An investigation of anthelmintic efficacy against strongyles on equine yards in Scotland.
Abstract: Cyathostomins comprise 50 helminth species, considered the most problematic equine endoparasites. Three classes of anthelmintic are currently licensed for their control, namely the benzimidazoles (fenbendazole), tetrahydropyrimidines (pyrantel) and macrocyclic lactones (ivermectin and moxidectin). Anthelmintic resistance in cyathostomins is common. With no new classes expected in the near future, it is essential to determine the efficacy of the available anthelmintics to inform future control programmes. Objective: To determine the efficacy of all 3 anthelmintic classes against strongyles in equids on livery yards in east and central Scotland. Methods: Anthelmintic efficacy testing using the faecal egg count reduction test (FECRT). Methods: FECRTs were performed on equids with initial strongyle faecal egg counts (FECs) of ≥50 eggs per gram. Efficacy was determined by comparing pretreatment (Day 0) and 14 days post treatment (Day 14) FECs. The following chemicals were tested: fenbendazole, pyrantel, ivermectin and moxidectin. Group arithmetic mean FECR of >90% for fenbendazole and pyrantel, and >95% for ivermectin and moxidectin, represented efficacy, whereas lower mean FECR indicated potential resistance. Results: A total of 447 FECRTs were performed on 15 yards, as follows (the numbers in parentheses represent the number of yards each anthelmintic was tested on): 55 equids (7 yards) fenbendazole, 111 (8 yards) pyrantel, 163 (13 yards) ivermectin and 118 (10 yards) moxidectin. Fenbendazole resistance was documented on all yards (range of mean FECR, 15.8-83.4%), whereas pyrantel (90.4-99.6%), ivermectin (99.5-100%) and moxidectin (99.4-100%) treatment had acceptable efficacy. Conclusions: Reduced efficacy of fenbendazole was widespread, whereas >90% efficacy was found after pyrantel, and >95% efficacy after ivermectin and moxidectin. Overall, efficacies were higher than reported previously in Europe and the USA, potentially reflecting differences in management and anthelmintic use on the yards surveyed. Conclusions: The use of fenbendazole for strongyle control in Scotland should be questioned. Targeted use of pyrantel should be encouraged to reduce reliance on macrocyclic lactones. Further work to correlate management practices with the presence of anthelmintic resistance is warranted.
© 2013 EVJ Ltd.
Publication Date: 2013-05-15 PubMed ID: 23662803DOI: 10.1111/evj.12079Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article investigates the effectiveness of three classes of anthelmintic drugs (medicines that expel parasites) against equine endoparasites (internal parasites) in Scotland. Key available drugs were tested and their efficacy was determined by comparing stool sample egg counts before and after treatment. It found that one of the medicines, fenbendazole, was not effective, while the other two classes showed high efficacy.
Objective of the Research
- The core objective of the research was to determine how well each of the three primary classes of anthelmintic drugs (fenbendazole, pyrantel, ivermectin and moxidectin) perform against strongyles (a group of 50 problematic equine endoparasites) on livery yards in east and central Scotland.
Methodology and Results
- The researchers used a faecal egg count reduction test (FECRT) as the method for ascertaining the effectiveness of the drugs. For an animal to be eligible for testing, their initial faecal egg count had to be 50 eggs per gram or higher.
- To evaluate the efficacy, pre-treatment fecal egg counts were compared with the counts 14 days post treatment. An effectiveness greater than 90% for fenbendazole and pyrantel, and over 95% for ivermectin and moxidectin was considered significant. Lower mean FECR indicated possible resistance.
- Fenbendazole was tested on 55 horses from 7 yards, pyrantel on 111 horses from 8 yards, ivermectin on 163 horses from 13 yards, and moxidectin on 118 horses from 10 yards. In total, 447 FECRTs were carried out on 15 yards.
- The efficacy of fenbendazole was found to be low on all yards resulting in evidence of resistance. On the other hand, pyrantel, ivermectin and moxidectin showed acceptable efficacy levels.
Conclusions and Recommendations
- The low efficacy of fenbendazole suggests that its use for strongyle control in Scotland is questionable as there’s widespread resistance.
- The study recommended targeted use of pyrantel to reduce reliance on macrocyclic lactones (ivermectin and moxidectin).
- The authors concluded that further research is required to correlate management practices with the presence of anthelmintic resistance.
- Overall, efficacies were higher than previously reported in Europe and the USA, possibly due to differences in management practices and anthelmintic use.
Cite This Article
APA
Stratford CH, Lester HE, Pickles KJ, McGorum BC, Matthews JB.
(2013).
An investigation of anthelmintic efficacy against strongyles on equine yards in Scotland.
Equine Vet J, 46(1), 17-24.
https://doi.org/10.1111/evj.12079 Publication
Researcher Affiliations
- Royal (Dick) School of Veterinary Studies and Roslin Institute, University of Edinburgh, UK.
MeSH Terms
- Animals
- Anthelmintics / pharmacology
- Drug Resistance
- Feces / parasitology
- Helminths / drug effects
- Horse Diseases / drug therapy
- Horse Diseases / epidemiology
- Horse Diseases / parasitology
- Horses
- Parasite Egg Count
- Scotland / epidemiology
Citations
This article has been cited 12 times.- Elghryani N, Lawlor A, McOwan T, de Waal T. Unravelling the Effectiveness of Anthelmintic Treatments on Equine Strongyles on Irish Farms. Animals (Basel) 2024 Jul 2;14(13).
- Nielsen MK. Anthelmintic resistance in equine nematodes: Current status and emerging trends. Int J Parasitol Drugs Drug Resist 2022 Dec;20:76-88.
- Dauparaitė E, Kupčinskas T, Varady M, Petkevičius S. Anthelmintic resistance of horse strongyle nematodes to fenbendazole in Lithuania. Acta Vet Scand 2022 Sep 15;64(1):26.
- Mathewos M, Teshome D, Fesseha H. Study on Gastrointestinal Nematodes of Equines in and around Bekoji, South Eastern Ethiopia. J Parasitol Res 2022;2022:8210160.
- Nápravníková J, Várady M, Vadlejch J. Total Failure of Fenbendazole to Control Strongylid Infections in Czech Horse Operations. Front Vet Sci 2022;9:833204.
- Scala A, Tamponi C, Sanna G, Predieri G, Dessì G, Sedda G, Buono F, Cappai MG, Veneziano V, Varcasia A. Gastrointestinal Strongyles Egg Excretion in Relation to Age, Gender, and Management of Horses in Italy. Animals (Basel) 2020 Dec 3;10(12).
- Mitchell CJ, O'Sullivan CM, Pinloche E, Wilkinson T, Morphew RM, McEwan NR. Using next-generation sequencing to determine diversity of horse intestinal worms: identifying the equine 'nemabiome'. J Equine Sci 2019 Mar;30(1):1-5.
- Palomero AM, Hernández JA, Cazapal-Monteiro CF, Balán FA, Silva MI, Paz-Silva A, Sánchez-Andrade R, Vázquez MSA. Implementation of Biological Control to the Integrated Control of Strongyle Infection among Wild Captive Equids in a Zoological Park. Biomed Res Int 2018;2018:4267683.
- Molena RA, Peachey LE, Di Cesare A, Traversa D, Cantacessi C. Cyathostomine egg reappearance period following ivermectin treatment in a cohort of UK Thoroughbreds. Parasit Vectors 2018 Jan 25;11(1):61.
- Zak A, Siwinska N, Slowikowska M, Borowicz H, Kubiak K, Hildebrand J, Popiolek M, Niedzwiedz A. Searching for ivermectin resistance in a Strongylidae population of horses stabled in Poland. BMC Vet Res 2017 Jul 3;13(1):210.
- Love S, Burden FA, McGirr EC, Gordon L, Denwood MJ. Equine Cyathostominae can develop to infective third-stage larvae on straw bedding. Parasit Vectors 2016 Aug 31;9(1):478.
- Matthews JB. Anthelmintic resistance in equine nematodes. Int J Parasitol Drugs Drug Resist 2014 Dec;4(3):310-5.
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