Comparative efficacy, persistent effect, and treatment intervals of anthelmintic pastes in naturally infected horses.
Abstract: Eighty horses were involved in a comparative, controlled, and randomised field study conducted in Australia and Brazil. This study was undertaken to address the duration of efficacy (by faecal egg count reduction) of four anthelmintic pastes and to measure the time required between treatments on horses naturally infected by gastrointestinal nematodes. The treatment interval was based on the egg reappearance period (ERP), defined as "the period after treatment when horses have reached a positive egg count equal or superior to 200 eggs per gram (epg) of faeces". Horses were ranked according to pre-treatment faecal egg counts and randomly allocated on Day 0 to one of the four treatment groups (n=16). Group A received a combination of ivermectin at 200 microg/kg and praziquantel at 1.5mg/kg, Group B received an ivermectin paste at 200 microg/kg, Group C received a reference product containing ivermectin at 200 microg/kg, Group D received a moxidectin paste at 400 microg/kg, and Group E received a placebo. Horses were individually faecal sampled at weekly interval from Days 0 to 70 after treatment and coprocultures were made on pooled samples at the pre-treatment time on D-7 in Brazil and D-6 in Australia. The nematode population was mainly composed of small strongyles (Cyathostominae, Gyalocephalus spp., Triodontophorus spp.). All products were efficient (>90% efficacy) until Day 42 with no statistical difference between groups. From Day 49 onwards, Group C reached the threshold, while Group B exceeded this threshold on Day 56. Groups A and D remained below 200 epg for the entire study period (70 days). The interval between two anthelmintic treatments can vary according to the threshold. The ERP was defined as the period after treatment while the output of eggs is negligible or considered as acceptable. The mean number of days calculated to recurrence of 200 epg and more was, respectively, 60 days for product A, 56 days for products B and C, and 64 days for product D. If treatments are combined with other methods of limiting exposure to infective larvae on pasture, the number of treatments required will be reduced even further.
Publication Date: 2001-07-11 PubMed ID: 11445153DOI: 10.1016/s0304-4017(01)00453-8Google Scholar: Lookup
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- Clinical Trial
- Comparative Study
- Journal Article
- Multicenter Study
- Randomized Controlled Trial
Summary
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The study at hand aims to evaluate the efficacy and duration of effect, along with the required treatment intervals, of four different types of anthelmintic pastes on horses naturally infected by gastrointestinal nematodes, in both Australia and Brazil.
Study Design and Groups
- The study was conducted with 80 horses, divided equally into four treatment groups and one control group. Each group had 16 horses, and each horse’s treatment was determined randomly. This approach provided a balanced and unbiased data set for analysis.
- The anthelmintic pastes tested were a combination of ivermectin and praziquantel (Group A), ivermectin paste (Group B), a reference product containing ivermectin (Group C), moxidectin paste (Group D), while Group E received a placebo.
Efficacy Measurement
- The efficacy of the treatments was evaluated through faecal egg count reduction. Horses were individually faecal sampled at weekly intervals from day 0 until day 70 after treatment.
- The main type of nematodes observed were small strongyles (Cyathostominae, Gyalocephalus spp., Triodontophorus spp.).
- Product efficacy was considered satisfactory (>90%) until Day 42 for all four products, with no statistically significant difference noticed between the groups.
Duration of Effect & Treatment Intervals
- To determine the duration of effect of the anthelmintic treatment and the ideal interval between treatments, the egg reappearance period (ERP) was taken into account. This is defined as the time after treatment when egg count in faeces goes back to a count of 200 eggs per gram or above.
- Group C reached this threshold by Day 49 while Group B reached it on Day 56. Groups A and D remained below the threshold for the entire 70-day study period.
- The average number of days for egg count to recur to 200 epg was: 60 days for product A, 56 days for both products B and C, and 64 days for product D.
Conclusions
- Based on the results, if the treatments are combined with other strategies to limit the horses’ exposure to affecting larvae, the number of treatments required could potentially be reduced further.
- This research provides crucial insights for veterinarians, stud farm owners, and horse owners, in formulating effective deworming schedules for horses.
Cite This Article
APA
Mercier P, Chick B, Alves-Branco F, White CR.
(2001).
Comparative efficacy, persistent effect, and treatment intervals of anthelmintic pastes in naturally infected horses.
Vet Parasitol, 99(1), 29-39.
https://doi.org/10.1016/s0304-4017(01)00453-8 Publication
Researcher Affiliations
- Medical Department, Virbac Laboratories, 06511 Cedex, Carros, France. pmercier@virbac.fr
MeSH Terms
- Animals
- Anthelmintics / administration & dosage
- Anthelmintics / therapeutic use
- Anti-Bacterial Agents / administration & dosage
- Anti-Bacterial Agents / therapeutic use
- Australia
- Brazil
- Drug Administration Schedule / veterinary
- Feces / parasitology
- Gastroenteritis / drug therapy
- Gastroenteritis / parasitology
- Gastroenteritis / veterinary
- Horse Diseases / drug therapy
- Horses
- Ivermectin / administration & dosage
- Ivermectin / therapeutic use
- Macrolides
- Nematode Infections / drug therapy
- Nematode Infections / veterinary
- Parasite Egg Count / veterinary
- Praziquantel / administration & dosage
- Praziquantel / therapeutic use
Citations
This article has been cited 7 times.- 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.
- Papini RA, Orsetti C, Sgorbini M. A Controlled Study on Efficacy and Egg Reappearance Period of Ivermectin in Donkeys Naturally Infected with Small Strongyles. Helminthologia 2020 Jun 1;57(2):163-170.
- Saeed MA, Beveridge I, Abbas G, Beasley A, Bauquier J, Wilkes E, Jacobson C, Hughes KJ, El-Hage C, O'Handley R, Hurley J, Cudmore L, Carrigan P, Walter L, Tennent-Brown B, Nielsen MK, Jabbar A. Systematic review of gastrointestinal nematodes of horses from Australia. Parasit Vectors 2019 Apr 29;12(1):188.
- Zak A, Siwinska N, Slowikowska M, Borowicz H, Kubiak K, Hildebrand J, Popiolek M, Niedzwiedz A. Searching for ivermectin resistance in a Strongylidae population of horses stabled in Poland. BMC Vet Res 2017 Jul 3;13(1):210.
- Matthews JB. Anthelmintic resistance in equine nematodes. Int J Parasitol Drugs Drug Resist 2014 Dec;4(3):310-5.
- Bonneau S, Maynard L, Tomczuk K, Kok D, Eun HM. Anthelmintic efficacies of a tablet formula of ivermectin-praziquantel on horses experimentally infected with three Strongylus species. Parasitol Res 2009 Sep;105(3):817-23.
- 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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