Diarrhoea in horses associated with ulceration of the colon and caecum resulting from S vulgaris larval migration

Abstract

The clinical manifestations of a diarrhoeic syndrome of horses with ulceration of the mucosae of the colon and caecum are described. Patients could be divided into three groups according to their presenting symptoms and the disease is probably caused by the thrombo-embolism associated with migrating larvae of Strongylus vulgaris. The differential diagnosis, prognosis and treatment are outlined with particular reference to the use of antithrombotic agents.

Larval cyathostomiasis (immature trichonema‐induced enteropathy): A report of 15 clinical cases

“…However, in addition to the specific incidents of larval cyathostomiasis previously mentioned, other types of strongyle infection in horses have also been associated with diarrhoeic syndromes. In particular, some authors (Greatorex 1975 ; Merritt et a/ 1975) have stressed the importance of S vulgaris infection as a cause of chronic equine diarrhoea although its precise role still lacks adequate definition. Experimental infections with S vulgaris produce an acute syndrome, with pyrexia, inappetance, depression and severe colic being the main clinical signs.…”

“…Nevertheless it is a widely held view, often supported by a response to larvicidal therapy, that some cases of chronic equine diarrhoea result from diffuse gastrointestinal malfunction induced by large strongyle larval migration (Merritt 1983). Greatorex (1975) described a series of 91 cases of diarrhoea in England which he believed, mainly on clinical grounds and the exclusion of other causes, to be associated with S vulgaris larval migration. Post mortem examination of 35 cases depressed although the globulin component may still be relatively large.…”

“…Leucocyte counts were, however, in the normal range and there was no mention of a seasonal prevalence. As the strongylid burden in Greatorex's (1975) series undoubtedly contained both cyathostomes and large strongyles it is possible that immature cyathostome larvae were involved alone or in combination with S vulgaris larvae in the pathogenesis of the diarrhoea in a proportion. Similarly all horses of the present series examined post mortem had arterial lesions induced by S vulgaris although there was no direct evidence of induced thromboemboli being closely associated with areas of ulceration in the caecum and colon.…”

A Review of the Diagnosis and Treatment of Fluid and Electrolyte Disorders in the Horse

“…Acute salmonellosis is characterised by a marked hypoalbuminaemia and hyponatraemia (as opposed to hypokalaemia) and a mild acidosis, and, there may also be loss of blood directly into the lumen of the gut (Merritt, et af., 1975). Greatorex (1975) also noted blood loss in acute cases of diarrhoea due to S. virlgaris larval migration whereas more chronic cases showed a fall in TSP level. Such hypoproteinaemia is often a feature of chronic diarrhoea (Merritt, et al, 1975).…”

“…Theoretically therefore, dehydrated horses may be either hypokalaemic or hyperkalaemic, depending on the severity of the disorder. Hypokalaemia has been noted in fasted and water deprived horses (Tasker, 1967b) and in animals with experimentally induced diarrhoea (Tasker, 1967c), as well as in horses suffering from diarrhoea caused by the migration of Strongylus vulgaris larvae (Greatorex, 1975). Low intracellular levels of K 1 coupled with normal or raised extracellular levels interfere with membrane depolarisation.…”