Zarytskyi S. Dilated cardiomyopathy due to obesity among domestic dogs (distribution, diagnosis, therapy)

The thesis is aimed at studying the impact of obesity on the development of dilated cardiomyopathy (DCMP) in domestic dogs, its distribution, diagnostic methods, experimental and theoretical substantiation of the effectiveness of the compiled treatment regimen for domestic dogs with this pathology. It was revealed that the most common diseases of the cardiovascular system were: heart failure – 32.6 %, mitral valve mitral incompetence – 21.3 %, arrhythmias – 18.29 %, heart valve stenosis – 14.02 %, dilated cardiomyopathy – 6.84 %, myocarditis – 6.39 % and hypertrophic cardiomyopathy – 0.28 % of animals. The most common pathology of metabolic diseases was obesity – it was suffered by 21.8% of domestic dogs. Dilated cardiomyopathy due to obesity was most often recorded in spring (27.5%) and summer (35.2%) in domestic dogs of the Boxer breed – 18.2%, aged 4–6 years, with an average weight of 40.82±0.5 kg; Doberman – 18.2%, aged 4–7 years, with an average weight of 52.07±1.3 kg; Labrador Retriever – 31.8%, aged 4–8 years, with an average weight of 44.01±1.0 kg; German Shepherd – 31.8%, aged 5–8 years, with an average weight of 46.4±2.6 kg, including 12 males (54.5%) and 10 females (45.4%). The following symptoms were recorded during the clinical examination of domestic dogs with DCMP due to obesity: decreased appetite in 100% of animals, dyspnoea in 50%, rapid fatigue during exercise in 36.4%, cough in 81.8%, tachypnoea in 100%, anaemia of the visible mucous membranes and conjunctiva in 81.8%, muffled heart sounds in 86.3%, blood regurgitation murmur in 90.9%, and tachycardia in 100%. Changes in physiological parameters, namely respiratory rate (RR) and heart rate (HR), were studied. Body temperature in domestic dogs of the experimental and control groups was in the range of physiological fluctuations. The RR (before exercise) in domestic dogs of the Boxer breed was increased by 1.4 times (P<0.05); in the Doberman and Labrador Retriever breeds – 1.3 times (P<0.05; P<0.001); in the German Shepherd breed – 1.4 times (P<0.001), in contrast to the control group of domestic dogs. After exercise, RR was increased by 1.3 times (P<0.05) for the Boxer and German Shepherd breeds (P<0.001); in domestic dogs of the Doberman and Labrador Retriever breeds – 1.5 (P<0.05) and 1.4 times (P<0.001), respectively. The heart rate (before exercise) was higher (P<0.05) by 25.1 % in the Boxer breed; 39.5 % (P<0.05) – in the Doberman breed; 21.1 % (P<0.001) – in the Labrador Retriever breed; 28.2 % (P<0.001) – in the German Shepherd breed, compared to the control group of domestic dogs. After exercise, the heart rate increased by 16.4 % in the Boxer breed (P<0.05); 13.1 % in the Doberman breed (P<0.05); 24.4 % in the Labrador Retriever breed (P<0.001) and by 26.7 % in the German Shepherd breed (P<0.001) compared to the control group. Changes in arterial systolic (P<0.001) and diastolic pressure (P<0.05) were detected, which were 19.6 and 8.5 % lower than those of the control group of domestic dogs. The high informativeness of echocardiography for DCMP due to obesity was established, namely, a decrease in the size of the interventricular septum in diastole (IVSd) by 2 and 2.6 times (P<0.001) in the experimental group of domestic dogs of the Labrador Retriever and German Shepherd breeds; by 1.7 and 1.6 times (P<0.05) in the Boxer and Doberman breeds; reduction in the size of the interventricular septum in systole (IVSs) – by 37.9 and 38.6 % (P<0.001) in the Labrador Retriever and German Shepherd breeds, by 27.5 and 28.1 % (P<0.05) in the Boxer and Doberman breeds. An increase in end–systolic (ESV) and diastolic (EDV) volume was found in the experimental groups of domestic dogs of the Labrador Retriever (P<0.001; P<0.001), German Shepherd (P<0.001; P<0.001), Boxer (P<0.05; P<0.05) and Doberman (P<0.05; P<0.05) breeds. Thinning of the posterior wall of the left ventricle in systole (LVPWs) and diastole (LVPWd) was recorded in the experimental breeds of domestic dogs of the Boxer (P<0.05) and Doberman (P<0.05) and Labrador retriever (P<0.001) and German shepherd (P<0.001) breeds compared to the control group of animals. An increase in the left atrial volume (LA) was significantly recorded in the experimental group of Labrador Retriever and German Shepherd breeds, which was 35.95±0.32 mm (P<0.001), and 36.6±0.63 mm (P<0.001) and the Boxer and Doberman breeds – 31.42±0.74 mm (P<0.01) and 34.98±0.4 mm (P<0.01) compared to the control group of animals. An increase in the size of the transverse aortic section (Ao) in the experimental breed Labrador Retriever by 11.9% (P<0.001) and German Shepherd by 13.6% (P<0.001) was found. As a result, the left atrium to aorta ratio (LA/Ao) had the most significant values only in domestic dogs of the experimental group of Labrador Retriever and German Shepherd breeds (P<0.001).