Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Königsweg 67, 14163 Berlin, Germany.
Vet Parasitol. 2012 Apr 19;185(1):2-8. doi: 10.1016/j.vetpar.2011.10.010. Epub 2011 Oct 18.
During the past two decades anthelmintic resistance in equine parasites has been found in the group of small strongyle species (cyathostomins) and in the ascarid species Parascaris equorum. The ubiquitous nature and possible severe consequences of disease with these nematodes make them the prime targets of current worm control programmes. Traditional control strategies mainly rely on the strategic application of anthelmintics, currently represented by three major drug classes: benzimidazoles (BZ), the tetrahydropyrimidine pyrantel (PYR) and macrocyclic lactones (ML). Following decades of routine and frequent anthelmintic applications, many cyathostomin populations on horse farms in industrialised countries must be considered as resistant to BZ anthelmintics. However, to date no published cases of cyathostomin disease specifically associated with anthelmintic resistance were reported. Possibly this is due to the generally subclinical and unspecific symptoms associated with cyathostomin infections. Nevertheless, exclusive reliance on the ML drug class may increase the threat of clinical disease due to drug-resistant cyathostomins. More recently, P. equorum has been reported as having developed resistance against ivermectin and moxidectin, two representatives of the ML-class. These anthelmintics are currently the most frequently used drug class in horses. This nematode species is mainly found in foals and in younger horses due to the development of immunity following exposure to infection. Infection with P. equorum can result in clinically drastic consequences such as obstruction and/or penetration of the small intestine, the latter usually leading to death. In conclusion, on horse farms the efficacy of anthelmintic treatments should be examined routinely for each drug class. Several factors can influence the rate at which anthelmintic resistance develops; high frequency of treatment being one of the most important. Modern control strategies should therefore attempt to significantly reduce anthelmintic treatments. Several pasture and farm management practices found to be negatively associated with nematode and anthelmintic resistance prevalence will be discussed in the review presented here.
在过去的二十年中，马属动物寄生虫中的小类圆线虫（Cyathostomins）和副蛔虫属（Parascaris equorum）的驱虫剂耐药性已经被发现。这些线虫的普遍存在和可能导致的严重疾病后果，使它们成为当前蠕虫控制计划的主要目标。传统的控制策略主要依赖于驱虫剂的战略应用，目前主要代表三大药物类别：苯并咪唑类（BZ）、四氢嘧啶吡喃（PYR）和大环内酯类（ML）。经过几十年的常规和频繁应用驱虫剂，工业化国家的许多马养殖场的小类圆线虫种群必须被认为对 BZ 驱虫剂有耐药性。然而，迄今为止，没有报道过与驱虫剂耐药性相关的副蛔虫病的具体病例。这可能是由于与 Cyathostomin 感染相关的通常亚临床和非特异性症状。然而，仅仅依赖 ML 药物类别可能会增加由于 Cyathostomin 耐药性而导致临床疾病的威胁。最近，据报道，副蛔虫对伊维菌素和莫昔克丁（ML 类的两种代表药物）产生了耐药性。这些驱虫剂是目前马最常用的药物类别。这种线虫主要在幼驹和较年轻的马中发现，因为在接触感染后会产生免疫力。感染副蛔虫会导致严重的临床后果，如小肠阻塞和/或穿透，后者通常导致死亡。总之，在马养殖场，应定期检查每个药物类别的驱虫剂治疗效果。有几个因素会影响驱虫剂耐药性的发展速度；治疗频率高是最重要的因素之一。因此，现代控制策略应试图显著减少驱虫剂的治疗。本文综述将讨论几种与线虫和驱虫剂耐药性流行率呈负相关的牧场和农场管理措施。
