Ventricular arrhythmias induced by snake bite in a horse: A case report.

A Mangalarga Marchador mare was referred to treatment with a history of poisoning with evident tachyarrhythmia detected on cardiac auscultation. The electrocardiogram was performed and detected occurrences of paroxysmal monomorphic ventricular bigeminy (pMVB), pMVB with pairs of premature ventricular contractions (PVC) (pMVBPC), and paroxysmal monomorphic ventricular tachycardia (pMVT). In all cases, incomplete atrioventricular dissociation and coupling variation are observed. These characteristics, associated with non-reduction of successive subsequent coupling intervals and the absence of typical characteristics of the Wenckebach phenomenon between PVC occurrences, reinforce the hypothesis of the presence of reentry and rule out the possibility of parasystole. Given the above, this report shows the importance of cardiac evaluations in horses affected by snake bites and, as far as the authors could ascertain, this is the first report on the occurrence of pMVB, pMVBPC in horses and on the description of pMVT caused by snake bites of the genus Bothrops sp.