Kryvoruchenko D. Canine dirofilariasis (distribution, diagnostics, treatment)

The dissertation theoretically summarizes and experimentally solves the scientific problem of the distribution, diagnosis and treatment of heartworm disease in dogs in the conditions of the city of Kharkiv (Ukraine). The average extensiveness of heartworm infection in dog in Kharkiv city was 28.30 % and the infection intensity was 61.40±4.25 larvae/cm3. The extensiveness of infection (EI) was 26.91 % according to the larvoscopic blood test of dog, and 10.42 % according to the immunochromatographic test of D. immitis antigen. New data on the course of dirofilariasis as part of mixed invasions of the digestive tract of dogs were obtained, and co-infections associated with heartworms were established. According to the results of parasitological studies, heartworm disease occurs in the form of mixed invasions in 74.18 % of dogs, and as monoinvasion in 25.82 % of dogs. A total of 14 associations of heartworms with nematodes, cestodes and protozoa were found, consisting of two (EI – 11.35 %), three (EI – 7.00 %), four (EI – 2.18 %) and five (EI – 0.47 %) species of parasites. The most common co-infections of Dirofilaria spp. were causative agents of helminthiases, namely dipylidiasis (EI – 8.86 %), trichurosis (EI – 8.71 %) and toxocariasis (EI – 8.55 %). Specific features of age and seasonal dynamics, as well as breed susceptibility of dogs to heartworm disease were found. The extentensiveness of infection of dogs by Dirofilaria spp. increases with age and is 13.95 % in young dogs under 2 years of age, 28.08 % in dogs aged 2–5 years and reaches maximum values in dogs aged 5 to 8 years (EI – 41.26 %). The breed susceptibility to the causative agent of heartofilariasis was characterized by the highest EI rates in dogs of service breeds (31.13 %), in mixed breeds (37.74 %) and purebred dogs (32.56 %). Dogs of hunting (25.64 %) and ornamental (18.75 %) breeds were less infested. At the same time, dogs of the Rottweiler breed (EI – 51.52 %), Caucasian Shepherd Dog (47.83 %), German Shepherd Dog (41.51 %), Labrador Retriever (40.54 %), Alaskan Malamute (30 %) were the most susceptible to Dirofilaria spp. French bulldog (16.67 %), American Staffordshire terrier (16.22 %), jagdterrier (13.33 %), boxer (12.50 %), pug (11.11 %) and the Central Asian Shepherd (10.0 %) breeds were less susceptible to the heartworm disease. The seasonal dynamics of heartworm disease in dogs was characterized by the peak of infestation in the spring and summer (EI – 28.65–39.27 %) and a decline in the autumn and winter (EI – 27.70–11.90 %). A method of staining D. immitis nematodes is proposed, which is simple and easy to perform, does not require expensive reagents and special preparation, and is convenient. The method allows to illuminate the cuticle of the nematode with subsequent coloring of its morphological body structures, which increases the effectiveness of morphological and morphometric studies, as well as the accuracy of identification of this species. The most optimal time for a high degree of staining of D. immitis nematodes was experimentally determined to equal 80 minutes. During this period, the degree of staining was high of the head end, esophagus, the part of the transition of the esophagus into the intestine, in females of the head end and vulva, and uterine loops, in males of the head end, short spicule, papillae, ornamentation of the cuticle. The degree of staining of the long spicule was average. The scientific novelty of the performed work is confirmed by the declarative patent of Ukraine for a useful model: “Method of staining nematodes Dirofilaria immitis”. New data on the morphometric identification features of nematodes of the species Dirofilaria immitis were obtained, expanding the already existing data on the peculiarities of the morphological structure of dirofilaria of this species and their differential diagnosis. The conducted morphological studies established that the most characteristic differential features of males are the presence of two unequal spicules, specifically located in relation to each other, as well as well-defined preanal and less pronounced adanal and postanal papillae. In female heartworms, the shape and location of the vulva are characteristic morphological features. A difference in the structure of the esophagus in males and females was observed. In females, the anterior and posterior sections of the esophagus are well defined and enlarged, in males these sections are not defined. In order to improve the efficiency of the species identification of D. immitis nematodes, it is proposed to use metric parameters that characterize the overall size of the body, the width of the body and esophagus in different areas, the length of the esophagus, and also indicate the location of the nerve ring.