1Faculty of Veterinary Medicine, Department of Equine and Small Animal Medicine, University of Helsinki, Koetilantie 7, P.O. Box 57, 00014 Helsinki, Finland.
2 Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Finland and the Folkhälsan Institute of Genetics, Finland.
Animal. 2014 Mar;8(3):347-53. doi: 10.1017/S1751731113002346. Epub 2014 Jan 6.
Crib-biting in horses is a stereotypic oral behaviour. Genetic susceptibility has been suggested on a causal basis, together with environmental factors such as stress, gastric discomfort and frustration caused by stall restrictions. This study aimed to test the associations of known or suspected stereotypic genes with equine crib-biting, including Ghrelin, Ghrelin receptor, Leptin, Dopamine receptor, μ-opioid receptor, N-cadherin, Serotonin receptor and Semaphorin. We conducted a candidate gene study with a case-control design, including 98 crib-biting and 135 control horses of two breeds, Finnhorses and half-breds. Detailed phenotypic information on crib-biting behaviour was surveyed through an owner-completed questionnaire. Control horses were more than 10 years old and without a history of crib-biting. Single nucleotide polymorphisms flanking the candidate genes were genotyped using either Sanger sequencing or Taqman assays. According to the survey, the affected horses started crib-biting at a young age, had exhibited crib-biting for more than a year, and expressed the behaviour after feeding or when stressed. Comparison of allele frequencies between the cases and controls for each breed separately did not provide evidence of an association at any of the tested loci. These results suggest that the previously known stereotypic genes are not major risk factors for crib-biting in horses, and further genome-wide studies are warranted on larger sample cohorts.
马啃咬是一种刻板的口腔行为。基于因果关系，遗传易感性与环境因素（如压力、胃部不适和马厩限制引起的挫折感）一起被认为是导致这种行为的原因。本研究旨在测试已知或疑似刻板行为基因与马啃咬之间的关联，这些基因包括 Ghrelin、Ghrelin 受体、Leptin、Dopamine 受体、μ-阿片受体、N-钙黏蛋白、Serotonin 受体和 Semaphorin。我们进行了一项候选基因研究，采用病例对照设计，包括 98 匹啃咬马和 135 匹芬尼霍斯马和混血马的对照马。通过所有者完成的问卷对啃咬行为的详细表型信息进行了调查。对照马的年龄超过 10 岁，且没有啃咬史。使用 Sanger 测序或 Taqman 测定法对候选基因侧翼的单核苷酸多态性进行了基因分型。根据调查，受影响的马在年幼时开始啃咬，啃咬行为已经持续了一年多，并且在进食或感到压力时表现出这种行为。对每个品种的病例和对照之间的等位基因频率进行比较，没有在任何测试的基因座上提供关联的证据。这些结果表明，先前已知的刻板基因不是马啃咬的主要危险因素，需要在更大的样本队列中进行全基因组研究。
