Dirofilariasis of animals and humans is a disease caused by nematodes of the genus Dirofilaria (Railliet et Henry, 1911). The role of wild predators, particularly the red fox (Vulpes vulpes) (Linnaeus, 1758) in the distribution of pathogen of the genus Dirofilaria in the world remains unclear. We studied the occurrence of Dirofilaria immitis (Leidy, 1856) in a population of the red fox. Twenty-seven foxes were examined during the winter hunting season of 2019–2020 in Dergachi district, Kharkiv region of Ukraine. All 27 examined foxes were older than 1.5–2 years old, 5 of them (18.5 %) were 4–5 years old. Dirofilaria immitis was found in 22.2 % of foxes. The intensity of infection ranged from 2 to 4 specimens of nematodes per host. In four foxes (66.7 % of infected hosts), the same number of male and female nematodes was detected, while two foxes (33.3 %) had each 1 male and 2 females of D. immitis. The length of D. immitis males (7 specimens) was 13.96 ± 0.29 cm and the length of females (9 specimens) was 19.58 ± 0.55 cm. Prevalence of infection of foxes with D. immitis presumably depends on their habitat and the presence of mosquitos (vectors of the nematode) in these areas.

Ultrasonic diagnostics is a modern and effective method of laboratory testing of both animals and humans, used for estimation of overall state, and for detection of different pathologies in organs and systems. The aim of the present study was to establish the efficacy of ultrasonic diagnostics of dog dirofilariasis caused by Dirofilaria immitis parasitism, based on several indexes of invasion intensity. It was established that the number of D. immitis helminths found depended on the intensity indexes of microdirafilariasis invasion: using echocardiography, there were no helminths found under the index lower than 40 larvae/cm3. Under the index higher than that, we visualized 1–10 parasite individuals in the cavity of the right ventricle and right atrium, and at the tricuspid valve leaflets. It was established by the results of echocardiography of dogs invaded by D. immitis that the level of invasion intensity impacts significantly on the animals’ heart structure and function, and on their intracardiac hemodynamics. It was proved that under increase of microfilaria number in the blood, heart function deteriorates. Under the invasion intensity lower than 40 larvae/cm3, the changes were characterized by a slight increase in thickness of the posterior wall of the left ventricle in diastole, aorta diameter, left atrium and pulmonary artery (by 6.2%). Under the invasion intensity of 40–60 larvae/cm3, the deterioration in heart structure and function was followed by thickening of the interventricular septum in diastole, posterior wall of the left ventricle in diastole (by 5.6%), increase in ejection fraction index (by 7.0%), widening of aorta root, pulmonary artery, diameter of the left ventricle (by 21.4%), and with increase in indexes of ratio between diameters of the left ventricle and pulmonary artery, and aorta (by 15.6%). Signs of hemodynamic deterioration were established in sick animals, which was characterized by increase of blood speed in the tricuspid valve (by 33.7%), and its decrease in the pulmonary artery (14.1%). Under the invasion intensity higher than 60 larvae/cm3, the aforementioned indexes changed even more significantly. We observed thickening of the posterior wall of the right ventricle in diastole, decrease of the end-systolic size of the left ventricle (by 13.0%), blood speed increase in the aorta and mitral valve (by 12.2%). The obtained results show the necessity of echocardiographic testing of dogs with cardiac dirofilariasis, which allows effective proof of the diagnosis and also helps to understand the overall state of the animal more deeply and to provide it with the appropriate symptomatic cure.

Heartworm disease is a widespread anthropozoonotic disease of carnivorous animals, as well as humans. It is caused by nematodes belonging to the suborder Filariata, family Onchocercidae, genus Dirofilaria. There are about 26 species of heartworms in nature, the most common and pathogenic species in dogs and cats in most countries is Dirofilaria immitis Leidy, 1856. Mature helminths parasitize in the right ventricle and pulmonary arteries, large veins of animals and cause heart and vascular disorders, and death. Therefore, the aim of the study was to investigate the features of morphological and metric structure of adult nematodes of D. immitis isolated from the heart of dogs. Morphological studies have shown that in males the most characteristic differential features are the presence of two unequal spicules, specifically positioned relative to each other, as well as well-defined preanal and less pronounced adanal and postanal papillae. In female heartworms, the characteristic morphological features are the shape and location of the vulva. There is a difference in the structure of the esophagus in males and females. In females, the anterior and posterior parts of the esophagus are well expressed, with enlargements, in males these divisions are not pronounced. To increase the efficiency of species identification of D. immitis nematodes, it is proposed to use metric parameters that characterize the overall body size, body and width of esophagus in different areas, length of esophagus, and the location of the nerve ring. In males, 11 indicators are also suggested that characterize the size of the spicules and the location of the cloaca. In females, seven additional parameters are pointed out that characterize the location of the vulva, anus and body width in these areas. The obtained data expand the already existing data on the peculiarities of the morphological structure of parasitic nematodes of the species D. immitis and their identification.

Полтавський державний аграрний університет 2 Інститут ветеринарної медицини НААН ПОРІВНЯЛЬНА ЕФЕКТИВНІСТЬ СПОСОБІВ ПРОВЕДЕННЯ ІДЕНТИФІКАЦІЇ НЕМАТОД DIROFILARIA IMMITIS Проведеними паразитологічними дослідженнями встановлено високу ефективність запропонованого способу фарбування нематод Dirofilaria immitis, який дозволяє отримати високий ступінь забарвлення та видимості їх морфологічних структур. Спосіб із застосуванням як барвника розчину Люголя перевищував ступінь видимості нематод за мікроскопічного дослідження порівняно із відомими методами із застосуванням 1 %-го спиртового розчину діамантового зеленого та без додавання барвника. Запропонований спосіб призводив до високого ступеня видимості 7 із 9 морфологічних показників у самців та всіх досліджених показників у самок дирофілярій. Отримані дані дозволяють рекомендувати запропонований спосіб фарбування нематод D. immitis з метою підвищення точності їх ідентифікації.

Laboratory diagnostics for any animal pathology refers to special research methods and helps not only in establishing the final diagnosis, but also in expanding data on the course of primary pathology and determining secondary complications based on changes in blood parameters. For this purpose, a clinical study of the blood of dogs with varying degrees of intensity of dirofilariasis invasion was carried out. It was found that the number of erythrocytes decreased in animals of the experimental groups, depending on the intensity of invasion. Severe erythropenia was found in the group of animals with the highest degree of invasion intensity (2.04±0.50 1012/l (p<0.001). It increased with an increasing in the degree of invasion and ESR up to 40.28±12.67 mm/h (p<0.05) and 62.50±14.16 mm/h (p<0.01). Thrombocyto-penia at 199.13±55.31 109/l was found in dogs in the group with the highest degree of invasion. Oligochromemia in animals also depended on the intensity of invasion and was 94.44±12.30 g/l (p<0.05) and 52.00±12.69 g/l (p<0.001). In dogs with the highest number of dirofilaria larvae, the hematocrit was 19.75±6.34 % (p<0.01) and leukocytosis developed (20.53±8.91 109/l). By calculating the leukocyte count in dogs with the highest degree of dirofilariasis invasion, a significant increase in the number of segmented neu-trophils was found to 86.00±10.43 % (p<0.1), eosinophils up to 27.88±5.54 % (p<0.001), basophils up to 1.75±1.39 % (p<0.001), appeared in blood of sick animals young neutro-phils (0.50±1.07 %, p<0.001). The established changes in hematological parameters are associated with the development of hemolytic anemia during invasion and the presence of latent bleeding associated with the destruction of the vascular wall by dirofilariae. The relative leukocytosis, which were diagnosed in sick dogs, is associated with the presence of nematodes and the development of inflammatory processes at the sites of localization and migration of dirofilaria. It is possible that leukocytosis and a shift of the leukocyte formula to the left are associated with intoxication of the body. Key words: dogs, heartworm disease, Dirofilaria im-mitis, blood, erythrocytes, leukocytes, leukocyte formula, hemoglobin, hematocrit, erythrocyte sedimentation rate.