Larval cyathostomiasis as a cause of death in two regularly dewormed horses.

Two horses were presented with complaints of chronic weight loss and subcutaneous oedema, one of them presenting diarrhoea. Both animals were grazed with other unaffected horses, all of them being regularly dewormed. Blood chemistry revealed hypoalbuminaemia and a low albumin-globulin ratio. Faecal egg counts were negative and no cyathostome larvae could be found in the faeces. Neither of these horses could be saved, despite intensive treatment. Postmortem examination revealed severe typhlitis and colitis due to numerous inhibited cyathostome larvae.