Treatment of Equine Parasitic Infections with Ivermectin

To achieve the research objectives, the following tasks were formulated:

• to study the effect of the injectable antiparasitic product Ivermek on the horse body via intramuscular and oral administration
• to study the anthelmintic activity with different administration routes
• to study the efficacy of the product against equine gasterophilosis.

The study on the effect of Ivermek on the horse body was conducted on 48 horses of various age and sex groups and different breeds at two farms in the Novouzensky District of the Saratov Region (Russia).

All animals were divided into groups based on the principle of analogs (8 groups of 6 animals). The product was administered intramuscularly (groups 1-4) at doses of 0.1, 0.2, 0.4, and 0.6 mg/kg body weight (active ingredient), and orally (groups 5-7) at doses of 0.2, 0.5, and 1.0 mg/kg body weight (active ingredient) as a single treatment. The animals in the 8th group served as the control and did not receive the product.

Throughout the experiment, the animals were kept under identical feeding and housing conditions. During the trial, the general health status, appetite, condition of the skin and mucous membranes, and behavior of the animals were monitored. Clinical observations and behavioral responses were recorded daily for 7 days following product administration. In addition, the cardiovascular and respiratory systems were examined, and hematological parameters were evaluated. Blood samples were collected from the jugular vein one day prior to, and 1, 3, and 5 days after drug administration. Using standard techniques, erythrocyte and leukocyte counts, hemoglobin levels, and the leukocyte differential were determined.

Further research on the anthelmintic efficacy of Ivermek against equine helminthiases was conducted from March 2002 to July 2007. The study was carried out at several horse breeding farms in the Saratov, Volgograd, Penza, and Novosibirsk regions, as well as the Stavropol and Krasnodar territories (Russia), which are persistently endemic for these parasitic diseases. A total of 1,432 horses of various breeds, ages, and sexes were examined.

The product was administered once intramuscularly at a dose of 0.2 mg/kg of body weight (1 ml per 50 kg) of active ingredient, and orally at the same dose. Special attention was paid to the clinical condition of the animals and their tolerance of the product.

The efficacy of Ivermek was assessed based on the results of coprological examinations using flotation methods, as well as perianal fold scrapings (for oxyuriasis), conducted before and 20 days after drug administration using the "critical test" method.
The study of Ivermek's efficacy against equine gasterophilosis was conducted on 134 horses of various age and sex groups grazing in pastures endemic for this entomosis at farms in the steppe zone of the Saratov and Volgograd regions (Russia). The product was administered once intramuscularly at a dose of 0.2 mg/kg of body weight.

The efficacy of the product was evaluated by the excretion of botfly larvae in the feces after treatment. In addition, a helminthological necropsy of 5 experimental (treated with Ivermek) and 5 control (untreated) animals was performed 14 days after a single treatment, following the "critical test" method. Botfly larvae were collected and counted.

The study results established that Ivermek, when administered to horses both orally (at all tested doses) and intramuscularly (up to 0.4 mg/kg), does not adversely affect the animals. No local or systemic adverse effects were noted; the clinical condition of the animals remained within normal physiological limits. No deviations in the animals' behavioral responses were recorded. In the group receiving a dose of 0.6 mg/kg (intramuscularly), two out of six horses exhibited mild depression and reduced appetite, which resolved within three days of product administration, while one animal showed signs of intestinal colic. Hematological parameters in horses across all groups remained within normal physiological limits. Only in the animals of groups 3, 4, and 8 was a statistically insignificant decrease observed in the erythrocyte count and hemoglobin content compared to pre-trial levels and those of the control animals (down to 7.55-7.77 × 10¹²/ml and 9.12-9.44 g%, respectively, which also remains within normal physiological limits). In the leukocyte differential of the animals in these same groups, a slight left shift of neutrophils and lymphocytosis were noted, although the differences were statistically insignificant.

Thus, the intramuscular and oral administration of this new ivermectin-based formulation at both the proposed therapeutic and elevated doses does not cause any side effects and is safe for horses, with the maximum tolerated dose being 0.6 mg/kg of body weight. Therefore, intramuscular administration of Ivermek at a dose of 0.2 mg/kg of body weight (active ingredient) can be recommended as a broad-spectrum antiparasitic agent for various endo- and ectoparasitic diseases in horses.

As a result of studies on the anthelmintic activity of the new micellar formulation of ivermectin, it was established that the average extensive efficacy of a single deworming in horses was 99.7% with intramuscular administration and 91.9% with oral administration. The obtained results are summarized in the table.

Results of testing the efficacy of Ivermek against equine helminthiases

No adverse effects or complications were observed following the administration of the product.

Thus, Ivermek, when administered as a single intramuscular injection at the therapeutic dose, demonstrates high anthelmintic efficacy against equine helminthiases. Studies on the efficacy of the new micellar formulation of ivermectin against equine gasterophilosis showed that, following a single administration, the massive excretion of gasterophilus larvae began 6 to 8 hours later. Between 25 and 318 larvae per head were collected from the treated animals.

Selective necropsies of the treated animals revealed no botfly larvae in the stomach or intestines, whereas control animals harbored an average of 138 gasterophilus larvae each.

Thus, based on the results of fecal examinations and necropsy data, the 100% efficacy of Ivermek against gasterophilosis was established.

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• Treatment of horses parasitosis by ivermek
• V. A. Sidorkin, G. A. Sulejmanov

The influence of new injectable antiparasitic preparation Ivermek on organism of horses is investigated at intramuscular and per os ways of introduction. It is determined anthelmintic and insecticidal activity. It is established, that Ivermek does not render negative influence on hematological and clinical parameters of horses organism. Efficiency of dehelmintization at the main helminthosis of horses has made 99,4 % at intramuscular and 90,2 % - at per os way of introduction. It is received 100 % efficiency of Ivermek at gastrophylosis.