Is crib-biting inherited?

Crib-biting, (or cribbing) is a stereotypic behaviour in which the horse grasps a fixed object with its incisor teeth, and draws air into the cranial oesophagus, before expelling it with a characteristic grunt.

Various factors have been suggested as a cause for the behaviour including gastric discomfort and lack of  sufficient environmental stimulation. But is there a genetic component?

Scientists at the University of Helsinki, Finland compared crib-biting and non-crib-biting horses, looking specifically at genes known or suspected to be related to stereotypic behaviours.

In particular they looked at genes such as Ghrelin, Ghrelin receptor, Leptin, Dopamine receptor, μ-opioid receptor, N-cadherin, Serotonin receptor and Semaphorin.

Two groups of horses were compared. Horses in the crib-biting group had started to display the behaviour at any early age, and had done so for at least a year. They tended to crib-bite after feeding or when stressed.

Non-crib-biting (control)  horses were all over ten years old and had never been seen to crib-bite.

The researchers analysed the candidate genes in both groups and compared the allele frequencies between the cases and controls for each breed separately. They could find no evidence of an association at any of the tested loci.

They conclude: “These results suggest that the previously known stereotypic genes are not major risk factors for crib-biting in horses.” They suggest that further whole genome studies involving larger groups of crib-biting and non-crib-biting horses are required.

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