The review article highlights the scientifically proven facts about the spread of toxocarosis invasion in dogs. The problem of toxocarosis is important both for humane and for veterinary medicine. Currently data has already been provided on the etiology and factors for the transmission of toxocaron invasion from the dog to the person. In recent years, there has been a tendency in Ukraine to significantly spread this invasion, which is due to a violation of sanitary-epidemiological surveillance, improper conditions of maintenance, an increase in the number of homeless animals that are carriers of the agent of this invasion. The pathogenic effect of helminths on the host organism is due to mechanical, toxic and inoculatory effects, as well as reflected in physiological processes, morphofunctional characteristics of organs and tissues. Local damage to organs, loss of nutrients, development of a stress state, cytogenetic disorders and changes in the immune status are far from complete list of consequences of toxocaronal invasion. The pathogenesis of toxocarosis is complex and consists of several factors due to the complex interaction of the «parasite host» system. The maximum exposure to toxocarosis is established in puppies up to 6 months of age – 85%. The extent of invasion in animals 6–9 months of age (61.5%) was lower as well as at the age of 9–12 months, which is 45.4%. In the future, the rates of their invasiveness decreased with the age of dogs (25% at the age from 1 to 2 years). The lowest level of invasiveness was recorded in adult animals, predominantly in pregnant females over the age of 3 years (11%).It was found out that in females this infection was registered more often (54.8%) than in males (45.3%). Having analyzed the given domestic literature data, we found that the influence of toxocaronal invasion on the protective systems of the organism of invasive dogs has not been fully studied and requires some refinements. The research of the system of antioxidant protection of the organism of dogs against the background of toxocar are relevant and necessitate in-depth study. Separate fragments of experiments will be published in the following publications.

The aim of the study was to determine the state of the dogs' immune system in experimental toxocariasis. The work was performed during 2017-2020 at the Department of Parasitology and Ichthyopathology in Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies Lviv. The 12 dogs aged 2 to 4 months were used for research studies. Two groups were formed of six animals in each: control and experimental. Puppies of the experimental group (E) were infected with the causative agent of toxocariasis at a dose of 5000 invasive eggs of Toxocara canis per kg of body weight. The control puppies were clinically healthy. At the clinical display of toxocariasis invasion at dogs the cellular, humoral and nonspecific links of the immune system are suppressed and the secondary immunodeficiency comes. Suppression of cellular immunity was accompanied by a decrease in the T- and B-lymphocytes count in the blood of dogs of the (E) group, which indicates the suppression of the lymphoid immune system and a reduction in the resistance of animals. Along with the fall in cellular immunity in infected puppies, suppression of the nonspecific immune system was established, which is manifested by a decline in the phagocytic activity of neutrophils and a decrease in the phagocytic index. Thus, on the 15th and 20th days of the test, the phagocytic activity of neutrophils reduced to 1.6 and 3.9 %, while the phagocytic index – to 5.4 and 6.9 %, respectively. In the study of antimicrobial activity of serum of infected dogs, T. canis found inhibition of bactericidal and lysozyme activity, which reflects the suppression of the physiological state of the humoral immune system of animals with the development of toxocariasis. On the 25th day of the research, a deccline in BABS to 24.0 ± 2.7 %, while in the (C) group of dogs this figure was 30.6 ± 1.9 %. The lowest LABS was on the 25th day of the (E) in animals that were experimentally infected with the pathogen toxocariasis, where compared with the (C) group, this figure decreased by 6.0 %, respectively. The high level of CIC in the serum of dogs infected with T. canis indicates the suppression of the immune system of their body due to the accession of specific antibodies to the products of metabolism of toxocara, which act as antigens.

The problem of toxocariasis is essential for both human and veterinary medicine. Therefore, the study aimed to determine the effect of fenbenzyl and fenbendazole on the morphological parameters of the blood of dogs, with experimental infestation with the pathogen toxocariasis. The experiments were performed on 18 dogs, two to four months of age, and three groups of six animals were formed in each: control and two experimental groups. Puppies of all groups were experimentally infected with toxocariasis at a dose of 5,000 invasive T. canis eggs per kg body weight. The control group of dogs was as untreated control. Puppies of the first experimental group were fed the drug “Fenbendazole” at a dose of 150 mg per 3 kg of animal weight once a day for three days in a single dose. Puppies of the second experimental group were fed Fenbenzyl at a dose of 350 mg per 3 kg of animal weight once a day for three days. It was found that the use of fenbendazole in infected dogs, the number of erythrocytes and hemoglobin in their blood increased compared with the control group but did not reach physiological values. In the second experimental group of animals treated with fenbenzyl, an increase in these indicators was found throughout the experiment. On days 25 and 30 of the experiment, the number of erythrocytes and hemoglobin fluctuated within physiological values. When prescribing drugs “Fenbendazole” and “Fenbenzyl” found a decrease in leukocytes from 10 days of the experiment. In the second experimental group, the number of leukocytes was more likely to decrease than the control group. Such changes in the blood are due to the antiparasitic effect of the drug “Fenbenzyl” and the cessation of toxins of Toxocara on the bone marrow. It was found that the number of eosinophils, neutrophils, and monocytes in animals was significantly reduced in all experimental groups compared to uninfected, infected dogs. It should also be noted that the number of lymphocytes in the blood of dogs of the experimental groups probably increased from the 15th day of the experiment. On days 25 and 30 of the experiment, an increase in the number of lymphocytes to physiological values was found in dogs treated with Fenbenzyl. Thus, the use of fenbenzyl in the second experimental group of dogs helped restore blood morphological parameters to the level of control, which, in our opinion, is due to reduced immunosuppressive effects of Toxocara on their body, as well as hepatoprotective, immunostimulatory, and antioxidant effects of milk thistle.

Toxocariasis is a chronic helminthic disease caused by the larval stages of the nematode Toxocara canis. The problem of toxocariasis is important for both humane and veterinary medicine. Therefore, the aim of the study was to investigate the effect of fenbenzyl and fenbendazole on the intensity of lipid peroxidation in the blood of dogs during experimental infestation with the pathogen toxocariasis. The experiments were performed on 18 dogs, two to four months of age, and three groups of six animals were formed in each: control and two experimental groups. Puppies of all groups were experimentally infected with the pathogen toxocariasis at a dose of 5.000 invasive T. canis eggs per kg of body weight. The control group of dogs was as untreated control. Puppies of the first experimental group were fed the drug “Fenbendazole” at a dose of 150 mg per 3 kg of animal weight once a day for three days in a single dose. Puppies of the second experimental group were fed the drug “Fenbenzyl” at a dose of 350 mg per 3 kg of animal weight once a day for three days. In the clinical manifestation of the disease, toxocariasis secretes metabolic products that promote the formation of large amounts of free radicals, which in turn enhance the initiation of lipid peroxidation processes. With the use of fenbendazole and fenbenzyl, a probable decrease in these products was found starting from the 15th day of the experiment. It should be noted that the lowest level of diene conjugates and TBA-active products was in the blood of dogs of the second experimental group at 25 and 30 days of the experiment. Inhibition of lipid peroxidation processes in the treatment of dogs with fenbenzyl is due to the activation in animals of metabolic processes involving enzymes, including antioxidant enzymes that catalyze the processes of peroxidation and phosphorylation, as well as enhancing erythropoietic function. On the 30th day of the experiment, the level of diene conjugates in the blood of the second experimental group was 0.29 ± 0.02 IU/ml, and TBA-active products – 25.2 ± 0.40 μmol/l.

The aim of the study was to investigate the effect of toxocariasis invasion on protein-synthesizing function and functional state of the liver of dogs. For experimental studies, 12 dogs aged from two to four months were used and two groups of six animals were formed in each: control and experimental. Puppies of the experimental group were experimentally infected with the pathogen toxocariasis at a dose of 5,000 invasive eggs of T. canis per kg of body weight. The control puppies were clinically healthy. Protein-synthesizing function of the liver of dogs in experimental toxocariasis was studied by the level of total protein and its fractions. It was found that on the 25th day of the experiment the level of total protein in the blood of the experimental group of dogs was 56.9 ± 1.47 g/l, while in the control group – 63.8 ± 2.92 g/l. The lowest level of the studied indicator was on the 30th day of the experiment in the blood of the experimental group of dogs, where it decreased by 9.6 %. The results of a study of protein fractions in the blood of dogs infested with toxocara showed that the percentage of albumin is likely to decrease. However, in the blood of infected dogs in this period of research there was a probable increase in globulin levels. The study of the effect of toxocariasis invasion on the activity of enzymes in blood serum is a test for the morphological and functional state of tissues and organs. Based on the studies, it was found that with the development of toxocariasis invasion in dogs there is an increase in alanine aminotransferase in their serum. On the 25th and 30th day of the experiment, the activity of the enzyme in the serum of infected dogs was the highest, where compared with the control group of dogs, the activity of ALT increased by 51.2 and 59.1 %, respectively. Similar changes in activity were observed in the determination of aspartate aminotransferase, where, respectively, on the 15th, 20th and 25th day of the experiment, the activity of AST in the serum of infected dogs increased by 19.3, 27.5 and 39.1 %.