H. Platt

Aetiological aspects of abortion in the Thoroughbred mare

Abstract Abortion in the Thoroughbred mare has been studied from the standpoint of its statistical incidence and the factors that predispose to its occurrence. The pathological findings in a series of aborted foetuses submitted for autopsy are described. Some aspects of the aetiology of abortion in the mare are discussed.

Alimentary lymphomas in the horse

A series of 9 cases of primary diffuse alimentary lymphoma of the equine small intestine is described. Clinically, the principal effects were attributable to malabsorption and disordered alimentary function and several cases had severe anaemia; in four this was of the haemolytic type. Hypoalbuminaemia and elevated gamma globulin levels were often present. The neoplasms were confined mainly to the small intestine and mesenteric lymph nodes, sometimes with some involvement of other lymph nodes as well. The large bowel was affected in one horse, but none of the cases showed detectable invasion of parenchymatous organs. Evidence is presented that some of these lymphomas were of follicle centre cell origin and it is suggested that they had probably arisen from B lymphocytes in gut-associated lymphoid tissue.

Chronic inflammatory and lymphoproliferative lesions of the equine small intestine

A retrospective study was made of 20 horses with severe and extensive chronic disease of the small intestine. Many of the animals had clinical evidence of malabsorption, with progressive loss of weight, hypoalbuminaemia and sometimes anaemia. All but two of the horses were Thoroughbreds. The pathology was diverse. Nine of the cases were alimentary lymphomas (Platt, 1986) and five had lymphocytic and eosinophilic infiltrations in the bowel wall which were considered to be probable reactions to parasitic invasion. One had acute thrombosis associated with partial occlusion of the anterior mesenteric artery by a verminous thrombus, superimposed on granulomatous lesions resulting from earlier ischaemic episodes. Two animals, from one stud, had dense mononuclear infiltration of the intestinal mucosa with villous atropy accompanying an unidentified acid-fast bacillary infection in the mesenteric lymph nodes and other sites. Three horses had granulomatous or lymphogranulomatous infiltration of the small intestine accompanied by marked mucosal and villous atrophy. One of these had multiple abscessation in part of the affected bowel. Only the three latter cases had lesions resembling those of equine granulomatous enteritis and the results of this study indicate the rarity of this condition in Thoroughbreds in Britain. The different types of lesion were only distinguishable by histological examination, since their clinical effects and gross pathology were not characteristic.

Caecal rupture in parturient mares

Abstract The pathology of 4 cases of caecal rupture in foaling mares is described. One of these animals died suddenly, probably when rupture occurred, and 3 survived for 5 to 8 h and died from acute peritonitis. The pathogenesis of this type of injury is discussed and it is suggested that rupture may arise from the pressure of a foetal hind foot against the caecum when distended by local tympany.

Clinical and pathological observations on generalized steatitis in foals

Abstract A form of generalized fat necrosis and steatitis occurs in pony and donkey foals. The clinical and pathological features of this disorder are described and its possible relationship to a similar condition in the Thoroughbred foal, and to yellow Fat Disease in other species, is discussed.

Observations on the pathology of non-alimentary lymphomas in the horse

A retrospective study was carried out on post-mortem and biopsy tissue samples from 26 horses with non-alimentary lymphoma. On the basis of their histopathology and cytology, the cases were grouped into several categories: (1) Lymphoblastic lymphomas (6 cases) and primary lymphoblastic leukaemia (2 cases). (2) Histiolymphocytic lymphomas involving the skin (6 cases) or lymph nodes (3 cases). (3) Lymphomas showing follicular development (4 cases). (4) Plasmacytic lymphomas (4 cases). (5) Lymphocytic lymphoma (1 case). Most affected horses were middle-aged or old but lymphoblastic neoplasms tended to affect younger horses than other forms. The course of the disease was highly variable. The most rapidly progressive forms were of lymphoblastic cytology, whereas some cases with histiolymphocytic skin nodules appeared to be only slowly progressive. Further information is needed on the pathology and clinical behaviour of some types of lymphoma, particularly those manifesting in the skin. Elucidation of the histogenetic relationships of the different cytological types of lymphoma will involve the development of immunohistochemical and other techniques which are specifically applicable to the horse.