Chagas disease is a well-documented cause of infectious myocarditis in humans and can also affect dogs and other mammals. Its etiological agent is Trypanosoma cruzi, a protozoan parasite.
In contrast to human medicine, gastrointestinal infection has never been described in dogs. However, like humans, infected dogs may be asymptomatic or develop cardiac problems. Thus, echocardiography may be a useful tool to diagnose Trypanosoma cruzi, when evaluating arrhythmias. The case here reported proves its utility.
A 16-month-old, spayed, female mixed-breed dog, was presented to a referral institution for assessment of an auscultation abnormality, detected at a primary-care practice. The physical examination was unremarkable but the two-dimensional echocardiography, performed as part of the cardiac evaluation, showed some abnormalities: the left ventricle was mildly dilated, there was an abnormal ventricular septal wall motion and areas of wall thinning were observed at the apex of both ventricles. The electrocardiogram showed a sinus rhythm with frequent premature ventricular complexes and with right bundle branch block. This latter conduction pattern is noted in various human patients, but it is not commonly reported in dogs with Chagas disease.
As this patient did not demonstrate any signs of illness, had previously tested negative for other infectious diseases and was from an endemic area for Chagas disease (south Texas), an immunofluorescence assay to look for T. cruzi was performed. The immunofluorescent antibody titer was positive. This result, together with the verified echocardiographic abnormalities, were the premises to confirm the diagnosis of Chagas myocarditis.
Echocardiography can undoubtedly be useful to reach the diagnosis of this disease and this case report reinforces that, detailing the major cardiac abnormalities identified in this patient.
Stoner and Saunders (2020). Cardiac Manifestations of Trypanosoma cruzi Infection in a Domestic Dog. CASE: Cardiovascular Imaging Case Reports. Elsevier Inc. https://doi.org/10.1016/j.case.2020.06.002