BackgroundOcular melanosis of Cairn terrier dogs is an inherited defect characterized by progressive pigmentation of both eyes which can result in glaucoma and blindness. Pedigree analysis suggests the trait has an autosomal dominant mode of inheritance. We selected 11 potential candidate genes and used an exclusion analysis approach to investigate the likelihood that one of the candidate gene loci contained the Cairn terrier-ocular melanosis locus.ResultsTwo polymorphic loci were identified within or close to each candidate gene. Genotyping of at least 10 ocular melanosis Cairn terriers for each marker showed that there was no single shared allele for either of the two polymorphic markers identified in ASIP, COMT, GPNMB, GSK3B, LYST, MC1R, MITF, SILV, TYR, TYRP1,and TYRP2. This is strong evidence to exclude each locus as the site of the ocular melanosis mutation (probability of a false exclusion calculated for each gene ranged from 1.59 × 10-4 to 1 × 10-9).ConclusionsNone of the 11 potential candidate genes selected are likely to be the gene locus for ocular melanosis in Cairn terriers.