Evaluation of Myocardial Injury in Acute Canine Monocytic Ehrlichiosis

Twenty eight clinical cases of canine monocytic ehrlichiosis were diagnosed on the basis of buffy coat cytology and evaluated for myocardial injury employing electrocardiography and estimation of cardiac troponin-I before and after standard ehrlichicidal drug (Doxycycline) and supportive therapy. Of 28 dogs with acute symptoms associated with Ehrlichia canis infection, 21 (75%) showed electrocardiographic changes such as sinus tachycardia, sinus arrhythmia, atrial fibrillation, 2^nd degree Mobitz type B heart block, right bundle branch block, atrial premature complexes, ST depression, ST elevation and complex changes as sinus arrest with LVC, sinus arrest with VPC, sinus arrest with ST elevation and LVC, VPC, broad QRS with tachycardia at the time of referral and these changes were resolved after 14 days therapy. Nevertheless, these changes lack specificity to predict myocardial insult as diagnostic sensitivity of electrocardiography (ECG) or echocardiography to diagnose minor myocardial injury is poor. The estimation of cardiac troponin I levels at the time of referral revealed increased levels of cTn-I varying from 0.04–3.36 ng/ml with an average of 1.154 ±0.247 ng/ml and median of 0.92 ng/ml suggesting varying level of cardiac injury in acute monocytic ehrlichiosis in 60.71% dogs (17/28). Unexpected fatal outcome in many cases of canine monocytic ehrlichiosis could possibly be due to cardiac injury. The levels of cTn-I reduced drastically (0.11 ±0.007 ng/ml, range 0.05 to 0.26 ng/ml, median 0.09 ng/ml) on 14^th day post therapy substantiated that there was reversible cardiac injury in dogs with ehrlichiosis due to Ehrlichia canis infection.