Effect of early season ivermectin and pyrantel treatments on strongylid infections in young Shetland ponies in The Netherlands.
Abstract: Two groups of three ponies were used to study the effect of three ivermectin or pyrantel treatments given at intervals of 5 weeks at the beginning of the grazing season. Although each pyrantel treatment resulted in a greater than 95% reduction in faecal egg counts during the first 3 weeks, high pasture larval counts were seen from the beginning of August onwards and substantial cyathostomine burdens were found at necropsy in December. The ivermectin treatments resulted in an even more pronounced reduction in faecal egg output, and the pasture larval counts and cyathostomine burdens at necropsy were considerably lower than in the pyrantel group. The proportion of inhibited early L3 of the cyathostomines was lower in the ivermectin than in the pyrantel group. Faecal egg output of the large strongyles was completely suppressed in the ivermectin group. Nevertheless, Strongylus vulgaris larvae were found in the arteries of all three ponies, possibly as a result of overwintering of infective larvae on pasture. In the pyrantel group, the egg output of Strongylus edentatus and, to a much lesser extent, Strongylus vulgaris, was not completely suppressed.
Publication Date: 1991-01-01 PubMed ID: 2024428DOI: 10.1016/0304-4017(91)90005-gGoogle Scholar: Lookup
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Summary
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This research article investigates the effectiveness of using ivermectin or pyrantel, two types of deworming drugs, on young Shetland ponies in the Netherlands to treat strongylid infections, which are types of intestinal parasitic worms. The study found that ivermectin was more potent than pyrantel in reducing both egg output in feces and the worms’ burdens at the end of the study. However, one type of worm, Strongylus vulgaris, was found in all test subjects despite the treatments, suggesting that some worms may be resistant or that the larvae may survive colder weather on pastures.
Study Design
- The researchers used two groups of three Shetland ponies each to test the effectiveness of the treatments.
- Each group was treated with either ivermectin or pyrantel three times at five week intervals at the start of the grazing season.
Results of Pyrantel Treatment
- Each pyrantel treatment led to a reduction of more than 95% in fecal egg counts for the initial three weeks.
- However, high counts of larvae were seen in pastures from the start of August onwards, and the ponies had significant cyathostomine (a type of small strongyle) burdens as determined at necropsy (a post-mortem examination) in December.
Results of Ivermectin Treatment
- The ivermectin treatments provided a more significant reduction in fecal egg output.
- The pasture larval counts and cyathostomine burdens at necropsy were considerably lower in the ivermectin-treated group compared to the pyrantel-treated group.
- The proportion of early L3 (larval stage 3) cyathostomines that were inhibited or ‘stunned’ was lower in the ivermectin group compared to the pyrantel group.
- Fecal egg output of large strongyles (a type of intestinal worm) was completely suppressed in the ivermectin group.
Possible Resistance
- Despite the successful treatment, Strongylus vulgaris larvae were found in all treated ponies in both groups, suggesting possible resistance to the deworming drugs or the capability of the larvae to survive over winter on the pasture.
- In the pyrantel group, egg output from Strongylus edentatus and to a lesser degree Strongylus vulgaris, were not completely suppressed, indicating that pyrantel might not be fully effective against these worms.
Cite This Article
APA
Eysker M, Boersema JH, Kooyman FN.
(1991).
Effect of early season ivermectin and pyrantel treatments on strongylid infections in young Shetland ponies in The Netherlands.
Vet Parasitol, 38(1), 33-39.
https://doi.org/10.1016/0304-4017(91)90005-g Publication
Researcher Affiliations
- Department of Infectious Diseases and Immunology, University of Utrecht, The Netherlands.
MeSH Terms
- Animals
- Feces / parasitology
- Female
- Horses
- Ivermectin / therapeutic use
- Netherlands
- Parasite Egg Count / veterinary
- Pyrantel / therapeutic use
- Random Allocation
- Seasons
- Strongyle Infections, Equine / prevention & control
Citations
This article has been cited 3 times.- Lyons ET, Tolliver SC. 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 2013 Feb;112(2):889-91.
- Lyons ET, Tolliver SC, Collins SS. Probable reason why small strongyle EPG counts are returning "early" after ivermectin treatment of horses on a farm in Central Kentucky.. Parasitol Res 2009 Feb;104(3):569-74.
- Ihler CF. A field survey on anthelmintic resistance in equine small strongyles in Norway.. Acta Vet Scand 1995;36(1):135-43.
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