Anthelmintic resistance in Creole horses in the South of Rio Grande do Sul, Brazil

Abstract

The objective of the study was to evaluate the antiparasitic resistance against horse nematodes in the South of Rio Grande do Sul, Brazil. The results concerning the tests of anthelmintic efficacy on horses, stored in the database of the Parasitic Diseases Study Group (GEEP) - Veterinary Faculty, at the Federal University of Pelotas (UFPel), were carried out in the laboratory from 2018 to 2019. Stool samples were received from farms with breeding of adult female and male Criollo horses naturally infected, located in municipalities in the country’s southern region. The antiparasitic agents tested were Triclorfon + Fenbendazole, Closantel + Albendazole, Ivermectin + Praziquantel, Fenbendazole, Ivermectin, Doramectin, Mebendazole and Moxidectin. Techniques such as Gordon and Whitlock, Coproculture and Fecal Egg Count Reduction Test were performed. Of all the antiparasitic drugs tested, it was observed that only treatments with Ivermectin 2% showed desired values. The observed results indicate that resistance to macrocyclic lactones is usual in equine parasites in this Brazilian region, despite the results with isolated Ivermectin.

A national survey of anthelmintic resistance in ascarid and strongylid nematodes in Australian Thoroughbred horses

“…Resistance to multiple ML drugs, including IVM, ABM and MOX, was observed in cyathostomins in News South Wales and Victoria where most of the Thoroughbred horses are located in Australia. Multiple reports of cyathostomin resistance to MLs have been published in recent years globally ( Nielsen, 2022 ), including Australia ( Abbas et al, 2021 ), Brazil ( Flores et al, 2020 ; Lignon et al, 2021 ; Martins et al, 2021 ), the UK ( Bull et al, 2023 ) and the USA ( Nielsen et al, 2020 , 2022a ). The growing evidence of AR to all available single active ML drugs is concerning as the indiscriminate use of MLs continues on Australian horse properties and elsewhere ( Nielsen et al, 2018 ; Abbas et al, 2023a ).…”

“…Conversely, for cyathostomins, AR is well-established against BZs and THPs and resistance is emerging against MLs ( Peregrine et al, 2014 ; Saeed et al, 2019 ; Nielsen, 2022 ). Recently, resistance in cyathostomins following treatments with moxidectin (MOX) has been increasingly reported ( Nielsen et al, 2020 ; Flores et al, 2020 ; Abbas et al, 2021 ; Lignon et al, 2021 ; Martins et al, 2021 ). This situation is of considerable concern as MOX is often the only effective drug available against encysted larval cyathostomins in addition to 5-day fenbendazole (FBZ) treatment ( Reinemeyer et al, 2015 ; Bellaw et al, 2018 ).…”

Anthelmintic resistance in equine nematodes: Current status and emerging trends

“…It is remarkable that Table 1 contains six Brazilian studies reporting macrocyclic lactone resistance, which is almost half of all studies reporting resistance to this anthelmintic class. Several of these studies documented clearly reduced macrocyclic lactone efficacy in several groups and to several members of this class ( Toscan et al, 2012 ; Flores et al, 2020 ; Martins et al, 2021 ; Lignon et al, 2021 ), and one of them was a terminal study with intestinal worm counts confirming resistance to ivermectin in two cohorts ( Felippelli et al, 2015 ), providing strong evidence for these findings. In 2020, we documented the first case of macrocyclic lactone resistance in equine strongylids in the US ( Nielsen et al, 2020 ).…”

“…Thus, X means that resistance was tested, but not found, and X-AR means that resistance was tested and found. Country Publication Benzimidazoles Pyrimidines Macrocyclic lactones Algeria Boulkaboul et al (2006) X-AR X Australia Pook et al (2002) X-AR X-AR X Abbas et al (2021) X-AR X-AR Belgium Dorny et al (2000) X-AR X-AR Brazil Toscan et al (2012) X-AR Canever et al (2013) X-AR X-AR X-AR Felippelli et al (2015) X-AR Saes et al (2016) X-AR X Vera et al (2020) X-AR X Flores et al (2020) X-AR X-AR X-AR Martins et al (2021) X-AR X-AR Lignon et al (2021) <...…”

Survey on sanitary practices and knowledge about infectious diseases among equine owners in the State of Rio Grande do Norte, Brazil

“…Based on the prepatent period and climatic conditions, treatment is recommended every 2 to 4 months (Losinno et al, 2018). This recommendation seems to have been adopted by the majority of the owners in this study, and as documented by Lignon et al (2021), this approach remains mainly due to the ease of application, acquisition, and cost-effectiveness for breeders.…”