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The Canadian veterinary journal = La revue veterinaire canadienne2008; 49(1); 56-60;

The persistence of benzimidazole-resistant cyathostomes on horse farms in Ontario over 10 years and the effectiveness of ivermectin and moxidectin against these resistant strains.

Abstract: Three clinical trials with fecal egg count reduction tests and coproculture were conducted on 2 standardbred farms in Ontario. On Farm A, the treatment groups were mebendazole and ivermectin in trial 1, and fenbendazole and moxidectin in another. On Farm B, treatment groups were mebendazole and ivermectin. All horses treated with mebendazole or fenbendazole were subsequently treated with ivermectin or moxidectin. Strongyle eggs/g feces were estimated pre- and post-treatment using the Cornell-McMaster dilution and Cornell-Wisconsin centrifugal flotation techniques. After treatment, there was no change in the arithmetic mean eggs/g feces for horses given mebendazole, and a reduction of only 49.1% for those given fenbendazole. All horses receiving ivermectin or moxidectin had their egg counts reduced to 0. Only cyathostomes were found on culture. On both farms the benzimidazole resistant strains appeared to have persisted for at least 10 years. Development of and monitoring for anthelmintic resistance are briefly discussed. Trois essais cliniques comportant des tests de réduction d’excrétion fécale d’œufs et de coproculture ont été menés dans 2 fermes de Standardbred de l’Ontario. Sur la ferme A, on retrouvait les groupes de traitement mébendazole et ivermectine dans l’essai 1 et les groupes fenbendazole et moxidectine dans l’essai 2. Sur la ferme B, les groupes de traitement étaient mébendazole et ivermectine. Tous les chevaux traités au mébendazole ou au fenbendazole ont été traités subséquemment à l’ivermectine ou à la moxidectine. Les œufs de strongles/g de fèces ont été estimés avant et après traitement par les techniques Cornell-McMaster de dilution et Cornell-Wisconsin de flottaison par centrifugation. Après traitement, il n’y avait pas de modification dans la moyenne arithmétique du nombre d’œufs/g de fèces chez les chevaux ayant reçu du mébendazole et une réduction d’à peine 49,1 % pour ceux ayant reçu du fenbendazole. Tous les chevaux ayant reçu de l’ivermectine ou de la moxidectine ont vu les comptes d’œufs réduits à 0. Seul des cyathostomes ont été retrouvés dans les cultures. Dans les 2 fermes, les souches résistantes aux benzimidazoles semblaient avoir persisté pendant au moins 10 ans. L’apparition et la surveillance de la résistance aux anthelminthiques sont brièvement présentées. (Traduit par Docteur André Blouin)
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Publication Date: 2008-03-07 PubMed ID: 18320979PubMed Central: PMC2147695
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article investigates the continuous presence of benzimidazole-resistant cyathostomes, a type of parasite, on two horse farms in Ontario over a decade. The study looks into the effectiveness of ivermectin and moxidectin, two types of anti-parasitic drugs, against these resistant parasites.

Methodology and Experiment Design

  • Three different clinical trials were carried out on two standardbred horse farms in Ontario. The trials incorporated fecal egg count reduction tests and coproculture to monitor the presence and resistance of the parasites.
  • Different groups of horses were treated with different anti-parasitic drugs: mebendazole and ivermectin in the first trial; fenbendazole and moxidectin in the second trial. Horses that initially received mebendazole or fenbendazole were subsequently treated with ivermectin or moxidectin.
  • Strongyle eggs per gram of feces were estimated before and after the treatments using the Cornell-McMaster dilution and Cornell-Wisconsin centrifugal flotation techniques. These methods allowed to determine the level of infestation in the horses and the efficacy of the drugs.

Results of the Study

  • For the group of horses that were given mebendazole, no change in the average number of eggs per gram of feces was observed after treatment.
  • In the group treated with fenbendazole, a reduction of just 49.1% in the egg count was reported.
  • Conversely, all horses that were treated with either ivermectin or moxidectin had their egg counts reduced to zero, indicating an effective result.
  • Only cyathostomes, a type of parasitic worm, were identified in the culture tests.

Interpretation and Discussion

  • Based on the results, it was demonstrated that the particular strains of cyathostomes exhibited resistance to the benzimidazole-based treatments, mebendazole and fenbendazole in particular.
  • The persistence of these resistant strains was detected for a period of at least 10 years across both tested farms.
  • The study briefly discusses the development and the need for monitoring anti-parasitic resistance as an important consideration for veterinary medicine and animal husbandry. It poses a significant concern for maintaining animal health and wellbeing, especially in settings like horse farms where such parasites can have a drastic impact on the population.

Cite This Article

APA
Slocombe JO, Coté JF, de Gannes RV. (2008). The persistence of benzimidazole-resistant cyathostomes on horse farms in Ontario over 10 years and the effectiveness of ivermectin and moxidectin against these resistant strains. Can Vet J, 49(1), 56-60.

Publication

The Canadian veterinary journal = La revue veterinaire canadienne
ISSN: 0008-5286
NlmUniqueID: 0004653
Country: Canada
Language: English
Volume: 49
Issue: 1
Pages: 56-60

Researcher Affiliations

Slocombe, J Owen D
  • Ontario Veterinary College, Department of Pathobiology, University of Guelph. oslocomb@uoguelph.ca
Coté, John F
    de Gannes, Rolph V G

      MeSH Terms

      • Animals
      • Anthelmintics / therapeutic use
      • Benzimidazoles / therapeutic use
      • Drug Resistance
      • Feces / parasitology
      • Female
      • Horse Diseases / drug therapy
      • Horses
      • Ivermectin / therapeutic use
      • Macrolides / therapeutic use
      • Male
      • Ontario
      • Parasite Egg Count / veterinary
      • Parasitic Sensitivity Tests / veterinary
      • Random Allocation
      • Strongylida Infections / drug therapy
      • Strongylida Infections / veterinary
      • Strongyloidea / drug effects
      • Treatment Outcome

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      Citations

      This article has been cited 4 times.
      1. Misuno E, Clark CR, Anderson SL, Jenkins E, Wagner B, Dembek K, Petrie L. Characteristics of parasitic egg shedding over a 1-year period in foals and their dams in 2 farms in central Saskatchewan. Can Vet J 2018 Mar;59(3):284-292.
        pubmed: 29599559
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        doi: 10.18502/ijpa.v20i3.19614pubmed: 41181201google scholar: lookup
      4. Nielsen MK. Anthelmintic resistance in equine nematodes: Current status and emerging trends. Int J Parasitol Drugs Drug Resist 2022 Dec;20:76-88.
        doi: 10.1016/j.ijpddr.2022.10.005pubmed: 36342004google scholar: lookup
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