EQUINE VETERINARY JOURNAL
29
Equine vet. J . (1977), 9 (I), 29-31
Liver Fluke Infection in Horses and Ponies J. M. OWEN The Hale Veterinary Group, Chippenham, Wiltshire SN15 IBS
SUMMARY Thirty eight cases of Fasciola hepatica infection in horses with associated clinical signs are reported. A method of examining large amounts of faeces for fluke ova is described. A safe method of treatment for infected horses is given which involves oral medication with oxyclozanide at a dose rate of 15 m1/50 kg body weight.
INTRODUCTION CATTLE and sheep are considered to be the common hosts of the liver fluke, Fasciola hepatica, and there are a number of references to liver fluke in donkeys (Collins, 1961; Mijatovic and Herceg, 1962; Hatch, 1966; Green, Leiper and Green, 1968). The horse, however, has been considered an unusual host along with some other exotic species including the beaver, coypu, elephant, and kangaroo (Lapage, 1956). The purpose of this paper is to record that fluke infection in the horse may not be as uncommon as previously suggested. The types of management and the geographical locations where liver fluke has been found in horses and ponies are described as well as the clinical findings observed in infected animals. In addition a useful laboratory technique for examination of horse faeces for fluke ova is described and details given of safe and effective treatment. History and Clinical Signs Until the very wet summer of 1968 liver fluke was not recognised as a problem in the author’s practice. Neither the acute nor chronic form of the disease was seen in cattle or sheep although liver fluke were occasionally observed in animals during routine autopsies. During the winter of 1968-69 cattle on some of the best dairy farms showed a decrease in milk quality and quantity, a slower recovery from metabolic diseases such as hypocalcaemia and hypomagnesaemia and an increased susceptibility to infection. In these cattle a capricious appetite was frequently observed. Eventually liver fluke infection was diagnosed by finding fluke ova in faecal samples and confirmed by post-mortem examination of livers. The succession of very mild winters since then in the West of England has increased the problem until it is now accepted that liver fluke infection is endemic in cattle in this area, but treatment with a variety of modern drugs is effective if carried out routinely. It is emphasised that very few animals showed the classical signs of fluke infection as described by Lapage (1956) and that the Paper presented at the annual congress of the British Equine Veterinary Association, Oxford, 1975.
problem was suspected on the basis of lowered performance. Hunters and brood mares are owned by many farmers in the author’s practice area, and the pressure for grazing space for the increasing number of horses and ponies is such that most farms have resident equidae, which graze the same pasture as the cattle. As the build up of fluke infection in cattle continued some of these horses showed signs of lowered performance or loss of condition. Horses which were said to be fit became fatigued after working for only half an hour. After this a few normal days would be followed by another listless day. Hunters were seen to take weeks rather than days to recover from a hard day’s hunting. Showjumpers and event horses produced poorer performances than expected and mares lost condition rapidly after foaling. The appetite of such animals varied greatly from day to day for no obvious reason and some developed acute diarrhoea when rations were suddenly increased or changed. Urticaria was seen frequently in horses with diarrhoea. Routine blood and dung samples gave no specific information although slight anaemias were sometimes present and aspartate aminotransferase (AAT) levels were normal. Table I gives details of 6 cases showing clinical signs. The association of these horses with fluke infested pastures was eventually realised and a diagnosis of suspected liver fluke was confirmed by laboratory examination of faeces. Diagnosis Faecal samples were examined initially at the Veterinary Investigation Centre, Gloucester. The technique used at that Laboratory and subsequently by the author was described by Hewitt (1970) to detect very low numbers of eggs in large amounts of faeces. Method: 1) 30-40 g of faeces are washed through a 100 mesh sieve, 20 cm in diameter, with a forced jet of tap water and the filtrate is collected on a 200 mesh sieve. The residue which contains any fluke eggs is washed 2) off the 200 mesh sieve into a 250 ml beaker.
EQUINE VETERINARY JOURNAL
30
TABLE I DETAILS O F 6 CASES OF LIVER FLUKE IN HORSES
Type or Breed
Age (years)
1. Hunter
I1
.-
Signs
Loss of weight when in work. Poor appetite.
No. of horses on farm
Contacts show1 to have fluke ova in faeces
Type of farm
Location of farm and type of soil
7
2
30 cow beef herd
Heavy wet clay a t the foot of a greensand ridge.
___
2. Eventer
9
Diarrhoea and urticaria. Slow recovery from work.
14
5
200 cow dairy herd
Deep loam watermeadow?, liable to flooding in winter months.
3. Poin t-to-Poin ter
9
Loss of weight, variable appetite. Poor performance.
11
2
Intensive pig farm adjacent to dairy farm
High, free draining Cotswold Limestone.
Aged
Loss of condition during pregnancy. Variable appetites.
17
1
80 cow dairy herd
Low lying heavy clav and brash (loose stony soil).
4
Variable performance when ‘fit’. Poor skin.
65
7
Small dairy herd recently sold because of losses due to liver fluke.
Chalk downland.
15
Losing condition. Listless. Poor appetite.
1
1
Vicarage paddock also grazed by cattle.
Limestone brash.
~~-
4. Thoroughbred
Mare 5. Thoroughbred
~
6. Welsh pony
3) 4)
5)
After the contents have been allowed to settle for 2-3 min the supernatant is poured off. The beaker is again refilled, the debris allowed to settle and the water decanted off again. This is repeated until the fluid contents of the beaker are clear, when a final decantation is made leaving about 10-15 ml of water and the non-floating debris. This is then agitated before pouring on to an 8 cm petri dish and examined for fluke eggs under the low power of a microscope. Scanning of the petri dish is made easier if the dish is marked with parallel lines. The presence of one egg in the faeces of a suspect animal is sufficient to advise treatment.
Treatment Oxyclozanide’ was used to treat 38 horses and ponies. It was given orally either as a drench or, diluted with water, by stomach tube, at the rate of 15 ml per 50 kg body weight with a maximum of 100 ml. Seven heavily pregnant Thoroughbred mares have been treated with no adverse effects, but some cases of very mild colic and transient diarrhoea have been observed in some animals. The animals no longer excreted fluke ova after treatment with oxyclozanide. Locat ion Although horses infected with fluke have been found mainly on wet poorly drained pasture it is more important to consider if there is contact with infected cattle or sheep 1 “Zanil” (I.C.I.).
than the type of land on which they are grazing. Experience has shown that horses on relatively dry chalk downland and free draining Cotswold sandstone may become infected with fluke if they are in contact with infected cattle. DISCUSSION Very little information is available as to the incidence of fluke infection in horses. At the Cooper Technical Bureau during 1960 some 33 per cent of donkey faeces showed fluke infestation while only 0.1 per cent of horse samples contained fluke eggs (Pankhurst, 1963). Four out of 20 ponies bought in a Welsh market and subsequently autopsied were found to contain mature fluke in the bile ducts (Flower, 1975). Five out of 14 horses grazing water meadows with a 120 cow dairy herd were found, by the author, to have fluke ova in their faeces. In a survey in the West of Ireland it was found that 91 per cent of donkeys and 77 per cent of horses sampled were excreting fluke ova (Kearney, 1974). The total number of horses and donkeys which were sampled in this survey was not mentioned. Infection may frequently go unnoticed in horses at autopsy. Kearney (1974) reports that there are few, if any, macroscopic lesions even in heavily infected livers and therefore it is likely that infection in horses may be overlooked at post-morten examinations. Diagnosis in cattle is sometimes difficult because a cow known to be infected may excrete fluke eggs one day but not the next. This may also be a problem in horses.
EQUINE VETERINARY JOURNAL
31
Pankhurst (1 963) successfully treated infected donkeys by drenching them with carbon tetrachloride. A mixture of equal parts of 3 4‘5 tribromosalicylanilide and 4‘5 dibromosalicylanilide (Hilomid*) was also used with success on donkeys, by Green, et al. (1968). The finding of 38 infected animals in less than 12 months suggested that fluke infection could be an important cause of poor performance in horses in certain areas. The longevity of the adult fluke could mean that infected horses have lowered performance levels for months after their removal from the source of their infection. REFERENCES Collins, D. R. (1961). Fascioliasis in a Mexican burro. J. Am. vet. med. Ass. 139, 1321-1323. Flower, P. J. (1975). Personal communication. Green, D. A., Leiper, J. W. G. and Green, C. M. (1968). Use of Hilomid against Fasciola hepatica in donkeys. Equine vet. J. 1, 89-90. Hatch, C. (1966). Fasciola hepatica infection in donkeys. Irish vet. J. 20, 130. Hewitt, S. G. (1970). A simple rapid method for .detecting the presence of fluke ova in cattle and sheep faeces. Medium 3, 92-93. Kearney, A. (1974). Fasciola hepatica in equines as reservoir hosts on hill and marginal land. Proc. 3rd Int. Congr. Parasif. Munich 1, 511-512. 2 Astra Hewlett Ltd.
Lapage, G. (1956). Veterinary Parasitology. 1st Edition 267, Oliver & Boyd, Edinburgh and London, Charles C. Thomas, Springfield, Illinois. Mijatovic, I. and Herceg, M. (1962). Histopathology of the liver in donkeys infested with Fasciola and Dicrocoelium. Vet. Arh. 32, 97-99. Pankhurst, J. W. (1963). Liver Fluke in Donkeys. Vet. Rec. 75, 434.
RESUME Trente huit cas d’infestation par Fasciola hepatica avec des signes cliniques sont rapportks. Une mCthode pour examiner de grandes quantitks de feces afin d’y rechercher des oeufs de Douve est indiquke. Le traitement consiste en l’administration orale d’oxyclozanide i la dose de 15 mI pour 50 kilos de poids vif. ZUSAMMENFASSUNG 38 Faille von Befall mit Fasciola hepatica werden beschrieben, bei denen klinische Symptome festzustellen waren. Eine Methode wird beschrieben, mit deren Hilfe grosse Kotmengen auf das Vorhandensein von Leberegeleiern untersucht werden konnen. Eine sichere Methode fur die Behandlung befallener Pferde besteht in der oralen Gabe von Oxyclozanid in einer Dosis von 15 ml pro 50 kg Korpergewicht.
Accepted for publication 20.10.76
ABSTRACT Parasitology Equine Babesiosis: a severe outbreak in a stud farm at Hissar GAUTAM, 0. P. and DWIVEDI, S . K. (1976). Indian vet. J. 53, 546-551. An acute outbreak of Babesia equi infection among a group of recently imported mares is described. The outbreak occurred in an area where the disease was enzootic and horses which had resided on the stud for a considerable period did not develop clinical signs. The occurrence of the disease in July and August was related to the large number of ticks, Hyalomma spp, found on the animals. Intermittent fever, anaemia, jaundice and petechial haemorrhages on mucous membranes were the most common symptoms observed. Symptoms of colic were observed in a proportion of animals. Clinical signs persisted from 3-10 days but in some animals remained from 17-22 days. Post-mortem findings indicated enlargement of the spleen, liver and kidneys, jaundice and the presence of fluid in the thoracic and abdominal cavities. Haemoglobin levels ranged from 7.0-9.4 g/lOO ml, PCV from 16-25 per cent with a total white count ranging from 13.7-24.8 x 109/1showing a marked neutrophilia. Babesia organisms were detected in blood smears and smears prepared from splenic tissues. The disease was confirmed by inoculation of blood from clinical cases into a healthy mare and splenectomised donkeys which subsequently developed parasitaemia. Serological studies were not performed. Forty horses were treated with diminazene diaceturate (Berenil, Hoechst, Germany) 6 mg/kg bodyweight by i.m. injection plus supportive therapy. All horses were sprayed with insecticides. Toxic reactions following treatment were observed and countered with adrenaline and antihistamines. Six animals died following therapy although these were considered to be in an advanced stage of illness by the time treatment commenced. D. POWELL
29
Equine vet. J . (1977), 9 (I), 29-31
Liver Fluke Infection in Horses and Ponies J. M. OWEN The Hale Veterinary Group, Chippenham, Wiltshire SN15 IBS
SUMMARY Thirty eight cases of Fasciola hepatica infection in horses with associated clinical signs are reported. A method of examining large amounts of faeces for fluke ova is described. A safe method of treatment for infected horses is given which involves oral medication with oxyclozanide at a dose rate of 15 m1/50 kg body weight.
INTRODUCTION CATTLE and sheep are considered to be the common hosts of the liver fluke, Fasciola hepatica, and there are a number of references to liver fluke in donkeys (Collins, 1961; Mijatovic and Herceg, 1962; Hatch, 1966; Green, Leiper and Green, 1968). The horse, however, has been considered an unusual host along with some other exotic species including the beaver, coypu, elephant, and kangaroo (Lapage, 1956). The purpose of this paper is to record that fluke infection in the horse may not be as uncommon as previously suggested. The types of management and the geographical locations where liver fluke has been found in horses and ponies are described as well as the clinical findings observed in infected animals. In addition a useful laboratory technique for examination of horse faeces for fluke ova is described and details given of safe and effective treatment. History and Clinical Signs Until the very wet summer of 1968 liver fluke was not recognised as a problem in the author’s practice. Neither the acute nor chronic form of the disease was seen in cattle or sheep although liver fluke were occasionally observed in animals during routine autopsies. During the winter of 1968-69 cattle on some of the best dairy farms showed a decrease in milk quality and quantity, a slower recovery from metabolic diseases such as hypocalcaemia and hypomagnesaemia and an increased susceptibility to infection. In these cattle a capricious appetite was frequently observed. Eventually liver fluke infection was diagnosed by finding fluke ova in faecal samples and confirmed by post-mortem examination of livers. The succession of very mild winters since then in the West of England has increased the problem until it is now accepted that liver fluke infection is endemic in cattle in this area, but treatment with a variety of modern drugs is effective if carried out routinely. It is emphasised that very few animals showed the classical signs of fluke infection as described by Lapage (1956) and that the Paper presented at the annual congress of the British Equine Veterinary Association, Oxford, 1975.
problem was suspected on the basis of lowered performance. Hunters and brood mares are owned by many farmers in the author’s practice area, and the pressure for grazing space for the increasing number of horses and ponies is such that most farms have resident equidae, which graze the same pasture as the cattle. As the build up of fluke infection in cattle continued some of these horses showed signs of lowered performance or loss of condition. Horses which were said to be fit became fatigued after working for only half an hour. After this a few normal days would be followed by another listless day. Hunters were seen to take weeks rather than days to recover from a hard day’s hunting. Showjumpers and event horses produced poorer performances than expected and mares lost condition rapidly after foaling. The appetite of such animals varied greatly from day to day for no obvious reason and some developed acute diarrhoea when rations were suddenly increased or changed. Urticaria was seen frequently in horses with diarrhoea. Routine blood and dung samples gave no specific information although slight anaemias were sometimes present and aspartate aminotransferase (AAT) levels were normal. Table I gives details of 6 cases showing clinical signs. The association of these horses with fluke infested pastures was eventually realised and a diagnosis of suspected liver fluke was confirmed by laboratory examination of faeces. Diagnosis Faecal samples were examined initially at the Veterinary Investigation Centre, Gloucester. The technique used at that Laboratory and subsequently by the author was described by Hewitt (1970) to detect very low numbers of eggs in large amounts of faeces. Method: 1) 30-40 g of faeces are washed through a 100 mesh sieve, 20 cm in diameter, with a forced jet of tap water and the filtrate is collected on a 200 mesh sieve. The residue which contains any fluke eggs is washed 2) off the 200 mesh sieve into a 250 ml beaker.
EQUINE VETERINARY JOURNAL
30
TABLE I DETAILS O F 6 CASES OF LIVER FLUKE IN HORSES
Type or Breed
Age (years)
1. Hunter
I1
.-
Signs
Loss of weight when in work. Poor appetite.
No. of horses on farm
Contacts show1 to have fluke ova in faeces
Type of farm
Location of farm and type of soil
7
2
30 cow beef herd
Heavy wet clay a t the foot of a greensand ridge.
___
2. Eventer
9
Diarrhoea and urticaria. Slow recovery from work.
14
5
200 cow dairy herd
Deep loam watermeadow?, liable to flooding in winter months.
3. Poin t-to-Poin ter
9
Loss of weight, variable appetite. Poor performance.
11
2
Intensive pig farm adjacent to dairy farm
High, free draining Cotswold Limestone.
Aged
Loss of condition during pregnancy. Variable appetites.
17
1
80 cow dairy herd
Low lying heavy clav and brash (loose stony soil).
4
Variable performance when ‘fit’. Poor skin.
65
7
Small dairy herd recently sold because of losses due to liver fluke.
Chalk downland.
15
Losing condition. Listless. Poor appetite.
1
1
Vicarage paddock also grazed by cattle.
Limestone brash.
~~-
4. Thoroughbred
Mare 5. Thoroughbred
~
6. Welsh pony
3) 4)
5)
After the contents have been allowed to settle for 2-3 min the supernatant is poured off. The beaker is again refilled, the debris allowed to settle and the water decanted off again. This is repeated until the fluid contents of the beaker are clear, when a final decantation is made leaving about 10-15 ml of water and the non-floating debris. This is then agitated before pouring on to an 8 cm petri dish and examined for fluke eggs under the low power of a microscope. Scanning of the petri dish is made easier if the dish is marked with parallel lines. The presence of one egg in the faeces of a suspect animal is sufficient to advise treatment.
Treatment Oxyclozanide’ was used to treat 38 horses and ponies. It was given orally either as a drench or, diluted with water, by stomach tube, at the rate of 15 ml per 50 kg body weight with a maximum of 100 ml. Seven heavily pregnant Thoroughbred mares have been treated with no adverse effects, but some cases of very mild colic and transient diarrhoea have been observed in some animals. The animals no longer excreted fluke ova after treatment with oxyclozanide. Locat ion Although horses infected with fluke have been found mainly on wet poorly drained pasture it is more important to consider if there is contact with infected cattle or sheep 1 “Zanil” (I.C.I.).
than the type of land on which they are grazing. Experience has shown that horses on relatively dry chalk downland and free draining Cotswold sandstone may become infected with fluke if they are in contact with infected cattle. DISCUSSION Very little information is available as to the incidence of fluke infection in horses. At the Cooper Technical Bureau during 1960 some 33 per cent of donkey faeces showed fluke infestation while only 0.1 per cent of horse samples contained fluke eggs (Pankhurst, 1963). Four out of 20 ponies bought in a Welsh market and subsequently autopsied were found to contain mature fluke in the bile ducts (Flower, 1975). Five out of 14 horses grazing water meadows with a 120 cow dairy herd were found, by the author, to have fluke ova in their faeces. In a survey in the West of Ireland it was found that 91 per cent of donkeys and 77 per cent of horses sampled were excreting fluke ova (Kearney, 1974). The total number of horses and donkeys which were sampled in this survey was not mentioned. Infection may frequently go unnoticed in horses at autopsy. Kearney (1974) reports that there are few, if any, macroscopic lesions even in heavily infected livers and therefore it is likely that infection in horses may be overlooked at post-morten examinations. Diagnosis in cattle is sometimes difficult because a cow known to be infected may excrete fluke eggs one day but not the next. This may also be a problem in horses.
EQUINE VETERINARY JOURNAL
31
Pankhurst (1 963) successfully treated infected donkeys by drenching them with carbon tetrachloride. A mixture of equal parts of 3 4‘5 tribromosalicylanilide and 4‘5 dibromosalicylanilide (Hilomid*) was also used with success on donkeys, by Green, et al. (1968). The finding of 38 infected animals in less than 12 months suggested that fluke infection could be an important cause of poor performance in horses in certain areas. The longevity of the adult fluke could mean that infected horses have lowered performance levels for months after their removal from the source of their infection. REFERENCES Collins, D. R. (1961). Fascioliasis in a Mexican burro. J. Am. vet. med. Ass. 139, 1321-1323. Flower, P. J. (1975). Personal communication. Green, D. A., Leiper, J. W. G. and Green, C. M. (1968). Use of Hilomid against Fasciola hepatica in donkeys. Equine vet. J. 1, 89-90. Hatch, C. (1966). Fasciola hepatica infection in donkeys. Irish vet. J. 20, 130. Hewitt, S. G. (1970). A simple rapid method for .detecting the presence of fluke ova in cattle and sheep faeces. Medium 3, 92-93. Kearney, A. (1974). Fasciola hepatica in equines as reservoir hosts on hill and marginal land. Proc. 3rd Int. Congr. Parasif. Munich 1, 511-512. 2 Astra Hewlett Ltd.
Lapage, G. (1956). Veterinary Parasitology. 1st Edition 267, Oliver & Boyd, Edinburgh and London, Charles C. Thomas, Springfield, Illinois. Mijatovic, I. and Herceg, M. (1962). Histopathology of the liver in donkeys infested with Fasciola and Dicrocoelium. Vet. Arh. 32, 97-99. Pankhurst, J. W. (1963). Liver Fluke in Donkeys. Vet. Rec. 75, 434.
RESUME Trente huit cas d’infestation par Fasciola hepatica avec des signes cliniques sont rapportks. Une mCthode pour examiner de grandes quantitks de feces afin d’y rechercher des oeufs de Douve est indiquke. Le traitement consiste en l’administration orale d’oxyclozanide i la dose de 15 mI pour 50 kilos de poids vif. ZUSAMMENFASSUNG 38 Faille von Befall mit Fasciola hepatica werden beschrieben, bei denen klinische Symptome festzustellen waren. Eine Methode wird beschrieben, mit deren Hilfe grosse Kotmengen auf das Vorhandensein von Leberegeleiern untersucht werden konnen. Eine sichere Methode fur die Behandlung befallener Pferde besteht in der oralen Gabe von Oxyclozanid in einer Dosis von 15 ml pro 50 kg Korpergewicht.
Accepted for publication 20.10.76
ABSTRACT Parasitology Equine Babesiosis: a severe outbreak in a stud farm at Hissar GAUTAM, 0. P. and DWIVEDI, S . K. (1976). Indian vet. J. 53, 546-551. An acute outbreak of Babesia equi infection among a group of recently imported mares is described. The outbreak occurred in an area where the disease was enzootic and horses which had resided on the stud for a considerable period did not develop clinical signs. The occurrence of the disease in July and August was related to the large number of ticks, Hyalomma spp, found on the animals. Intermittent fever, anaemia, jaundice and petechial haemorrhages on mucous membranes were the most common symptoms observed. Symptoms of colic were observed in a proportion of animals. Clinical signs persisted from 3-10 days but in some animals remained from 17-22 days. Post-mortem findings indicated enlargement of the spleen, liver and kidneys, jaundice and the presence of fluid in the thoracic and abdominal cavities. Haemoglobin levels ranged from 7.0-9.4 g/lOO ml, PCV from 16-25 per cent with a total white count ranging from 13.7-24.8 x 109/1showing a marked neutrophilia. Babesia organisms were detected in blood smears and smears prepared from splenic tissues. The disease was confirmed by inoculation of blood from clinical cases into a healthy mare and splenectomised donkeys which subsequently developed parasitaemia. Serological studies were not performed. Forty horses were treated with diminazene diaceturate (Berenil, Hoechst, Germany) 6 mg/kg bodyweight by i.m. injection plus supportive therapy. All horses were sprayed with insecticides. Toxic reactions following treatment were observed and countered with adrenaline and antihistamines. Six animals died following therapy although these were considered to be in an advanced stage of illness by the time treatment commenced. D. POWELL
