Cardiac arrhythmias identified in horses with duodenitis/proximal jejunitis: six cases (1985-1988).

During a 3 1/2-year period, cardiac arrhythmias were identified in 6 of 67 horses diagnosed with duodenitis/proximal jejunitis (DPJ). Arrhythmias were detected by auscultation of irregular cardiac rhythm and subsequently were characterized by electrocardiographic evaluation. Arrhythmias included frequent second-degree atrioventricular block, ventricular ectopic depolarizations, and atrioventricular conduction disturbance. In 4 horses, arrhythmias resolved with recovery from the primary problem. One horse died suddenly 66 hours after admission, and another was euthanatized at 72 hours after admission. Clinical and laboratory data from horses with DPJ and cardiac arrhythmias (group 1) were compared with findings for horses with DPJ and without arrhythmias (group 2). Group-1 horses had significantly (P less than 0.05) higher serum bicarbonate concentration and serum creatine kinase activity. Normal sinus rhythm returned in all 4 group-1 horses that recovered from DPJ, suggesting a causal relationship between DPJ and the arrhythmias. Two group-1 horses were necropsied, and both had myocarditis. The cause of these lesions was not determined.