Causes and Diagnostic Significance of Coughing in Dogs with Endocardiosis

Introduction. Endocardiosis is the most widespread acquired cardiac disease in small dog breeds, characterised by the valvular degeneration leading to mitral insufficiency. Progression of mitral regurgitation leads to cardiac remodeling, increased left ventricular filling pressures, pulmonary hypertension and, eventually, myocardial dysfunction. Decreased exercise tolerance, dyspnea, anorexia, and coughing are the most often reported signs in dogs with endocardiosis. Coughing is often reported as the primary clinical sign of congestive heart failure in dogs with endocardiosis. The concomitant respiratory tract disease and compression of the left mainstem bronchus by the giant left atrium have also been suggested as the potential causes of coughing in these patients. However, the absence of relief from cough in dogs with endocardiosis when treated with calcium sensitizers and the registered improvement in systolic cardiac function makes doubtful the cardiogenic nature of coughing in endocardiosis. In other words, the clinical and diagnostic significance of coughing in dogs with endocardiosis has not been sufficiently studied. The aim of the present research is to determine the frequency of cough incidence in dogs with endocardiosis and to establish the pathognomonic nature of this symptom in endocardiosis, its clinical significance. Materials and Methods. The medical records of 49 dogs that have attended to the veterinary clinics of the “Vita” network (Rostov region) for cardiological examination in the period from September 1, 2021 to July 31, 2024 were analysed. The research was carried out using the following equipment: premium ultrasound scanner with improved image quality on the ZST+ Mindray Vetus 9 platform, Maxivet 400 veterinary X-ray digital DR system, and Poli-Spectrum–8/V computerassisted electrocardiograph. Results. The research allowed us to find out the following: although the cardiomegaly and the increase in the size of the left ventricle in endocardiosis can aggravate and intensify the clinical manifestation of coughing in dogs with degenerative diseases of the upper respiratory tract, they are not the necessary condition for the occurrence of coughing. Coughing in dogs with endocardiosis should be considered as a clinical sign of the concomitant inflammatory or degenerative disease of the upper respiratory tract, which should be taken into account in therapy and in the attempt to improve the quality of life of these animals. Discussion and Conclusion. We have found that only 57% of the dogs with clinically evident endocardiosis suffer from coughing, whereas it does not have the uniform nature. In dogs with cardiogenic pulmonary edema, a cough is not loud, is usually acute and is associated with the flow of fluid into the medium and large-sized bronchi. The chronic loud, hoarse cough, intensifying in the morning, is typical for dogs with endocardiosis and chronic bronchitis: these animals at the same time have the non-specific inflammatory lesion of the bronchial tree and lesion of the mitral valves. Most severe coughing, with the characteristic loud sound, is observed in dogs suffering from the elements of the upper respiratory tract collapse and cardiomegaly due to endocardiosis.