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Home / Equine Research Bank / Acta Vet Scand / A field survey on anthelmintic resistance in equine small st...
Acta veterinaria Scandinavica1995; 36(1); 135-143; doi: 10.1186/BF03547710

A field survey on anthelmintic resistance in equine small strongyles in Norway.

Abstract: A field survey at 17 stables involving 221 horses was performed to evaluate the presence of anthelmintic resistance in the equine small strongyles (cyathostomes). The horses were allocated into treatment groups, and resistance to fenbendazole (FBZ), pyrantel pamoate (PYR) and ivermectin (IVM) was tested by the faecal egg count reduction test (FECR-test). Faecal samples were collected at the time of treatment, 14 days post treatment and 90 days post treatment. Resistance to FBZ, which was defined as a faecal egg count reduction < 95%, was found in 14 out of 17 stables. In 2 of the 14 stables the egg reductions were close to the limit of 95%, 91 and 93%, respectively. In 1 stable the egg reductions indicated resistance to PYR as well as detection of resistance to FBZ, 94% reduction for PYR and 85% for FBZ. No signs of resistance were detected to IVM. The investigation was performed in late autumn and winter, and due to the climatic conditions and cleaning procedures in the stables no reinfection took place during this period. The faecal egg count reduction from treatment till day 90 post treatment was used as an expression of the effect of PYR and IVM on the early stage (hypobiotic), late third stage and fourth stage larvae in the gut wall. This was justified because there was no reinfection and because the 14 day post treatment egg counts were zero or close to zero for the PYR and IVM treatment groups. The effects of PYR and IVM on the larval stages were compared and no statistically significant differences were found.
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Publication Date: 1995-01-01 PubMed ID: 7572451PubMed Central: PMC8095490DOI: 10.1186/BF03547710Google Scholar: Lookup
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  • Clinical Trial
  • Journal Article
  • Randomized Controlled Trial
  • Research Support
  • Non-U.S. Gov't

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.

The research article discusses a field survey conducted in Norway that investigated the presence of anthelmintic resistance in equine small strongyles (a type of horse parasite) against three specific drugs. The study found resistance to two of the drugs but none to the third.

Field Survey Details

  • The survey was administered in 17 stables with a total of 221 horses. The goal was to evaluate the level of resistance small strongyles — a common type of horse parasite — had developed against three anthelmintic drugs: fenbendazole (FBZ), pyrantel pamoate (PYR) and ivermectin (IVM).
  • Horses were assigned to treatment groups, and resistance to the drugs was tested through the faecal egg count reduction test (FECR-test), with samples collected at the time of treatment, 14 days post treatment and 90 days post treatment.

Anthelmintic Resistance Results

  • The study found resistance to fenbendazole (FBZ) in 14 out of the 17 stables; resistance was classified as an egg count reduction of less than 95%. However, in two of the 14 stables, egg reduction rates were close to the 95% threshold, measuring 91% and 93%.
  • In one of the stables, a resistance to both FBZ and pyrantel pamoate (PYR) was detected. The egg reduction was 94% for PYR and 85% for FBZ.
  • The research indicated no resistance to ivermectin (IVM).

Investigation Period and Conditions

  • The survey was carried out during late autumn and winter. Due to the climatic conditions and stable cleaning procedures, no reinfections occurred during the investigation period.
  • The faecal egg count reduction from treatment to 90 days post treatment was used as a measure of PYR and IVM effect on early-stage, late third-stage, and fourth-stage larvae in the gut wall. Since no reinfection occurred and because the 14-day post-treatment egg counts were zero or near zero for the PYR and IVM treatment groups, this measure accurately depicted drug efficacy.

Drug Effect Comparisons

  • The study compared the effects of PYR and IVM on the larvae at different stages. No significant statistical differences were found between the two drugs in terms of their abilities to treat the larvae.

Cite This Article

APA
Ihler CF. (1995). A field survey on anthelmintic resistance in equine small strongyles in Norway. Acta Vet Scand, 36(1), 135-143. https://doi.org/10.1186/BF03547710

Publication

Acta veterinaria Scandinavica
ISSN: 0044-605X
NlmUniqueID: 0370400
Country: England
Language: English
Volume: 36
Issue: 1
Pages: 135-143

Researcher Affiliations

Ihler, C F
  • Department of Large Animal Sciences, Norwegian College of Veterinary Medicine, Oslo.

MeSH Terms

  • Animals
  • Antinematodal Agents / therapeutic use
  • Drug Resistance
  • Fenbendazole / therapeutic use
  • Horse Diseases / drug therapy
  • Horse Diseases / parasitology
  • Horses
  • Ivermectin / therapeutic use
  • Norway
  • Parasite Egg Count / veterinary
  • Pyrantel / therapeutic use
  • Strongyle Infections, Equine / drug therapy
  • Strongylus / drug effects

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Citations

This article has been cited 8 times.
  1. Jamshidpour R, Nabavi R, Moadab H, Rezaie F, Chale AC, Sargison N. Evaluation of Benzimidazole Resistance in Equine Cyathostomins in the Kermanshah Province of Iran Using Coprological Analysis and Allele-Specific PCR. Iran J Parasitol 2025 Jul-Sep;20(3):389-399.
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  2. Cabaret J. Independent Development of Resistance to Main Classes of Anthelmintics by Gastrointestinal Nematodes of Ruminants and Horses. Pathogens 2025 Sep 5;14(9).
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  3. 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.
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  4. Zanet S, Battisti E, Labate F, Oberto F, Ferroglio E. Reduced Efficacy of Fenbendazole and Pyrantel Pamoate Treatments against Intestinal Nematodes of Stud and Performance Horses. Vet Sci 2021 Mar 5;8(3).
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