Early hearing loss in Border Collies (EAOD)

Gradual deterioration of hearing is a relatively common physiological symptom in dogs accompanying aging. At the age around 8 to 10 years the auditory system deteriorates and the ability to detect mid-range and especially higher frequencies decreases. However, Border Collies can also suffer from early hearing loss (EAOD – Early Adult Onset Deafness) and is observed in dogs between the ages of 3 to 5 years. This condition is particularly problematic in Border Collies as the breed is often bred as a working herding dog for whom hearing is a crucial sense. Even the slightest differences in sound frequency perception can significantly affect their working abilities. The first signs of hearing loss can often be very difficult to detect.

The genetic cause and mode of inheritance of early deafness in Border Collies are unknown. Yokoyama et al. (2012) detected four SNP markers in Border Collies associated with an increased risk of developing hearing loss at an unusually young age. These are not causal mutations, but markers that may be linked to a causal mutation that has not been discovered yet and may therefore indicate a possible risk of developing EAOD. Incomplete penetrance of the risk locus may also play a role. It is also possible that early hearing loss is caused by multiple factors. The test result does not indicate whether the dog will actually develop the disease. It only predicts the possible risk of developing early hearing loss. Unfortunately, the degree of risk and probability of deafness associated with individual risk genotypes has not been determined.

List of tested markers (according to CanFam2)

The linkage test can provide breeders with information about whether the dog's genotype is:

• N/N: the individual does not carry any of the tested gene variants
• N/AOD1, N/AOD2, N/AOD3, N/AOD4: the individual carries one copy of the risk gene variant –> risk of developing early hearing loss
• AOD1/AOD1, AOD2/AOD2, AOD3/AOD3, AOD4/AOD4: the individual carries two copies of the risk gene variant –> risk of developing early hearing loss.

Individuals found to be heterozygous or homozygous carriers of risk markers should preferably be selected for breeding pairs with individuals with the N/N genotype. Individuals with proven or progressive hearing loss should not be included in breeding.

Dog owners who have ancestors with deafness in their pedigree should take advantage of the testing option.

The main reason for this is to identify the possible risk of the disease before breeding the dog or training it for work purposes.

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Schmutz, S.M. An analysis of the inheritance pattern of an adult-onset hearing loss in Border Collie dogs. Canine Genet Epidemiol 1, 6 (2014). https://doi.org/10.1186/2052-6687-1-6

Yokoyama JS, Lam ET, Ruhe AL, Erdman CA, Robertson KR, Webb AA, Williams DC, Chang ML, Hytönen MK, Lohi H, Hamilton SP, Neff MW: Variation in genes related to cochlear biology is strongly associated with adult-onset deafness in border collies. PLoS Genet 2012, 8: e1002898. 10.1371/journal.pgen.1002898