Bellaw Jennifer L, Pagan Joe, Cadell Steve, Phethean Eileen, Donecker John M, Nielsen Martin K
M. H. Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky, Lexington, KY, USA.
Kentucky Equine Research, Versailles, KY, USA.
Vet Parasitol. 2016 May 15;221:69-75. doi: 10.1016/j.vetpar.2016.03.018. Epub 2016 Mar 22.
Parasitic helminths of equids are capable of causing ill-thrift, clinical disease, and death. Although young horses are the most susceptible to parasitic disease and are the most intensively treated cohort, deworming regimens are rarely evaluated within this age group. This study objectively evaluated the impact of deworming regimen on fecal egg counts (FECs), growth rates, and body-condition scores in young Thoroughbreds. Forty-eight Thoroughbred foals from three central Kentucky farms were randomly allocated to two treatment groups: an interval dose program receiving bi-monthly rotations of pyrantel pamoate and ivermectin and a daily deworming group receiving daily rations of pyrantel tartrate feed additive throughout the study, oxibendazole at two months of age, and moxidectin treatments at 9.5 and 16.5 months of age. Pre- and post-treatment eggs per gram of feces (EPGs) of Parascaris spp. and strongyle family parasites, gel/paste dewormer efficacies, and monthly weights and body condition scores were collected. Ascarid and strongyle FECs were not significantly different between groups but were significantly influenced by horse age with strongyle counts continually increasing and ascarid counts peaking at 4.5 months of age. Reduced strongyle efficacies of ivermectin and moxidectin were observed on two farms with consistently low pyrantel pamoate efficacies on all three farms. Ivermectin also exhibited reduced ascarid efficacy. Average daily gain did not differ significantly between groups and was only significantly influenced by age, mirroring average daily gain reference data for Kentucky Thoroughbreds born in 2013. Body condition scores also did not differ between groups, remaining in the optimal range (5-6) for the duration of the study. Management practices resulting in growth rates matching the reference data and in optimal body condition scores compensate for the negative impacts of parasitism even in cases of reduced drug efficacy. Performance parameters can provide useful information in cases of suboptimal parasite control.
马的寄生蠕虫能够导致生长发育不良、临床疾病甚至死亡。虽然幼马最易感染寄生虫病，也是接受治疗最密集的群体，但驱虫方案在这个年龄组中很少得到评估。本研究客观评估了驱虫方案对纯种幼马粪便虫卵计数（FEC）、生长速度和体况评分的影响。来自肯塔基州中部三个农场的48匹纯种马驹被随机分配到两个治疗组：一个间隔给药方案，每两个月交替使用吡喹酮和伊维菌素；一个每日驱虫组，在整个研究期间每天给予酒石酸噻嘧啶饲料添加剂，在2月龄时给予奥苯达唑，在9.5月龄和16.5月龄时给予莫西菌素治疗。收集治疗前后每克粪便中副蛔虫属和圆线虫科寄生虫的虫卵数（EPG）、凝胶/糊状驱虫药的疗效以及每月体重和体况评分。两组之间蛔虫和圆线虫的FEC没有显著差异，但受马年龄的显著影响，圆线虫计数持续增加，蛔虫计数在4.5月龄时达到峰值。在两个农场观察到伊维菌素和莫西菌素对圆线虫的疗效降低，而在所有三个农场中，吡喹酮的疗效一直较低。伊维菌素对蛔虫的疗效也有所降低。两组之间的平均日增重没有显著差异，且仅受年龄显著影响，这与2013年出生的肯塔基州纯种马的平均日增重参考数据一致。两组之间的体况评分也没有差异，在研究期间一直保持在最佳范围（5-6）。即使在药物疗效降低的情况下，能使生长速度与参考数据匹配并使体况评分保持最佳的管理措施也能弥补寄生虫感染的负面影响。在寄生虫控制不理想的情况下，性能参数可以提供有用的信息。
