4: Comparison of horse ages between two study areas in Kestell 

AGE OF HORSES PERCENTAGES 

Farm 1 Farm2 

5 months 17% -

7 months 8% 17% 

8 months 8% -

9 months 17% -

1 year 17% -

2 years - 17 % 

3 years 8% 33 % 

4 years 8% 8% 

5 years 8% 8% 

7 years - 8% 

Keys 
-: horses of this age were not found on the farm 

41 



Table 5: Physical conditions of horses from two study areas in Kestell 

Physical Condition PERCENTAGES 

Scores Farm 1 Farm2 

2 (Very thin) 25% 8% 

3 (Thin) 50% 42% 

4 (Moderately thin) 16% 50% 

Total number of horses 12 12 

sampled per month for a 

period of 10 months 

Table 6: Packed cell volume (PCV) values of horses from two farms in 

Kestell. 

Farm 1 Farm2 

Months and year 
PCV PCV 

June 2002 24 28 

July 2002 32 25 

August 2002 33 32 

September 2002 32 28 

October 2002 33 29 

November 2002 32 29 

December 2002 31 30 

January 2003 30 26 

February 2003 44 28 

March 2003 28 32 

Total number of horses 12 12 

sampled per month for 10 

months 

42 

-



4.2 Seasonal dynamics of helminth species isolated from horses 

The average EPG's of strongyle in both the farms (Figure 3 and Figure 4) 

showed the same seasonal pattern. At both the farms strongyle has 

reached a peak in summer month (January) and low EPG's were recorded 

during colder months (July). However, other helminths like Parascaris 

equorum, Oxyuris equi and protozoan Eimeria were stable throughout the 

year (Figure 3). Parascaris equorum, Oxyuris equi and Eimeria were only 

isolated from Farm 1. 

4.2 Larval cultures 

Small strongyle larvae made up more than 80 % of the larval culture in all 

samples cultured. On both the farms higher small strongyle percentages 

were found. The larvae were only identified as large or small strongyle. 

4.4 Seasonal dynamics of ticks isolated from horses in Kestell 

Ticks were also collected from 24 horses for a period of ten months. A 

total of 824 ticks were collected from Farm 1 and 1061 ticks were 

collected from Farm 2 over a period of ten months. Rhipichephalus 

evertsi evertsi was identified from horses. The infestation rate of horses 

with ticks ranged from at least five ticks on one horse to more than 

hundred ticks. The dominating species was found to be Rhipichephalus. 

Ticks of the species Rhipichephalus were located mainly in the ears and 

anal region. During infestations high level of intensity they were also be 

found in the perinea! region, on the fore head, and in the mane. The 

seasonal distribution for Rhipicehalus in Farml and Farm 2 are shown in 

Figure 5 and Figure 6 respectively. 

43 



Cl) 
(1) 
::J 

3400 

2800 

~ 2200 -C/J 

~ 
(1) 
ca 
; 1600 

E 
~ 
0) 
I-

~ 1(XX) 
0) 
0) 
(1) -
~ 400 
w 

• a A 1 A 
-200 ,._____.__.....,___......____.__.....,___..____.__.....,___..____.__....J 

Jlft .luty ~ Sep Oct Nov Dec Jan Feb March 

Figure 3: EPG vakJes of helminthic species of horses il Kestell (Fann 1) 

44 

-0-~ 

-+- Parascaris 

.....--()xyl.ris 

-6- Eimeria 



1600 
(/) 
(l) 
::J 
ro 
> -en 
(l) 1200 (.) 
(l) 
ro -0 
E 
ro 

800 ~ 

C> 
~ 

(l) 
a. 
0) 
C> 
(l) -C) 400 
a.. 
w 

0-------..._ ______ ..._ ___ _____ 
Jllle Jljy ~ Sept Oct Nov Dec Jan Feb March +- Strongyle 

Figure 4: EPG values of helminlhc spaces of torses i'I Kesten (Farm 2) 

45 



318 

265 

C 212 
G> 
"E 
::, 
.c 

t 159 
:.::; 

C 
Cl'J 
G> 
~ 

106 

53 

June July Aug Seit Oct Nov Dec - Jan Feb Marc 

D Male 

Female 

Figure 5: Mean monthly male and female Rhipicephalus burdens on horses on Fann l 

46 



fl) 
C 
Q) 

"E 
::, 
.0 
:y:, 
0 
:.:: 
C 
CV 
Q) 

:E 

400 

350 -

300 

250 
..... 

...... 

200 - .--
..... 

150 

100 ..... 
-

50 - -
0 l""'"1 :-, n ;I n ~ n -

June Jtiy Aug Sept OCt Nov Dec Jal Feb March 

Figure 6: Mean monthly male and female Rhipicepholus burdens on horses on Farm 2 

47 

Male 

Female 



4.5 Questionnaire survey 

Semi-structured interviews, based on discussions with relevant people in 

the community and a resultant problem conceptualization, were 

undertaken at 31 households in 11 villages of the north eastern region of 

the Free State Province. 

Little is known regarding the keeping of animals in the north eastern Free 

State, South Africa. Therefore the attitudes of horse owners to control 

helminth parasites, and the extent to which veterinary practitioners are 

involved in providing advice on parasite control of horses was researched. 

The replies to our questionnaire indicated that there is low level of 

awareness on the need for helminth control. 

Between February 2001 and November 2002 31 participants were 

interviewed; 96.8% of the owners were male and 3.2% were female. Their 

home language was Southern Sotho. 

Besides the horses other domesticated animals included donkeys (0.3%), 

mules (0.6%), cattle (16.7%), dogs (2.2%), goats (6.6%), sheep (8.6%), 

chickens (8.5% ), ducks (0.9%) and geese (0.2%) (Figure 7). 

4.5.1 Demography 

Of 31 owners interviewed, 35.8% were pensioners and unemployed; 30% 

were employed and 20% own their business. The remaining owners, 

which are 15%, their main source of income was from farming. 

48 



16 

14 

12 
Cl) 
Q) 

.hl 10 
a. 
Cl) -0 8 ... 
C 

~ 
Q) 6 Q_ 

4 

Horses Donkeys Mules Cattle [))gs Goats Sheep Ctnens fAJCks Geese 

Species 

Figure 7: The proportion of domestic animals owned by farmers. 

49 



A total of 67% interviewees said that they utilize their horses for 

transport, but the frequency ·ranged from once a week ( 16. 11 % of 

owners) to twice a week (6.5%). 

A total of 9% of owners traveled short distances (between · one _and two 

kilometers) with their horses in one day. A further 6.5% owners traveled 

three to five km and eleven to twenty km in one day with their horses and 

6.3% reported a distance of six to ten kilometers. 

4.5.2 Management of sick animals. 

A total of 45% of owners ask their friends or neighbors who had 

knowledge of horses when their animals become sick. A further 30% 

treated the animals themselves; 19% reported that they do nothing and 6% 

take their animals to the State veterinarian. 

About 3% of owners made use of Animal Health Inspector, private 

veterinarian and traditional healers for medical help. 

In line with the fact that many owners treat their animals themselves, 39% 

use the herbal or natural products or drugs to treat their animals and 23 % 

use the commercial product purchased from shops. The costs of these 

health treatments were on average of R 100 per month per owner. Other 

costs associated with the horses were fodder (costs range between Rl00 

and R4000 per month per owner) and the health treatment (costs range 

between Rl00 and R2000 per month per owner). 

50 



The owners reported a variety of disease conditions (Figure 8). The most 

common conditions noted were ticks (83% of owners), worms ( 45%) and 

hoof problems (19.4%). 

4.5.3 Nutrition of horses 

Horses belonging to 90% of the owners were given Lucerne hay all year 

round. Further 6% of owners fed their horses on mealies and 4% of 

owners gave their animals concentrate commercial food. The veld in the 

village was utilized by 84% and 16% let their horses graze at roadside. 

During winter, 83.9% of owners reported the condition of their animals 

being poor and only 16. l % reported them being average. During summer 

90.3% of owners reported the condition of their animals being good and 

only 9. 7% their animals being excellent. All of horse owners ( 100%) 

reported the grazing condition in winter being poor and in summer being 

good. 

4.5.4 Breeding of horses 

Many owners initially obtained their horses by breeding (71 %). Twenty 

nine percent of owners owned horses which they inherited. A horse could 

cost anything from R400 to R800 to buy, while most owners claimed that 

they could sell a horse for anything between R500 and RI 000. 

4.5.5 Management of horses 

Many owners (87%) allowed their horses to roam free (along the road or 

in the veld) during the day. A further 13% of owners kept their horses in 

their back yard. Whereas 84 % of the owners kept their horses in a kraal 

51 
. ,._ ,, v,, .... ,, 



!!? 
Ql 
C: 
~ 
0 -0 -C: 
Ql 
(J ... 
Ql 
a. 

104.5 

103.5 

102.5 

101.5 

100.5 

99.5 
Cl) co co • E ~ C G) ... 0 0 E E CIJ 
0 i= "ii a> a, lV 

~ ~ :i5 :i5 a> 
0) 

Q) 0 0 '5 ... ... >- 0. 0. in w - C :, 
0 :i2 0 0 'fl I C/J 

,! 
C 

Condition 

Figure 8: Parasites, veterinary problems and their frequency in horses as observed by 
fam1ers 

52 



or small camp during the night. The remaining percent of owners kept 

their horses tethered and some are roaming free ( along the road or in the 

veld) during the night. 

The majority of horse owners did not report on how their animals increase 

or decrease. Only 22.6 % reported on increase and the increase of 

numbers was in two ways: firstly by birth of fowls (19.4 % of owners) 

and secondly, by horses being bought (3.2 % of owners). 

53 



CHAPTERS 

DISCUSSION AND CONCLUSION 

This study was conducted at Kestell in the northeastern Free State. The 

study area is an established site of University of the Free State Qwaqwa 

campus Parasitology Research Program. 

5.1 Total fecal egg counts 

Souls by ( 1982) states that in horses 500 EPG suggests a mild infection, 

800- 1000 a moderate infection and 1500- 2000 a severe infection. It 

would therefore appear that the horses in the study were severely infected 

with nematodes ( 4400 EPG). Egg counts are influenced by consistency of 

feces and by the total amount of feces passes per day. 

5.2 Strongyle egg count 

The strongy le eggs were the most abundant nematode eggs found with 

EPG values ranging between O and 4400. Since almost of the larval 

cultures contained over 80 % small strongyles, it would stand to reason 

that a high proportion of eggs in fecal egg counts were small strongyle 

eggs. Although more than 40 species of cyathostomes have been 

described in domesticated horses, less than 12 are abundant and common. 

Worldwide, only five species compose 80% to 90% of the total adult 

worm burden (Ohlinger, 1991 ). According to Reinemeyer ( 1986), small 

strongyle ova usually comprise over 95% of the strongylid ova in a horse 

fecal sample. 

54 



5.3 Parascaris equorum egg count 

Parascaris was found in foals of three to nine months of age with EPG 

values ranging between 0 and 208. In horses a marked resistance of 

Parascaris becomes evident after six months of age (Soulsby,1982). Age 

immunity is not dependent on previous exposure to infections (Jacobs, 

1986). According to Soulsby ( 1982) patent infections are of little clinical 

consequence. Researchers working on adult donkeys in Burkino Faso 

(Vercrysse et al., 1986) reported a prevalence of Parascaris eggs of 

23.5% and counts ranging from 100 to 500 EPG. It would therefore 

appear that, it is not uncommon to find Parascaris in adult donkeys which 

correlate with the study done in Kestell where Parascaris was observed in 

faols only. 

5.4 Oxyuris equi egg count 

Oxyuris eggs were found in female and foals with EPG values ranging 

between 0 and 375. This is possibly because of close association between 

females and foals in the herd. Horses frequently engage in mutual 

grooming sessions and this could play an important part in the 

transmission of Oxyuris egg between members of a herd. Male horses or 

jacks may be less exposed to infection with Oxyuris because they tend to 

be more solitary (Wells et al., 1998b). 

5.5 Larval cultures 

Small strongyle larva made up the majority of larvae identified, although 

it was not possible to identify them to genus or species level. Fecal egg 

counts and culture of larvae are used to quantify and differentiate mixed 

infections of gastrointestinal helminths in horses. Accurate diagnosis of 

levels of mixed infection with gastrointestinal nematodes by larval culture 

55 



and differentiation depends on a constant relationship between number of 

eggs present in initial fecal sample and the number of larvae recovered 

from culture, provided culture conditions remain similar (Michael, 1999). 

5.6 Packed cell volume (PCV) 

The normal packed cell volume (PCV) values ranging between 24 and 44 

observed in this study might be due to low level of degree of infection 

with blood sucking helminths, which can influence the pathogenesis of 

gastrointestinal parasitic infection (Holmes, 1987). 

5. 7 Monthly and seasonal averages 

The monthly average total fecal eggs counts were low throughout the 

year. This was also true of the strongyle egg counts. Strongyle burdens of 

horses tend to show a seasonal incidence, which is a reflection of the 

pasture burden of infective larvae (Soulsby, 1982). Soulsby 1982 

demonstrated that mares in Great Britain showed a marked increase in 

strongy le egg output in late spring and early summer and it is also the 

case on Farm 1 at Kestell. 

5.7.1 Parascaris equorum egg counts 

Parascaris showed a peak in winter and also in summer (EPG value of 

about 23 7) but the cause of this is not known. Research on horses in 

Kentucky, USA, showed that the average number of adult Parascaris 

recovered at necropsy was greatest in spring, followed by winter, with the 

other two seasons yielding lower numbers (Lyons et al., 2000). In this 

study it was found that there was a peak in summer and winter and in the 

other two seasons Parascaris was stable. 

56 



5.7.2 Oxyuris equi egg counts 

Oxyuris egg counts were significantly higher in winter only with EPG of 

about 375 and it was stable in summer, autumn and lower in spring. The 

average number of Oxyuris specimens per horse recovered by Lyons et 

al., 1990 in Central Kentucky in the United State of America was also 

higher in winter, second highest in autumn, thereafter spring and summer. 

5.8 Ticks parasitizing horses 

Rhipichephalus evertsi evertsi has a two-host life cycle. The larva to 

nymph moult occurs on one host and the tick passes through more than 

one generation per annum. All stages are present on hosts throughout the 

year, although their abundance may vary from season to season. The tick 

tolerates a wide rage of climatic conditions and is present throughout most 

of the eastern part of southern Africa. Adults of R. e. evertsi are easily 

controlled by localized application of acaricide to the perianal area. It is 

probably only on horses that a sufficient number of adults would ever be 

present to justify the costs of control. No specific control measures are 

usually taken against the immature stages (Coetzer et al., 1994). 

On Farm 1 the number of Ripichephalus reached a peak in June and in 

October 2002 the number was reduced until February 2003. 

5.9 Condition scoring 

Dietary energy intake has a marked effect on ovarian function in a 

number of species of horses (Hatez and Jainudeen, 1974). Body condition 

such as the amount of stored fat in an animal's body, is positively related 

to reproductive performance in cattle (Dunn and Kaltenbach, 1980; 

Croxton and Stollard, 1976; Whitman, 1975; Donaldson, 1969; Lamond, 

57 



1969) and sheep (Polliot and Kilkenny, 1976). Research into the 

relationship between body condition and reproduction in the equine is 

vague and often misconstrued (Henneke, 1981 ). To date, evaluation of 

body condition in horses has no consistent basis and comparison of 

research or management systems considering body condition and 

reproductive efficiency cannot be adequate evaluated (Henneke et al., 

1983). 

The condition scoring system was based on visual appraisal and palpable 

fat cover at six areas of horse's body (Figure 2). During the winter 

months, the presence of a long, heavy hair coat complicated visual 

appraisal, and palpation of the animal was conducted to determine body 

condition more accurately. Some conformation differences made certain 

criteria within each score difficult to apply to specific animals. Some 

horses had more prominent withers and were flatter across the back than 

others. Therefore more emphasis was placed on fat cover over the ribs, 

behind the shoulders and around the tail head when evaluating horses with 

high withers and flat backs. However, when properly applied, the scoring 

system was independent of size or conformation of the horse (Henneke et 

al., 1983). 

Horses from both farms had physical conditions that ranged between 

score 1 & 2 (Table 1 ). The horses were extremely emaciated; spinous 

processes, ribs, tailhead, tuber coxae and ischii projecting prominently. 

The bone structure of withers, shoulders and neck were easily noticeable. 

No fatty tissue was felt. These conditions were observed during winter 

and were probably because grazing conditions was poor. During summer 

the grazing conditions were good and the condition score ranged between 

58 



2 & 3. Horses scoring from 4 to 9 were never observed probably due to 

poor management practices, including lack of good feed supplements and 

absence of anthelmintic treatment. 

5.10 Questionnaire 

The questionnaire was not well received by the horse owners in the 

structured interviews. Owners were suspicious when they were asked 

questions and answers were being written down. They were afraid and 

reported that the researchers will take or hurt their animals. When they 

realize that their animals would not be hurt or taken from them, their 

suspicious turned into interest. 

Horses play a vital role in these resource- limited communities. The 

majority of the owners were pensioners and unemployed and the horses 

provide vital transport. 

A large number of horse owners fed their horses with lucem hay and a 

small percentage gave their horses concentrated commercial food. The 

horse owners also use veld to feed their horses. Water was often supplied 

to the horses when they were still in the yards before they were hitched up 

to work or went to the veld. The owners reported that the conditions of 

grazing and horses during summer were good, whereas during winter the 

grazing conditions were poor. 

The majority of horse owners bred their horses themselves in order to 

increase the number, whereas a small percent inherit them either from 

their family numbers or neighbors. The horse owners within the 

59 



community had business minds; they could buy with a lesser amount and 

sell at a higher price. 

Horses were usually left to roam free during the day, but during the most 

horses owners kept their horses in their back yards. The theft of horses in 

these areas is a major problem. The owners said they knew who was 

stealing the horses; they even organized groups themselves into that 

searched for their lost animals as the police would not do anything about 

their missing horses. 

60 



CHAPTER6 

CONCLUSION 

The conditions for helminth research were unique in this study for two 

reason: firstly the horses had never received anthelmintic treatment of any 

sort, and secondly, because the horses were essentially allowed to roam 

free in herds, and not managed or grouped according to age or sex. The 

findings of this study therefore reflect the natural transmission and 

prevalence of helminths of horses in the study areas. 

Horses of different age groups had slightly different helminth profiles. 

Young horses generally had a high prevalence of strongyle, Parascaris 

and Oxyuris eggs. They appeared not to have the opportunity to 

accumulate large numbers of protozoa Eimeria. As the horse became 

older their levels of Parascaris and Oxyuris decreased. The reason might 

be the animals developing age immunity towards the helminths. 

Investigations on the helminth parasites in South Africa (Scialdo-Krecek, 

1983; Scialdo-Krecek et al., 1983) and Namibia (Scialdi-Krecek et al., 

1983) suggest that in arid environments, a smaller diversity of nematodes 

species is present in the host. In addition, Scialdo-Krecek et al (1983) 

found that there are higher numbers of strongyle in Burchell's zebra in the 

Kruger National Park (387-697 mm annual rainfall). The areas in which 

our horses originated have an annual rainfall of (700- 1340 mm 

annually), that may explain the diversity and abundance (EPG values of 

4400) of strongylid parasites recovered from the horses in this area. 

61 



Parasitism is only one problem in the life of working equid; other 

problems are work, stress, inadequate nutrition and veterinary care. The 

problems with, and solution for effective and appropriate cyathostome 

control in equids are driven by their own unique factors. Veterinary 

services and agricultural co-operatives selling anthelmintics, are far away 

from the community 

Even when anthelmintics are available, owners in these resource-limited 

communities can often not afford dewormers or do not consider them a 

priority when compared to other herd management issues, such as stock 

theft or visible disease agents such as ticks (Wells et al., 1998a and Wells 

et al., 1998b ). Owners should be taught to use body condition scores 

together with appropriate management interventions (such as fecal 

removal) and this may result in more effective nematode control. There is 

a need to understand the owners' perceptions concerning the role of their 

animal health issues if we are to make appropriate recommendations and 

expect them to be adopted by communities. Our knowledge of the impact 

of helminths and disease agents on working equids should allow us to 

develop effective sustainable control strategies for these situations. 

Communities have indicated a need for further information on animal 

health, which has led to training programs for farmers, extension officers 

and other animal users in the sub region and elsewhere. 

The condition scoring system is easy to apply and could be useful in 

experiments on the effects of nutrition and reproductive performance. 

Further the system can be very useful communication tool in managing 

mares to achieve maximum performance (Henneke et al., 1983). 

62 



The questionnaire was the first in the north eastern Free State, South 

Africa to address the need for information concerning the socio-economic 

profile of horse owners living in resource-limited areas. Valuable insights 

into the role of the working horses in the community the management and 

the health of horses were gained. This will allow future workers in this 

area to plan their projects appropriately. It is clear from this project that 

horses perform a vital function in resource-limited communities. 

Future research projects focusing on communal farmers could make a 

valuable contribution to the horses and their owners. Studies to assess the 

use, potential and constraints of horses in the other places of eastern Free 

State should be conducted. Information on basic horse management and 

health needs to be made available to extension officers and owners in 

these areas. Provision of basic veterinary services and the education of 

owners about the correct treatment of their horses is also a priority. In 

response to the shortage of horses, breeding programmes may be an 

appropriate step. 

Future research also should concentrate more on identifying the genus 

present to species level. Although the adults of most species have been 

described and can be identified by a few experts, the morphological 

identification of most larval and egg stages of these parasites is 

impossible. The eggs are morphologically indistinguishable and larval 

stages are generally undescribed (Lichtenfels et al., 1998). 

The present study adds to the existing information on the prevalence, 

diversity and socio-economic factors influencing helminth parasites in 

horses in Africa and equids in general. The specific identities of these 

63 



parasites will contribute to an understanding of their impact on the health 

status of horses as well as to an assessment of the extent of their adverse 

effects. 

64 



CHAPTER 7 

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