Efficacy of pyrantel pamoate against a macrocyclic lactone-resistant isolate of Parascaris equorum in horses.
Abstract: The expanding prevalence of Parascaris equorum populations that are resistant to macrocyclic lactone (ML) anthelmintics makes it desirable to identify dewormers which remain effective. The objective was to evaluate the efficacy of pyrantel pamoate in 14 suckling foals that had been infected orally with approximately 600 larvated eggs of a P. equorum isolate selected for ML resistance (ML-R). Seventy days after inoculation, foals were weaned, housed individually, and fecal samples were examined frequently to detect the onset of patency. Between 73 and 80 days post-inoculation, all 14 foals developed P. equorum egg counts>or=150 eggs per gram (EPG). An initial cohort of eight foals was treated orally with ivermectin paste (200 microg/kg) 84-91 days post-inoculation. Egg counts were reduced by only 47% at 2 weeks after ivermectin treatment, confirming the ML-R status of the isolate. A second cohort of six foals was not treated with ivermectin. Within each cohort, eligible foals were allocated randomly to treated (pyrantel pamoate; n=7) or untreated control (n=7) groups. Treated foals were dosed orally on Day 0 with a paste formulation of pyrantel pamoate at 13.2mg/kg. Mean ascarid egg counts of treated foals were reduced by 96.0% and 98.8% at 1 and 2 weeks post-treatment, respectively. On Day 14, foals were euthanatized and specimens of P. equorum were recovered from the gut contents, preserved in 10% formalin, and counted. Mean numbers of P. equorum adults recovered postmortem were significantly lower (P=0.0031) in foals treated with pyrantel pamoate (X=1.7; range 0-16) compared to control foals (X=63.0; range 0-320). A paste formulation of pyrantel pamoate, at a dosage of 13.2 mg/kg, was 97.3% effective against a ML-R isolate of P. equorum.
Copyright (c) 2010 Elsevier B.V. All rights reserved.
Publication Date: 2010-03-04 PubMed ID: 20307936DOI: 10.1016/j.vetpar.2010.02.041Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article investigates the effectiveness of the dewormer pyrantel pamoate on a strain of horse worms (Parascaris equorum) that has developed resistance to common dewormers. The results show that pyrantel pamoate was highly effective in reducing worm egg counts and adult worm numbers.
Objective of the Study
- This study was conducted to test the effectiveness of pyrantel pamoate, a deworming medication, on a strain of horse roundworm (Parascaris equorum) that has become resistant to a common class of wormers known as macrocyclic lactone anthelmintics.
Methodology and Samples
- 14 foals that had been orally infected with approximately 600 larvae of the resistant P. equorum strain were used in the study.
- 73 to 80 days after infection, all 14 foals had a significant number of worm eggs in their feces, confirming the presence of the worms.
- An initial group of 8 foals were treated with ivermectin, another commonly used wormer, as a control test. This confirmed the worms’ resistance, as it resulted in only a 47% reduction in worm egg counts.
- Another group of 6 foals was not treated with any drug.
- Both groups were then divided into two further groups – one treated with pyrantel and one untreated, serving as a control.
Treatment and Results
- The treatment used was a paste formulation of pyrantel pamoate at a dose of 13.2mg/kg.
- 1 and 2 weeks post-treatment, the horse worm egg count in the treated foals’ feces was reduced by 96.0% and 98.8% respectively, demonstrating significant effectiveness.
- On the 14th day, the foals were put down and adult worm numbers were examined. The treated foals showed significantly lower numbers than the control foals.
- The results highlighted that pyrantel pamoate was able to effectively combat the worm’s resistance, reducing both egg counts and adult worm numbers by over 97%.
This research underscores the potential of pyrantel pamoate as an effective deworming treatment to be used against macrocyclic lactone-resistant strains of P. equorum in horses.
Cite This Article
APA
Reinemeyer CR, Prado JC, Nichols EC, Marchiondo AA.
(2010).
Efficacy of pyrantel pamoate against a macrocyclic lactone-resistant isolate of Parascaris equorum in horses.
Vet Parasitol, 171(1-2), 111-115.
https://doi.org/10.1016/j.vetpar.2010.02.041 Publication
Researcher Affiliations
- East Tennessee Clinical Research, Inc., 80 Copper Ridge Farm Road, Rockwood, TN 37854, United States. crr@easttenncr.com
MeSH Terms
- Animals
- Animals, Suckling
- Anthelmintics / administration & dosage
- Anthelmintics / standards
- Anthelmintics / therapeutic use
- Ascaridida Infections / drug therapy
- Ascaridida Infections / parasitology
- Ascaridida Infections / veterinary
- Ascaridoidea / growth & development
- Cohort Studies
- Drug Resistance
- Feces / parasitology
- Female
- Gastrointestinal Diseases / drug therapy
- Gastrointestinal Diseases / parasitology
- Horse Diseases / drug therapy
- Horse Diseases / parasitology
- Horses
- Least-Squares Analysis
- Male
- Parasite Egg Count / veterinary
- Pyrantel Pamoate / administration & dosage
- Pyrantel Pamoate / standards
- Pyrantel Pamoate / therapeutic use
- Random Allocation
Citations
This article has been cited 6 times.- Attia MM, Soliman SM, Salaeh NMK, Salem HM, Alkafafy M, Saad AM, El-Saadony MT, El-Gameel SM. Evaluation of immune responses and oxidative stress in donkeys: Immunological studies provoked by Parascaris equorum infection. Saudi J Biol Sci 2022 Apr;29(4):2173-2179.
- Malekpour SH, Rakhshandehroo E, Yektaseresht A. Molecular characterization of β-tubulin gene associated with benzimidazole resistance in larvae of field isolates of Parascaris (Nematoda: Ascarididae). J Parasit Dis 2019 Dec;43(4):672-678.
- Bowman DD. Heartworms, macrocyclic lactones, and the specter of resistance to prevention in the United States. Parasit Vectors 2012 Jul 9;5:138.
- Lyons ET, Tolliver SC, Kuzmina TA, Collins SS. Further evaluation in field tests of the activity of three anthelmintics (fenbendazole, oxibendazole, and pyrantel pamoate) against the ascarid Parascaris equorum in horse foals on eight farms in Central Kentucky (2009-2010). Parasitol Res 2011 Oct;109(4):1193-7.
- Lyons ET, Tolliver SC, Ionita M, Collins SS. Evaluation of parasiticidal activity of fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate in horse foals with emphasis on ascarids (Parascaris equorum) in field studies on five farms in Central Kentucky in 2007. Parasitol Res 2008 Jul;103(2):287-91.
- Nielsen MK. Anthelmintic resistance in equine nematodes: Current status and emerging trends. Int J Parasitol Drugs Drug Resist 2022 Dec;20:76-88.
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