Deafness associated with pigmentation phenotypes in North American yaks (Bos grunniens).

Objective: To assess the presence of suspected pigment-associated deafness in North American yaks (Bos grunniens).

Animals: 12 North American yaks, including 11 with the homozygous piebald Royal pigmentation phenotype and 1 with the heterozygous piebald Trim phenotype.

Procedures: Hearing was assessed using the brainstem auditory evoked response (BAER) on yaks restrained in the head gate of a grooming chute.

Results: Five of the Royal yaks and the Trim yak had hearing in both ears. Six Royal yaks were affected; 3 were deaf in 1 ear and 3 were deaf in both ears.

Clinical Relevance: For the first time, probable sensorineural deafness has been confirmed to be present in Royal yaks. The disorder is assumed to be congenital and associated with white pigmentation, based on the pattern of occurrence in other species.