To carry out studying at a domestic dog of dimensional and population characteristics of nematodes of types of Dirofilaria repens (Railliet et Henry, 1911) and Dirofilaria immitis (Leidy, 1856) in an ecosystem of the region of the North Caucasus. The method of full parasitological and pathoanatomical opening in 2014–2017 at department of veterinary medicine of the Kabardino-Balkaria GAU has investigated 28 corpses of the dogs got in flat, foothill and mountain zones of Kabardino-Balkaria Republic. Dimensional and population morphological and morphometry indicators of nematodes of Dirofilaria repens (Railliet et Henry, 1911) and Dirofilaria immitis (Leidy, 1856) at a domestic dog defined with application of the standard methods of a morphometry of VIGIS (1986), and types of nematodes determined by “Determinant of especially dangerous helminth of animals and the person” under the editorship of V.P. Sergiyev (2010)
Results. In an ecosystem of Kabardino-Balkaria Republic at a domestic dog two types of Dirofilaria – Dirofilaria repens and Dirofilaria immitis which had differences in linear morphometry parameters are revealed, morphological differences it hasn’t been revealed. Average length of polovozrely females of Dirofilaria repens at a domestic dog was 144,7±13,09 mm, and males of – 87,3±9,56 mm. Length of females of Dirofilaria immitis varied within 248–325 mm, and males – 133–194 mm. Width of males and females of Dirofilaria repens varied within 0,9–1,7 mm (on average, 1,10±0,37mm), and Dirofilaria immitis within 1,1–1,9 mm (on average, 1,65±0,42 mm). In Dirofilaria immitis microfilaria size at a domestic dog were less, than Dirofilaria repens microfilaria. Length varied them from 180 to 285 microns, and width – from 4 to 8 microns. Length of a larva at a dog of Dirofilaria repens (Railliet et Henry, 1911) varied from 300 to 360 microns, and its width – from 6 to 10 microns. Conclusion. In flat, foothill and mountain zones of the republic at a domestic dog at types of Dirofilaria repens (Railliet et Henry, 1911) and Dirofilaria immitis (Leidy, 1856) morphological differences aren’t revealed. Had both appearance of Dirofilaria the threadlike body covered with a thin ischerchenny cuticle. The forward end of females and males has been rounded stupidly off. Polovozrely individuals of these bionematodes had dairy or gray-yellow color. Microfilaria Dirofilaria immitis were less, than Dirofilaria repens microfilaria. Had no both appearance of microfilaria at a domestic dog a chekhlik. At Dirofilaria immitis (Leidy, 1856) microfilaria the head end which is rounded off, and tail – pointed. At females of Dirofilaria repens (Railliet et Henry, 1911) the blunt head end was also less intensively painted. The head end of males of Dirofilaria of both types is rounded stupidly off, a gullet of a cylindrical form. The tail end dirofilari conic or rounded off. The uterus occupied all cavity of a body females of Dirofilaria of both types. She is connected by a vagina to an external genital opening (vulva) on the ventral surface of a body. Females of Dirofilaria repens (Railliet et Henry, 1911) and Dirofilaria immitis (Leidy, 1856) viviparous and therefore development of larvae happened only in a uterus.