Presumptive and reversible left ventricular systolic dysfunction secondary to chloramphenicol administration in a dog

A 6-year-old neutered male 35 kg Staffordshire terrier dog was presented for evaluation of interdigital furunculosis. Culture from lesions revealed meticillin-resistant Staphylococcus pseudintermedius, with susceptibility to only amikacin, chloramphenicol and vancomycin. Chloramphenicol was administered at a dose of 1500 mg orally every 8 hours (42 mg/kg) for a total of 52 days. On Day 52 of treatment, a new mid-systolic click was appreciated on cardiothoracic auscultation that prompted cardiac evaluation. Echocardiogram revealed mild mitral valve prolapse with no mitral valve regurgitation and mild left ventricular systolic dysfunction in multiple indices. Chloramphenicol was discontinued, and a recheck echocardiogram performed 63 days later showed persistent mild mitral valve prolapse and resolution of the left ventricular systolic dysfunction. Reversible left ventricular systolic dysfunction should be considered a potential complication associated with chloramphenicol therapy, and suggests chloramphenicol may need to be used with caution in canine patients with underlying cardiac disease.