• horse;
  • lymphoma;
  • weight loss;
  • diarrhoea;
  • T lymphocytes


A 21-year-old pony gelding presented for a 5 week history of diarrhoea, inappetance, progressive weight loss and lethargy. Differential diagnoses for chronic diarrhoea and weight loss in horses include: chronic salmonellosis, sand enteropathy, enterolith, parasitism (strongylosis, cyathostomiasis), NSAID induced ulcerative colitis, inflammatory bowel disease (granulomatous, lymphocytic-plasmacytic or eosinophilic enterocolitis), gastrointestinal neoplasia (lymphosarcoma, squamous cell carcinoma), antibiotic associated clostridial overgrowth, altered diet or bacterial fermentation, peritonitis, Strongylus vulgaris induced arteriopathy (now quite rare) and abdominal mass or abscess. In this gelding, ante mortem diagnosis of CD3+ intestinal large granular lymphoma was made via cytology of abdominal fluid and immunohistochemistry of a rectal muscle biopsy. This report details the clinical, cytological and immunophenotypic findings of a case of large granular lymphoma in a horse.