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Home / Equine Research Bank / Parasitol Res / Further indication of lowered activity of ivermectin on imma...
Parasitology research2012; 112(2); 889-891; doi: 10.1007/s00436-012-3098-0

Further indication of lowered activity of ivermectin on immature small strongyles in the intestinal lumen of horses on a farm in Central Kentucky.

Abstract: Critical tests were performed in 2011 in four weanling horses (L-1, L-2, L-29, and L-30) treated with ivermectin paste at 200 μg/kg. They were born in 2011 and raised together on a farm (MC) in Central Kentucky. The horses had not been treated previously with an antiparasitic drug. However, ivermectin had been administered repeatedly to the horse herd for several years and strongyle eggs per gram of feces (EPGs) returned sooner posttreatment than after initial usage. Critical tests in a recent previous study in this horse herd indicated that the reason for the early return of strongyle EPGs after ivermectin treatment probably was because of lowered drug activity on immature (L(4)) small strongyles in the lumen of the large intestine. Therefore, the life cycle was shortened. The main purpose of the present study was to obtain further data on the activity of ivermectin on small strongyle immature stages, in addition to adults, in the intestinal lumen. Twelve species of small strongyles were present. Combined data for immature and adult small strongyles for the four ivermectin-treated horses demonstrated efficacy of 68 to 83 %. Removal of adults was 100 % for all four horses, and on immatures, it ranged from 0 to 16 %. Efficacy on immature small strongyles was even lower than in the previous study. This supported the earlier finding of apparent reduced time for maturation of the parasites because of incomplete elimination of immature small strongyles in the intestinal lumen of horses after ivermectin treatment. Data on five other helminth species were recorded.
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Publication Date: 2012-09-05 PubMed ID: 22948206DOI: 10.1007/s00436-012-3098-0Google Scholar: Lookup
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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.

The study examines the lowered effectiveness of the antiparasitic drug ivermectin on immature small strongyles (a type of parasite) in the intestinal lumen of horses in a farm in Central Kentucky. The research found that ivermectin’s efficacy ranged from 68 to 83%, with its performance on immature small strongyles being significantly lower than on adult ones.

Background of the Research

  • The research involved tests performed on four weanling horses in 2011, all of which were born the same year and raised together on a Central Kentucky farm.
  • These horses had not been treated with any antiparasitic drug prior to the research. Despite this, the herd they belonged to had been regularly administered with ivermectin for several years.
  • The researchers noted an earlier return of strongyle eggs in the horse feces after ivermectin treatment than initially observed, prompting the study.
  • A previous study had suggested that this early return of strongyle eggs was due to the lowered activity of ivermectin on immature small strongyles in the large intestine, resulting in a shortened life cycle for the parasites.

Aims and Methodology

  • The main aim of the study was to gather more data on the activity of ivermectin on the immature stages of small strongyles, in addition to the adults, in the intestinal lumen.
  • The study found twelve different species of small strongyles in the horses.
  • The data for immature and adult small strongyles in the ivermectin-treated horses were pooled and analyzed.

Research Findings

  • The research found the efficacy of ivermectin on small strongyles to range from 68 to 83%.
  • The elimination of adult small strongyles was 100 % successful in all four horses. However, on immature small strongyles, the performance ranged between 0 to 16% only.
  • The efficacy on immature small strongyles was found to be even lower than in the previous study.
  • The data supported the earlier finding that the time for maturation of parasites was reduced due to incomplete elimination of immature small strongyles after ivermectin treatment.
  • The researchers also recorded data on five other helminth species during the study.

This research emphasizes the need for improved methods of controlling parasitic infections in horses, as current treatments with ivermectin appear to be losing their effectiveness, particularly against the immature stages of small strongyles.

Cite This Article

APA
Lyons ET, Tolliver SC. (2012). Further indication of lowered activity of ivermectin on immature small strongyles in the intestinal lumen of horses on a farm in Central Kentucky. Parasitol Res, 112(2), 889-891. https://doi.org/10.1007/s00436-012-3098-0

Publication

Parasitology research
ISSN: 1432-1955
NlmUniqueID: 8703571
Country: Germany
Language: English
Volume: 112
Issue: 2
Pages: 889-891

Researcher Affiliations

Lyons, E T
  • Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY 40546-0099, USA. elyons1@uky.edu
Tolliver, S C

    MeSH Terms

    • Animals
    • Anthelmintics / therapeutic use
    • Drug Resistance
    • Feces / parasitology
    • Horses
    • Ivermectin / therapeutic use
    • Kentucky
    • Parasite Egg Count
    • Strongyle Infections, Equine / drug therapy
    • Strongyloidea / classification
    • Strongyloidea / drug effects
    • Strongyloidea / growth & development
    • Strongyloidea / isolation & purification
    • Treatment Failure

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    This article includes 8 references
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    Citations

    This article has been cited 6 times.
    1. Bull KE, Allen KJ, Hodgkinson JE, Peachey LE. The first report of macrocyclic lactone resistant cyathostomins in the UK.. Int J Parasitol Drugs Drug Resist 2023 Apr;21:125-130.
      doi: 10.1016/j.ijpddr.2023.03.001pubmed: 36940551google scholar: lookup
    2. Macdonald SL, Abbas G, Ghafar A, Gauci CG, Bauquier J, El-Hage C, Tennent-Brown B, Wilkes EJA, Beasley A, Jacobson C, Cudmore L, Carrigan P, Hurley J, Beveridge I, Hughes KJ, Nielsen MK, Jabbar A. Egg reappearance periods of anthelmintics against equine cyathostomins: The state of play revisited.. Int J Parasitol Drugs Drug Resist 2023 Apr;21:28-39.
      doi: 10.1016/j.ijpddr.2022.12.002pubmed: 36543048google scholar: lookup
    3. 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).
      doi: 10.3390/ani10122283pubmed: 33287298google scholar: lookup
    4. Nielsen MK, Banahan M, Kaplan RM. Importation of macrocyclic lactone resistant cyathostomins on a US thoroughbred farm.. Int J Parasitol Drugs Drug Resist 2020 Dec;14:99-104.
      doi: 10.1016/j.ijpddr.2020.09.004pubmed: 33022574google scholar: lookup
    5. Matthews JB. Anthelmintic resistance in equine nematodes.. Int J Parasitol Drugs Drug Resist 2014 Dec;4(3):310-5.
      doi: 10.1016/j.ijpddr.2014.10.003pubmed: 25516842google scholar: lookup
    6. Schneider S, Pfister K, Becher AM, Scheuerle MC. Strongyle infections and parasitic control strategies in German horses - a risk assessment.. BMC Vet Res 2014 Nov 12;10:262.
      doi: 10.1186/s12917-014-0262-zpubmed: 25387542google scholar: lookup
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