Reduced activity of moxidectin and ivermectin on small strongyles in young horses on a farm (BC) in Central Kentucky in two field tests with notes on variable counts of eggs per gram of feces (EPGs).
Abstract: Two field tests (A and B) were conducted in Thoroughbred weanlings born in 2008 and 2009 on a farm (BC) in Central Kentucky. The purpose was to determine the current efficacy of moxidectin (MOX) and ivermectin (IVM) on small strongyles by pre- and posttreatment counts of eggs per gram of feces (EPGs) in this geographical area. In previous parasite studies in horses on this farm and in horses on numerous other farms in this area, cultures of feces indicated the strongyle larvae were all small strongyles. Therefore, the strongyle eggs in the EPG counts are considered small strongyles. Designation of the location of the horses in the current study is by barn number. However, the horses were kept on pastures except when gotten up in the specific barns for treatment and collection of feces. The number of horses for study A (2008-2009) was 40 in a total of ten barns (four in each location) and that for study B (2009-2010) was 49 in a total of nine barns (four each in six locations and seven to nine each in three locations). The nine barns for the study-B horses were the same ones used for the study-A horses; the tenth barn for study A was not used for study B. The number of horses treated was 20 with MOX and 20 with IVM in study A and 24 with MOX and 25 with IVM in study B. Drugs given to horses in barns in study B were switched from those used in barns in study A. That is, horses in barns where MOX was used in study A were given IVM and vice versa for those in study B. Study-A horses in some of the barns had unexplained either negative or delayed return of EPG counts after treatment with either drug, compared to horses in other barns. No reason for inconsistencies could be determined. Study B was initiated to compare results with study-A horses, relative to their location in the same barns. Study- B horses, contrary to horses in study A, had mostly consistent results between barns. Most of the MOX- and IVM-treated horses in study B and some in study A had strongyle EPG counts returning almost twice as quickly as when these compounds were first marketed.
Publication Date: 2011-01-07 PubMed ID: 21212983DOI: 10.1007/s00436-010-2225-zGoogle Scholar: Lookup
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- Journal Article
Summary
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The research article presents the findings of two field studies conducted on Thoroughbred weanlings in Central Kentucky to evaluate the effectiveness of antiparasitic drugs, moxidectin (MOX) and ivermectin (IVM), against small strongyles, a type of equine parasite, by measuring pre- and posttreatment levels of strongyle eggs in horse feces.
Study Design
- The two studies were carried out on a farm, denoted as BC, in Central Kentucky.
- The studies involved young horses born in 2008 and 2009, and the horses were primarily kept on pastures.
- The primary method of evaluation was to count the amount of strongyle eggs per gram of feces (EPGs) before and after the application of the drugs.
- Study A involved 40 horses housed in 10 barns, with 20 each treated with MOX and IVM. Study B included 49 horses in 9 barns, with 24 and 25 horses treated with MOX and IVM, respectively.
- In the second study, the drugs given to the horses were switched from the ones used in the initial study.
Findings
- Comparison of pre- and posttreatment EPG counts was used to determine drug efficacy.
- Findings from study A showed inconsistent results, with unexplained variances in EPG count recovery in horses from different barns following drug treatment.
- Study B, however, showed mostly consistent results between barns, providing a clearer picture of drug efficacy.
- Both studies showed that post-treatment strongyle EPG counts returned almost twice as quickly for most of the MOX and IVM treated horses as when these drugs were first introduced to the market.
Conclusion
- The study suggests a decreased efficacy of MOX and IVM in treating small strongyles in young horses, indicating potential resistance or tolerance to these drugs among the strongyles.
- Continued monitoring and further studies are warranted to confirm these findings and explore alternative treatment methods.
Cite This Article
APA
Lyons ET, Tolliver SC, Collins SS.
(2011).
Reduced activity of moxidectin and ivermectin on small strongyles in young horses on a farm (BC) in Central Kentucky in two field tests with notes on variable counts of eggs per gram of feces (EPGs).
Parasitol Res, 108(5), 1315-1319.
https://doi.org/10.1007/s00436-010-2225-z Publication
Researcher Affiliations
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546-0099, USA. elyons1@uky.edu
MeSH Terms
- Animals
- Anthelmintics / administration & dosage
- Feces / parasitology
- Horse Diseases / drug therapy
- Horse Diseases / parasitology
- Horses
- Ivermectin / administration & dosage
- Kentucky
- Macrolides / administration & dosage
- Parasite Egg Count
- Strongylida / isolation & purification
- Strongylida Infections / drug therapy
- Strongylida Infections / parasitology
- Treatment Outcome
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This article includes 10 references
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Citations
This article has been cited 5 times.- Malsa J, Courtot É, Boisseau M, Dumont B, Gombault P, Kuzmina TA, Basiaga M, Lluch J, Annonay G, Dhorne-Pollet S, Mach N, Sutra JF, Wimel L, Dubois C, Guégnard F, Serreau D, Lespine A, Sallé G, Fleurance G. Effect of sainfoin (Onobrychis viciifolia) on cyathostomin eggs excretion, larval development, larval community structure and efficacy of ivermectin treatment in horses.. Parasitology 2022 Sep;149(11):1439-1449.
- Walshe N, Mulcahy G, Crispie F, Cabrera-Rubio R, Cotter P, Jahns H, Duggan V. Outbreak of acute larval cyathostominosis - A "perfect storm" of inflammation and dysbiosis.. Equine Vet J 2021 Jul;53(4):727-739.
- Sanna G, Pipia AP, Tamponi C, Manca R, Varcasia A, Traversa D, Scala A. Anthelmintics efficacy against intestinal strongyles in horses of Sardinia, Italy.. Parasite Epidemiol Control 2016 Jun;1(2):15-19.
- 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.
- Lyons ET, Tolliver SC, Kuzmina TA. Investigation of strongyle EPG values in horse mares relative to known age, number positive, and level of egg shedding in field studies on 26 farms in Central Kentucky (2010-2011).. Parasitol Res 2012 Jun;110(6):2237-45.
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