An update on cyathostomins: Anthelmintic resistance and diagnostic tools

Abstract

SummaryCyathostomins represent a potential cause of equine morbidity and have become the main focus of endoparasite control in managed horses. All grazing horses are at risk of infection with cyathostomins; therefore, the application of appropriate management measures is essential. Anthelmintics currently comprise the main method of control for equine nematodes and the ready availability of these products in some countries has resulted in their use becoming dissociated from veterinary involvement. This is concerning given the levels of anthelmintic resistance that have been recorded in cyathostomin populations. It is important that veterinarians re-establish control over the implementation of parasite control programmes, a major objective of which should be the preservation of anthelmintic efficacy. This article details the principles of cyathostomin control in horses with particular reference to anthelmintic resistance, and the use and interpretation of diagnostic tests for detecting cyathostomins and identifying anthelmintic resistance.

Sub-optimal efficacy of ivermectin againstParascaris equorumin foals on three Thoroughbred stud farms in the Manawatu region of New Zealand

“…The other nematodes likely to afflict foals of this age group also need to be considered in any helminth control programme and it has long been acknowledged that the small strongyle (cyathostome) nematodes of horses in New Zealand are already likely to be BZ-resistant, just as they are overseas (Stratford et al 2011). In work in New Zealand, Hope and Kemp (1980) showed that fenbendazole did not reduce the cyathostome FEC of five yearlings, whilst in unpublished work, also from the early 80s, McPherson and Cairns 1 tested mebendazole on nine properties and its efficacy varied from 23-92% (mean 64%).…”

Anthelmintic resistance in equine helminth parasites – a growing issue for horse owners and veterinarians in New Zealand?

“…At various times, and in light of the above, many have argued that more effective use should be made of information such as faecal egg counts in deciding whether a horse should be treated or not. These calls were made more than two decades ago (Duncan and Love 1991;Gomez and Georgi, 1991) and have received renewed backing more recently (Reinemeyer 2009;Kaplan and Nielsen 2010;Stratford et al 2011).…”

Drug Resistance or Re-Emergence? Simulating Equine Parasites

“…In the European Union (EU), a directive issued in 2006 included similar prescription-only restrictions, which have been adopted by an increasing number of member countries. Altogether, selective therapy is recommended worldwide for equine parasite control [Stratford et al 2011;Becher et al 2010;Kaplan and Nielsen 2010] and can now be considered a general trend. It is unclear to what extent these recommendations have been successful in reducing further development of anthelmintic resistance in equine parasites, but surveys suggest that anthelmintic resistance occurs at lower levels in Denmark compared to other countries [Larsen et al 2011;Nielsen 2009].…”