tCrib-biting in horses is a stereotypical oral behaviour with a prevalence of 2.8–15%, varyingbetween breeds. A genetic basis for crib-biting has been suggested by many researchers,but due to incomplete information on families or the lack of a sufficient number of verifiedcrib-biters, heritability has not been determined for any horse population. However, theinvolvement of inheritance in behavioural traits has only been indicated by a few studiesin horses, and evidence for a genetic component in stereotypies mainly comes from studieson other species.Our aim was to estimate the heritability of crib-biting behaviour in a Finnhorse pop-ulation. The cold-blood Finnhorse is a native breed that has been pure-bred since 1907.All Finnhorses are registered in the Finnhorse register, and pedigree data are available formore than 10 generations. A cohort of 111 crib-biting and 285 non-crib-biting (control)Finnhorses were recruited through advertisements. Our hypothesis was that crib-biting isa quantitative trait with a reasonably high heritability (h2), because there is some anecdotalevidence that the trait is expressed in certain families. To the best of our knowledge, this isthe first time that h2has been estimated for crib-biting behaviour in any horse population.The crib-biting behaviour of Finnhorses was described in more detail through an ownerquestionnaire. Crib-biting appears to be performed by Finnhorses in quite a similar way toother breeds. According to the owners, Finnhorses most frequently crib-bite shortly afterfeeding on concentrate or titbits and in stressful situations. The habit typically begins duringthe juvenile years or after some traumatic phase. The proportion of mares among cases wassmaller than among controls.Linear and threshold animal models were tested to estimate the heritability, but the esti-mates did not converge within allowed parameter space. Hence a more robust linear siremodel was used in the final analysis. The estimated heritability of the trait was 0.68. Higherthan moderate heritability suggests for further association studies at the genome leveltogether with pedigree studies to identify risk loci. In addition, resolving genetic correla-tions between performance traits and crib-biting is of great interest for breeding purposes.This study represents a preliminary stage in genetic research of crib-biting.© 2014 Elsevier B.V. All rights reserved.∗Corresponding author. Tel.: +358 50 3482639.E-mail addresses: Karin.hemmann@helsinki.fi (K. Hemmann),marja.raekallio@helsinki.fi (M. Raekallio), outi.vainio@helsinki.fi(O. Vainio), jarmo.juga@helsinki.fi (J. Juga).1. IntroductionCrib-biting in horses is a stereotypical