Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Flores, Ariane Ethur; Osmari, Vanessa; Ramos, Fernanda; Marques, Camila Balconi; Ramos, Denise Jaques; Botton, Sônia de Ávila; Vogel, Fernanda Silveira Flôres; Sangioni, Luís Antônio

doi:10.1590/s1984-29612020086

Cited by 8 publications

(4 citation statements)

References 27 publications

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“…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 ).…”

Section: Cyathostominsmentioning

confidence: 96%

“…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) <...…”

Section: Cyathostominsmentioning

confidence: 99%

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Anthelmintic resistance in equine nematodes: Current status and emerging trends

Nielsen¹

2022

International Journal for Parasitology: Drugs and Drug Resistan

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Section: Cyathostominsmentioning

confidence: 96%

Section: Cyathostominsmentioning

confidence: 99%

Anthelmintic resistance in equine nematodes: Current status and emerging trends

Nielsen¹

2022

International Journal for Parasitology: Drugs and Drug Resistan

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“…In horses, since 2000, AR against BZDs has been evaluated in 58 studies and it was reported in all of them (Nielsen, 2022). Moreover, in horses, multiple resistance to different anthelmintic drug classes has been reported (Flores et al, 2020) and it is quite common to find a population of small strongyles resistant both to BZD and THP (Canever et al, 2013). Another minor mutation was described by Ishii et al (2017) at codon 172 that deserves further research.…”

Section: Ar In Equids: Horses Vs Donkeysmentioning

confidence: 99%

Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections

et al. 2023

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In June 2022, at the XXXII Conference of the Italian Society of Parasitology, the parallels of the main endoparasitic infections of horses and donkeys were discussed. Although these 2 species are genetically different, they can be challenged by a similar range of parasites (i.e. small and large strongyles, and Parascaris spp.). Although equids can demonstrate some level of resilience to parasites, they have quite distinct helminth biodiversity, distribution and intensity among different geographical locations and breeds. Heavily infected donkeys may show fewer clinical signs than horses. Although parasite control is primarily provided to horses, we consider that there may be a risk of drug-resistance parasitic infection through passive infection in donkeys when sharing the same pasture areas. Knowing the possible lack of drug efficacy (<90 or 80%), it is advocated the use of selective treatment for both species based on fecal egg counts. Adult horses should receive treatment when the threshold exceeds 200–500 eggs per gram (EPG) of small strongyles. Moreover, considering that there are no precise indications in donkeys, a value >300 EPG may be a safe recommendation. We have highlighted the main points of the discussion including the dynamics of helminth infections between the 2 species.

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“…Three classes of anthelmintic are authorised for the treatment of cyathostomin infections in the UK: the benzimidazoles (fenbendazole), the tetrahydropyrimidines (pyrantel salts) and the macrocyclic lactones (ivermectin and moxidectin). Resistance among the cyathostomins to the benzimidazole and tetrahydropyrimidine drugs is now widespread across the world (Kaplan et al, 2004; Lester et al, 2013; Matthews, 2014; Peregrine et al, 2014), and there is recent evidence to suggest growing resistance to the macrocyclic lactones (Abbas et al, 2021; Flores et al, 2020; Nielsen, 2022; Nielsen et al, 2018, 2020; Nielsen, Littman, et al, 2022; Relf et al, 2014), including in the UK (Bull et al, 2023). However, reports suggest that, in most regions, the macrocyclic lactones continue to have considerably higher observed anthelmintic efficacy against strongyle infections than the other two drug classes (Nielsen et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Strongyle egg reappearance periods following moxidectin treatment in horses in Southeast England

Mair

Opie

Moreton-Clack

et al. 2023

Equine Veterinary Education

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BackgroundA reduction in the egg reappearance period (ERP) has been suggested to be an early indication of emerging anthelmintic resistance in strongyles.ObjectiveTo measure the strongyle ERP following moxidectin treatment of horses in the southeast of England.Study designProspective study.MethodsHorses with a faecal egg count (FEC) of ≥400 strongyle eggs per gram (EPG) in a routine screening sample were enrolled into the study. Moxidectin (400 μg/kg) was administered per os and FEC tests repeated every 2 weeks for 16 weeks.ResultsForty‐eight horses completed the study. The mean EPG prior to treatment was 1047 (range 375–2137 EPG). In all but two horses, FEC was 0 EPG 2 weeks after moxidectin administration. In the remaining two, the FECs were each 12.5 EPG (97.8%–98.3% reductions compared to pre‐treatment FEC). At 4 weeks post‐treatment, 6 horses had positive FECs (96.6%–99.2% reductions). At 6 weeks, 11 horses had positive FECs (83.8% reduction in one horse; >90% reduction in 10). At 8 weeks, 21 horses exhibited positive FECs (<90% reduction in 2). At 10 weeks, 27 horses had positive FECs (<90% in 6). At 12 weeks, 31 horses had positive FECs (<90% reduction in 11). At 14 weeks, 34 horses had positive FECs (<90% reduction in 13). At 16 weeks, 38 horses had positive FECs (<90% reduction in 17).Main limitationsWeights of some horses were estimated using weigh tapes rather than a weighbridge. Dosing of the horses with moxidectin was carried out by owners.ConclusionsThe results indicated acceptable efficacy of moxidectin at 14 days after treatment; however, the ERP pattern measured across the group suggests that this anthelmintic has a considerably shorter suppressive effect on strongyle egg shedding than measured when it was first introduced (12–16 weeks).

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Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Cited by 8 publications

References 27 publications

Anthelmintic resistance in equine nematodes: Current status and emerging trends

Anthelmintic resistance in equine nematodes: Current status and emerging trends

Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections

Strongyle egg reappearance periods following moxidectin treatment in horses in Southeast England

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