Equine proliferative enteropathy: a cause of weight loss, colic, diarrhoeaand hypoproteinaemia in foals on three breeding farms in Canada

Proliferative enteropathy (PE) is a transmissible enteric disease caused by Lawsonia intracellularis, An outbreak of equine PE was diagnosed in foals from 3 breeding farms. Most foals had been weaned prior to the appearance o f clinical signs, which included depression, rapid and marked weight loss, subcutaneous oedema, diarrhoea and colic. Poor body condition with a rough haircoat and a potbellied appearance were common findings in affected foals . Respiratory tract infection, dermatitis and intestinal parasitism were al so found in some foals. Haematological and plasma biochemical abnormalities included hypoproteinaemia, transient leucocytosis, anaemia and increased s erum creatinine kinase concentration. Postmortem diagnosis of PE was confirmed on 4 foals based on the presence o f characteristic intracellular bacteria within the apical cytoplasm of prol iferating crypt epithelial cells of the intestinal mucosa, using silver sta ins, and by results of PCR analysis and immunohistochemistry. Antemortem di agnosis of equine PE was based on the clinical signs, hypoproteinaemia and the exclusion of common enteric infections. Faecal PCR analysis was positiv e for the presence of L. intracellularis in 6 of 18 foals tested while the serum of all 7 foals with PE serologically evaluated had antibodies against L. intracellularis. Most foals were treated with erythromycin estolate alone or combined with r ifampin for a minimum of 21 days. Additional symptomatic treatments were ad ministered when indicated. All but one foal treated with erythromycin survi ved the infection. This study indicates that equine PE should be included i n the differential diagnosis of outbreaks of rapid weight loss, diarrhoea, colic and hypoproteinaemia in weanling foals.