Adult onset deafness

Adult onset deafness (AOD, early-adult onset deafness, EAOD) is an autosomal recessive hearing disease that is relatively common in Border Collies. The gradual hearing loss is observed usually at the age of 5 to 7 years affecting both ears. The genomic region and related genetic variants associated with the disease have been identified. However, the actual causal mutation has not yet been found but is under active research in our research group. Based on our study cohorts, the carrier frequency of the variants is approximately 30-35% in the Border Collie population worldwide. 

The identification of the genomic region associated with the deafness has enabled the detection of dogs which are at risk to develop AOD or carry the AOD-associated variants. According to the research, the dog homozygous for the deafness-associated variants is at high risk to develop AOD. However, additional larger studies are still needed to investigate whether all homozygous dogs develop AOD in the critical age and whether all lose their hearing completely or some only partially. In addition, more research needs to be conducted to find out whether the heterozygous (carrier) dogs are at risk to develop AOD. If your dog has been genetically tested for AOD and BAER-tested, we wish that you inform us about the results to aid the research. Contact person: Marjo Hytönen, marjo.hytonen(at)