Canine Monocytic Ehrlichiosis (CME), caused by Ehrlichia canis, is a globally prevalent infectious disease known for its complex systemic effects. During the cytopenic chronic phase, previous evidence has identified myocarditis and a high prevalence of arrhythmias. This study provides a detailed evaluation of cardiac biomarkers, electrocardiographic abnormalities, heart rate variability, and survival outcomes in affected dogs.
The research compared 20 dogs with cytopenic CME to 10 healthy controls. Dogs with CME exhibited significantly elevated concentrations of cardiac troponin I (cTnI) and Creatine Kinase-MB (CK-MB), indicating myocardial injury. Although NT-proBNP levels did not differ between groups, clinical signs such as anorexia, vomiting, fatigue, hypoalbuminemia, and heart murmurs were common among affected dogs.
Electrocardiographic findings revealed substantial cardiac dysfunction. Forty-five percent of infected dogs displayed frequent arrhythmias during 24-hour Holter monitoring, including atrioventricular block, ventricular and supraventricular ectopic beats, and sinus tachycardia. One dog experienced 120 episodes of nonsustained ventricular tachycardia and additional sustained events, emphasizing the severity of arrhythmogenic risk.
Heart rate variability (HRV) analysis demonstrated markedly reduced values across key parameters—SDNN, SDANN, and pNN50—proving that chronic CME induces a profound autonomic imbalance. This imbalance reflected heightened sympathetic activity and impaired parasympathetic modulation, consistent with a destabilized autonomic nervous system.
Outcomes were poor: 40% of dogs died during the 28-day treatment period, highlighting the disease’s lethality when cardiac involvement is present. These findings collectively indicate that chronic cytopenic CME is characterized by an arrhythmogenic cardiac profile and severe autonomic dysregulation. Early detection of cardiac alterations may be critical for improving survival in affected dogs.
Source: Filippi, M. G., Ferreira Lima, M. C., et al. (2019). Evaluation of heart rate variability and behavior of electrocardiographic parameters in dogs affected by chronic Monocytic Ehrlichiosis. PLoS ONE. Published May 24, 2019.
