title: Exploration of known stereotypic behaviour-related candidate genes in equine crib-biting.
abstract: 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.
authors.affiliation: 1Faculty of Veterinary Medicine, Department of Equine and Small Animal Medicine, University of Helsinki, Koetilantie 7, P.O. Box 57, 00014 Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Hemmann
authors.affiliation: 2 Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Finland and the Folkhälsan Institute of Genetics, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Ahonen
authors.affiliation: 1Faculty of Veterinary Medicine, Department of Equine and Small Animal Medicine, University of Helsinki, Koetilantie 7, P.O. Box 57, 00014 Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Raekallio
authors.affiliation: 1Faculty of Veterinary Medicine, Department of Equine and Small Animal Medicine, University of Helsinki, Koetilantie 7, P.O. Box 57, 00014 Helsinki, Finland.
authors.forename: O
authors.initials: O
authors.lastname: Vainio
authors.affiliation: 2 Department of Veterinary Biosciences and Research Programs Unit, Molecular Neurology, University of Helsinki, Finland and the Folkhälsan Institute of Genetics, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Lohi
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D005260:Female; D020022:Genetic Predisposition to Disease; D006736:Horses / Q000235:genetics* / Q000502:physiology; D008297:Male; D036361:Peptide Hormones / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D018000:Receptors, Peptide / Q000235:genetics*; D013239:Stereotyped Behavior
chemical_list: D036361:Peptide Hormones; D018000:Receptors, Peptide