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Veterinary parasitology2014; 202(3-4); 95-103; doi: 10.1016/j.vetpar.2014.03.020

Selective therapy in equine parasite control–application and limitations.

Abstract: Since the 1960s equine parasite control has relied heavily on frequent anthelmintic treatments often applied with frequent intervals year-round. However, increasing levels of anthelmintic resistance in cyathostomins and Parascaris equorum are now forcing the equine industry to change to a more surveillance-based treatment approach to facilitate a reduction in treatment intensity. The principle of selective therapy has been implemented with success in small ruminant parasite control, and has also found use in horse populations. Typically, egg counts are performed from all individuals in the population, and those exceeding a predetermined cutoff threshold are treated. Several studies document the applicability of this method in populations of adult horses, where the overall cyathostomin egg shedding can be controlled by only treating about half the horses. However, selective therapy has not been evaluated in foals and young horses, and it remains unknown whether the principle is adequate to also provide control over other important parasites such as tapeworms, ascarids, and large strongyles. One recent study associated selective therapy with increased occurrence of Strongylus vulgaris. Studies are needed to evaluate potential health risks associated with selective therapy, and to assess to which extent development of anthelmintic resistance can be delayed with this approach. The choice of strongyle egg count cutoff value for anthelmintic treatment is currently based more on tradition than science, and a recent publication illustrated that apparently healthy horses with egg counts below 100 eggs per gram (EPG) can harbor cyathostomin burdens in the range of 100,000 luminal worms. It remains unknown whether leaving such horses untreated constitutes a potential threat to equine health. The concept of selective therapy has merit for equine strongyle control, but several questions remain as it has not been fully scientifically evaluated. There is a great need for new and improved methods for diagnosis and surveillance to supplement or replace the fecal egg counts, and equine health parameters need to be included in studies evaluating any parasite control program.
Copyright © 2014 Elsevier B.V. All rights reserved.
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Publication Date: 2014-03-22 PubMed ID: 24702770DOI: 10.1016/j.vetpar.2014.03.020Google 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 research article discusses the application and limitations of selective therapy in equine parasite control, with a focus on various equine parasites and potential health risks associated with the strategy.

Overview of the Research

  • The purpose of the study was to examine the use and boundaries of selective therapy in controlling equine parasites.
  • Selective therapy requires an assessment of parasite infestation in each horse, with only those having certain predesignated levels of infestation being given treatment.
  • The paper underlines the urgency to shift from a frequent and intense anthelmintic treatment approach to a more surveillance-based method due to the increasing resistance of certain equine parasites against anthelmintic.

Selective Therapy: Application and Success Rate

  • Since the 1960s, frequent treatment using anthelmintics has been the mainstay of equine parasite control. However, this is being reassessed due to growing levels of resistance among certain parasites.
  • Selective therapy has yielded promising results in controlling small ruminant parasites and has been implemented in horse populations.
  • About half the adult horse population needs treatment under this approach to control cyathostomin egg shedding.

Limitations of Selective Therapy

  • Selective therapy has not been evaluated in foals and young horses. Hence its effectiveness in this demographic is unknown.
  • The research highlights that it is unclear if this approach can control other pivotal parasites such as tapeworms, ascarids, and large strongyles.
  • A recent study linked selective therapy with an increased occurrence of the parasite Strongylus vulgaris, raising concerns about the potential health risks associated with this methodology.
  • The article underscores the need for further research to evaluate the health risks associated with selective therapy and to ascertain the extent to which this approach can delay the development of anthelmintic resistance.

Selecting Cutoff values and Need for Future Research

  • The selection of strongyle egg count cutoff value for anthelmintic treatment has traditionally been arbitrary and lacks scientific base.
  • A recent publication suggested that seemingly healthy horses with egg counts below 100 eggs per gram could harbor as many as 100,000 cyathostomin worms, leading to questions around whether leaving horses untreated might pose a significant risk to their health.
  • New methods for diagnosis and surveillance to supplement or replace fecal egg counts are urgently needed, and equine health parameters should be included in studies evaluating any parasite control program.

Cite This Article

APA
Nielsen MK, Pfister K, von Samson-Himmelstjerna G. (2014). Selective therapy in equine parasite control–application and limitations. Vet Parasitol, 202(3-4), 95-103. https://doi.org/10.1016/j.vetpar.2014.03.020

Publication

Veterinary parasitology
ISSN: 1873-2550
NlmUniqueID: 7602745
Country: Netherlands
Language: English
Volume: 202
Issue: 3-4
Pages: 95-103

Researcher Affiliations

Nielsen, M K
  • M.H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA. Electronic address: martin.nielsen@uky.edu.
Pfister, K
  • Department of Comparative Tropical Medicine & Parasitology, University of Munich, Munich, Germany.
von Samson-Himmelstjerna, G
  • Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.

MeSH Terms

  • Animals
  • Anthelmintics / administration & dosage
  • Anthelmintics / pharmacology
  • Drug Resistance
  • Helminthiasis, Animal / drug therapy
  • Helminths / drug effects
  • Horse Diseases / drug therapy
  • Horses
  • Parasite Egg Count / veterinary

Citations

This article has been cited 15 times.
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