Anatomical and morphological features of the heart of a domestic dog (Canis Lupus Familiaris L., 1758)
Authors: Ragulya M. R. , Goralskyi L. P. , Sokulskyi I. M. , Kolesnik N. L. , Gutyj B. V. 
Published: April 2024

Cardiovascular organopathology in dogs occurs quite often, but is not fully diagnosed. The occurrence of cardiovascular pathology is due to inadequate physical activity, infectious diseases, injuries, blood loss, diseases of the lungs and other systems, hereditary factors, etc. It is known that prevention, diagnosis, surgical intervention and treatment of these pathologies are impossible without knowledge of the morpho-functional parameters of anatomy, histology and physiology. The cardiovascular system in mammals performs vital functions, ensuring the vital activity of the animal and human body. The cardiovascular system is very plastic in relation to the morpho-functional relationship and has not only pronounced hereditary individual traits, but also the ability to quickly adapt to the changing conditions of the organism's existence. It is one of the first to respond to various natural and anthropogenic factors of the environment and physical stress. The study of the cardiovascular system is an urgent issue today. The aim of the study was to study the morphological assessment of macro- and microstructures of the heart of a sexually mature domestic dog (n = 5), class – Mammalia, species – wolf (Canis lupus), subspecies – domestic dog (Canis familiaris). The completed work is a fragment of the scientific topic of the scientific research work of the Department of Normal and Pathological Morphology, Hygiene and Expertise of the Faculty of Veterinary Medicine of the Polish National University on the topic: “Development, morphology and histochemistry of animal organs in normal and pathological conditions”, according to state registration number No. 0113V000900 and scientific topics: “Features of the morphology of the heart of domestic mammals”, state registration No. 0121U108884. For the work, complex morphological research methods were used: anatomical, histological, organo-, histo- and cytometric, statistical, thanks to which new data on the peculiarities of the macro-, histo- and cytomorphometric characteristics of the morphological structures of the heart in the studied animals were presented. The dog's heart has a rounded shape, its absolute weight is 167.58 ± 9.46 g (without epicardial fat – 154.22 ± 8.04 g), relative weight is 0.72 ± 0.005 %. It was established that the microscopic structure of the ventricles and atria of the dog's heart differ by cytometric indicators, depending on their morphofunctional load. Thus, cardiomyocytes of the left ventricle have the largest volume – 2941.76 ± 127.44 μm3, the right one has a smaller volume – 2237.24 ± 103.02 μm3, and the cardiomyocytes of the atria have the smallest volume – 1496.92±98.02 μm3. The volume of the nuclei of cardiomyocytes of the left ventricle is 64.58 ± 5.09 μm3, of the right ventricle – 59.97 ± 5.83 μm3, the volume of cardiomyocytes of the atria is correspondingly smaller – 53.06 ± 6.02 μm3. At the same time, the nuclear-cytoplasmic ratio of cardiomyocytes of the left ventricle is equal to 0.0224±0.0076, cardiomyocytes of the right ventricle are more important – 0.0275 ± 0.0081, and cardiomyocytes of the atria are the most important – 0.0367 ± 0.0105. We associate such ambiguous cytometric parameters of cardiomyocytes with the morphofunctional activity of the ventricles and the functional features of this myocardial tissue, which is capable of spontaneous rhythmic contractions, as a result of which blood moves through a closed vascular system. Information on the morphology of the heart of a domestic dog, including the results of the study of the macro- and microscopic structure of the studied organs, which are presented in the publication, are of great importance for histology and comparative anatomy, and also make a significant contribution to clinical veterinary medicine.