Description:
Abstract Objective—To use pedigree analysis to evaluate thefeasibility of a major locus model for deafness inDalmatians. Animals—605 purebred Dalmatians from 42 families. Procedure—Hearing loss was evaluated through thebrainstem auditory-evoked response. Dogs wereclassified into mutually exclusive categories: normalhearing, unilaterally deaf, or bilaterally deaf.Information was collected on sex, coat color, presenceor absence of a color patch at birth, and eyecolor. Statistical analyses were performed by use ofregressive logistic models designed for complex segregationanalysis. Genetic correlations among eyecolor, deafness, and color patch were estimated. Results—Prevalence of hearing loss was 11% fordogs classified as unilaterally deaf and 5% for dogsthat were bilaterally deaf. Complex segregation analysisdetected statistical evidence of a single allele withan expected frequency of 0.21 that had an effect onthe prevalence of deafness. Results of analyses suggestedthat this locus cannot completely explain theinheritance and incidence of deafness in Dalmatians.Genetic correlation estimates among deafness, eyecolor, and color patch revealed strong interrelationshipsamong these characteristics. Conclusions and Clinical Relevance—To reduce theincidence of hearing loss in Dalmatians, unilaterallydeaf, blue-eyed dogs should not be considered aspotential parents. ( Am J Vet Res 2000;61:550–553)