Practical aspects of equine parasite control: A review based upon a workshop discussion consensus

Abstract

Development of resistance of several important equine parasites to most of the available anthelmintic drug classes has led to a reconsideration of parasite control strategies in many equine establishments. Routine prophylactic treatments based on simple calendar-based schemes are no longer reliable and veterinary equine clinicians are increasingly seeking advice and guidance on more sustainable approaches to equine parasite control. Most techniques for the detection of equine helminth parasites are based on faecal analysis and very few tests have been developed as diagnostic tests for resistance. Recently, some molecular and in vitro based diagnostic assays have been developed and have shown promise, but none of these are currently available for veterinary practice. Presently, the only reliable method for the detection of anthelmintic resistance is a simple faecal egg count reduction test, and clinicians are urged to perform such tests on a regular basis. The key to managing anthelmintic resistance is maintaining parasite refugia and this concept is discussed in relation to treatment strategies, drug rotations and pasture management. It is concluded that treatment strategies need to change and more reliance should now be placed on surveillance of parasite burdens and regular drug efficacy tests are also recommended to ensure continuing drug efficacy. The present review is based upon discussions held at an equine parasite workshop arranged by the French Equine Veterinary Association (Association Vétérinaire Equine Française, AVEF) in Reims, France, in October 2008.

Circumferential Ileal Rupture due to Verminous Arteritis in a Pony: A Case Report

“…Still, S vulgaris is considered fully susceptible to the anthelmintic drug classes available [3][4][5]9]. To reduce the emergence of anthelmintic resistance, a selective approach of parasite management is encouraged [4]. Strategic intestinal parasite management relies on treating only the horses with fecal egg counts exceeding a predetermined cutoff value, whereas the remaining horses are left untreated [10].…”

“…Still, S vulgaris is considered fully susceptible to the anthelmintic drug classes available [3][4][5]9]. To reduce the emergence of anthelmintic resistance, a selective approach of parasite management is encouraged [4].…”

“…The larval migratory state of this parasite and the resultant complex thromboembolic arteritis of the cranial mesenteric artery and its major branches are well described [1]. Acute death due to gut infarction was commonly reported in horses in the 1950s through to the early 1980s [2], but is now considered an uncommon event [3,4]. Anthelmintic treatment strategies designed to control S vulgaris have been extremely successful in reducing prevalence, morbidity, and mortality from this parasite, and the cyathostomes are now considered the principal strongyloid pathogen of horses [3].…”

Variation in fecal egg counts in horses managed for conservation purposes: individual egg shedding consistency, age effects and seasonal variation

“…The high prevalence and pathogenicity of cyathostomins, coupled with high levels of anthelmintic resistance, places these parasitic nematodes and the study of their epidemiology, at the forefront of research into equine welfare (Nielsen et al 2010a). There are 50 recognized species of cyathostomins, 40 of which have been found in the caecum and colon of horses (Lichtenfels et al 2008).…”

Recommendations for a sustainable control of gastro-intestinal worm infections in horses in Germany

“…Die Situation gibt auch deshalb Anlass zur Besorgnis, weil Anthelminthika mit neuen Wirkmechanismen für die Anwendung beim Pferd in den nächsten Jahren vermutlich nicht zu erwarten sind. Diese Umstände führen dazu, dass sich eine wachsende Zahl von Parasitologen, Tierärzten und Pferdebesitzern für eine nachhaltige Parasitenbekämpfung interessieren (Nielsen et al 2010b (Coles et al 2003). Dabei wird unterstellt, dass die Abtötung dieser Larven zu einer Beschleunigung der Resistenzentwicklung beiträgt.…”