A questionnaire study on parasite control practices on UK breeding Thoroughbred studs.
ABSTRACT Improved education of veterinarians and equine owners/managers is essential in implementing parasite control strategies that are less reliant on chemicals.
This questionnaire study, conducted on 61 UK Thoroughbred (TB) establishments during 2009 and 2010, was designed to obtain an understanding of current helminth control practices on studs. To our knowledge, this is the first occasion that statements obtained from TB studs via questionnaire have been supported by statistical analysis.
Despite many respondents indicating high levels of concern regarding anthelmintic resistance, 56% of these establishments that received visiting equines co-grazed these animals with permanent stock and <74% administered anthelmintics prior to integration. In the 12 months preceding the study, most respondents administered frequent macrocyclic lactone (ML) treatments, with none appearing to leave any animals in groups untreated at each administration. Indiscriminate whole group treatments with MLs and movement of animals to 'clean grazing' post treatment (reported by >25% of respondents), indicates that many stud owners/managers are not aware of the strong risk factors for the development of anthelmintic resistance. Few studs had conducted faecal egg count (FEC) analysis in the past and only 22% indicated that they considered this form of analysis beneficial in determining anthelmintic choice.
The challenge now is to convince stud owners/managers to deviate from their current practices to control strategies that are more likely to preserve anthelmintic efficacy. Veterinarians need to get more involved in implementing these control strategies, with better emphasis placed on the role of diagnostic tests in facilitating targeted treatments and in investigating anthelmintic sensitivity in the associated nematode populations.
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ABSTRACT: The level of anthelmintic resistance within some cyathostomin parasite populations has increased to the level where sole reliance on anthelmintic-based control protocols is not possible. Management-based nematode control methods, including removal of faeces from pasture, are widely recommended for use in association with a reduction in anthelmintic use to reduce selection pressure for drug resistance; however, very little work has been performed to quantitatively assess the effectiveness of such methods. We analysed data obtained from 345 donkeys at The Donkey Sanctuary (Devon, UK), managed under three different pasture management techniques, to investigate the effectiveness of faeces removal in strongyle control in equids. The management groups were as follows: no removal of faeces from pasture, manual, twice-weekly removal of faeces from pasture and automatic, twice-weekly removal of faeces from pasture (using a mechanical pasture sweeper). From turn-out onto pasture in May, monthly faecal egg counts were obtained for each donkey and the dataset subjected to an auto regressive moving average model. There was little to no difference in faecal egg counts between the two methods of faecal removal; both resulted in significantly improved cyathostomin control compared to the results obtained from the donkeys that grazed pasture from which there was no faecal removal. This study represents a valuable and unique assessment of the effectiveness of the removal of equine faeces from pasture, and provides an evidence base from which to advocate twice-weekly removal of faeces from pasture as an adjunct for equid nematode control. Widespread adoption of this practice could substantially reduce anthelmintic usage, and hence reduce selection pressure for nematode resistance to the currently effective anthelmintic products.Parasites & Vectors 01/2014; 7(1):48. · 3.25 Impact Factor
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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.Veterinary Parasitology 05/2014; 202(3-4):95-103. · 2.38 Impact Factor
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ABSTRACT: Anthelmintic drugs have been applied indiscriminately to control horse nematodes for over 40 years. We undertook a comprehensive study to investigate efficacy of the four available broad-spectrum anthelmintic drugs on 16 Thoroughbred stud farms using the faecal egg count reduction test (FECRT). Efficacy against strongyles was determined by calculating the percentage of reduction in faecal egg count (FEC) between the group mean at Day 0 and Days 14 - 17 post-treatment and the 95% lower confidence intervals (LCL) estimated by non-parametric bootstrapping. Individual strongyle FECRTs (n = 429) were performed in which 179, 131, 89 and 30 horses were administered ivermectin (IVM), moxidectin (MOX), pyrantel (PYR) and fenbendazole (FBZ), respectively. MOX was efficacious in all tests (FECR range: 99.8 - 100%; 95% LCL range: 96.8 - 100%) and reduced efficacy of IVM (FECR range: 85.7 - 100%; 95% LCL range: 65 - 100%) was observed in one group of yearlings. Reduced PYR efficacy was observed in five groups of yearlings (FECR range: 0 - 73%; 95% LCL range: 0 - 59.5%), but PYR was found to be efficacious when administered to mares (FECR range: 98 - 99.4%; 95% LCL range: 91.8 - 99.3%). Low efficacy of FBZ was always observed (FECR range: 0.4 - 41%; 95% LCL not calculable). Two further methods for estimating efficacy were applied and outputs obtained using all methodologies were in agreement. Efficacy against Parascaris equorum was assessed on four farms: FBZ had acceptable efficacy (FECR range: 97.5 - 99.9%; 95% LCL range: 96.3 - 99.1%), but reduced efficacy of IVM was observed (FECR range: 25.5 - 91.2%; 95% LCL range: 6.7 - 82.4%). Strongyle FEC were analysed at approximately 2 week intervals for up to 12 weeks after anthelmintic drug administration to determine the egg reappearance period (ERP) for MOX, IVM and PYR. The ERP for all three anthelmintic drugs was shorter than previously observed. Overall, our results indicate that IVM and MOX administration provided acceptable efficacy at 14 days; however, ERP results suggest that these products are working less effectively than measured previously. As shortened ERP is believed to be an early indicator of resistance, this highlights the issue of impending multi-drug resistance in strongyles on stud farms.International journal for parasitology 04/2014; · 3.39 Impact Factor