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Background and Aim: Anthelmintics are used to control equine nematodes. However, helminth resistance to regularly used drugs is a well-known challenge. Among tests to assess effective control and monitor resistance, the most common is the fecal egg count reduction test (FECRT). In the absence of reliable FECRT results, the nematode egg reappearance period (ERP) is taken into account. This study aimed to examine horses from farms around the Moscow Region to assess nematode resistance through ERP after therapy. Materials and Methods: In the first stage, fecal samples from 280 horses were examined by the flotation method with a sodium nitrate solution. The eggs per gram (EPG) in feces were counted using the modified McMaster technique. One hundred and forty out of 280 horses were selected for further work. Five groups were formed: Two groups of horses infected with strongyles (n = 50) and three groups with Parascaris equorum (n = 90). Therapy against strongyles was performed with albendazole and ivermectin. Therapy for parascaridosis was performed with fenbendazole, ivermectin, and aversectin C. Samples from the horses in each group were taken on the 14th day (2 weeks), 28th day (4 weeks), 42nd day (6 weeks), 56th day (8 weeks), and 84th day (12 weeks) after treatment, and the amount of EPG in each sample was determined. Results: Overall, nematodes were found in 65% of the horses examined. P. equorum was most frequently recorded (42.1%) followed by Strongylidae gen. spp. (27.9%). The strongyles ERP after therapy with albendazole and ivermectin was estimated on 42 days (6 weeks). The growth of P. equorum eggs in the feces was observed from the 56th day (8 weeks) after therapy with fenbendazole, from the 42nd day (6 weeks) after therapy with ivermectin, and was observed from the 84th day (12 weeks) after the use of aversectin. Conclusion: Our study shows widespread reductions in nematode ERPs across the Moscow Region after ivermectin therapy in horses, suggesting that additional monitoring of these farms is needed for effective control of anthelmintic resistance.

The purpose of the research is to outline the growing problem of anthelmintic resistance of horse nematodes in the world, to describe the methods currently used to detect it, and the proposed ways to overcome it.Materials and methods. A review of the world literature on the resistance of horse nematodes to anthelmintic drugs is carried out.Results and discussion. Currently, veterinary parasitology is faced with the growing problem of the emergence of resistant races of helminths, against which previously tested anthelmintic drugs in recommended doses are ineffective. This phenomenon has been noted in many animal species and manifests itself in relation to many drugs of the main groups of anthelmintics. This is evidenced by numerous reports. In horse breeding, benzimidazoles have been used for over 40 years, leading to widespread resistance to them in intestinal nematodes. There is a loss or weakening of the effectiveness of treatment of nematodes of horses with anthelmintic drugs: thiabendazole, pyrantel pamoat, drugs from the benzimidazole groups and macrocyclic lactones. There is no doubt that a similar situation of the spread of resistant races of helminths is also typical for Russia, since here the same anthelmintic drugs are used for treatment as abroad. However, this problem in our country remains practically unexplored. In this situation, the uncontrolled use of anthelmintics, which does not take into account the possibility of resistance to them, inevitably leads (and possibly in some cases has already led) to the emergence and spread of resistant populations of helminths, against which existing drugs will be ineffective.

ABSTRACT. Contemporary American bison (Bison bison (Linnaeus, 1758)) and European bison (Bison bonasus (Linnaeus, 1758)) are introduced (alien) species at the territory of Prioksko-Terrasny Nature Reserve. Presently, extensive interchange of parasitic fauna between the bisons and aboriginal ungulates is recorded, therefore, monitoring their helminth fauna appears to be a pressing issue. The current paper presents a survey of the helminth fauna in American bison and European bison based on the results of original research and literature data analysis. The investigation of faeces samples of American bisons from the nature reserve revealed eggs of Trichostrongylus sp. with length of 78.5 µm and width of 40 µm in size as well as those of Strongyloides papillosus (Wedl, 1856) with length of 60 and width of 20-22 µm in size. The eggs of Strongyloides papillosus in bisons from the nature reserve are recorded for the first time. It is supposed that the bisons contract this nematode species from sika deer (Cervus nippon Temminck, 1838), yet previously it was believed that deer and bisons are safe for each other in terms of helminthic infections. The study has shown the heterogenous composition of helminth fauna in contemporary American bison and European bison in different parts of their range, which appears to be connected with the circulation of helminthes among deers and bisons populating a particular area. The absence of highly specific, high-avid helminthes in the bisons has been found. 1758)) на территории Приокско-Террасного заповедника являются интродуцированными (завезен-ными) видами. В настоящее время идет активный взаимообмен паразитофауной между ними и аборигенными копытными, что делает актуальным мониторинг их гельминтофауны. В статье приводится обзор гельминтофауны бизонов и зубров, основанный на результатах собственных исследований и анализе литературных данных. При исследовании проб фекалий от бизонов с территории заповедника были обнаружены яйца Trichostrongylus sp. длиной 78.5 µm и шириной 40 µm, а так же яйца Strongyloides papillosus (Wedl, 1856) длиной 60 µm и шириной 20-22 µm. Яйца Strongyloides papillosus у бизонов Приокско-Террасного заповедника регистрируется впервые. Предполагается, что заражения бизонов данным видом нематоды происходит от пятнистых оленей (Cervus nippon Temminck, 1838). Ранее считалось, что олени и бизоны безопасны друг для друга в гельминтологическом отношении. Исследование показало неоднородность состава гельминтофау-ны современных бизонов и зубров в различных частях ареала, что связано с циркуляцией гельмин-тов между копытными и бизонами, обитающими на конкретной территории. Установлено отсут-ствие у бизонов видоспецифичных гельминтов.

учебно-методическом пособии изложены методы прижизненной диагностики паразитозов животных, а именно классические методы копрологической диагностики с учетом современных рекомендаций и предложений. Приведены основные возбудители разных видов животных, которые диагностируются при исследовании фекалий, их морфологические и дифференциально-диагностические параметры. Данное учебно-методическое пособие предназначено для студентов, обучающихся по направлению подготовки 36.05.01 – Ветеринария: специалистов, бакалавров и магистров, для аспирантов, проходящим подготовку в области ветеринарии и паразитологии в качестве дополнительной учебной литературы к проводимым занятиям; для практикующих специалистов пособие подойдет для самостоятельного изучения и применения методов и подходов на практике.