The occurrence of resistant strains of equine parasitic nematodes in Russia

Nematodes are the most commonly reported parasites of horses. Due to the regular use of anthelmintic drugs to control parasitic diseases, there are preconditions for the development of anthelmintic resistance (AR). We have studied AR Strongylidae gen. spp. and Parascaris equorum to fenbendazole and ivermectin fecal egg count reduction test (FECRT) in central Russia. The study included 232 horses from horse farms and from private owners in Moscow and the Moscow region. The horses were naturally infested with nematodes. The count of eggs per gram (EPG) of feces was ≥180. The FECRT value of strongylid horses to fenbendazole in the equestrian center (ESC) in Moscow was 68.7%, FECRT in the breeding farm in Dubna was 79.1%, FECRT in the ESC in Zelenograd was 86.3%. AR strongylid horses to ivermectin was noted in Moscow (FECRT=85.7%) and in the Ramensky district of the Moscow region (FECRT=88.8%). AR of P. equorum to fenbendazole was FECRT=88.2% in Dubna. FECRT=78.6% P. equorum to ivermectin from private owners in the Moscow region. Thus, AR of horse nematodes to fenbendazole and ivermectin was revealed in the territory of central Russia. This indicates the need for additional control over the development of AR in these farms and in Russia.