DEAFNESS IN DALMATIANS
At present, approximately 13.6% of Dalmatians tested at the Animal Health Trust are unilaterally deaf (deaf in one ear), while 4.9% are bilaterally deaf (deaf in both ears). The lower prevalence of deafness in Dalmatians we test (18.5% affected), where blue eyed dogs are not bred from, when compared with the US population (29.7% affected), where blue eyed dogs are used as breeding stock, seems to imply that removing blue eyed individuals from the breeding population could reduce the prevalence of affected offspring. This is supported by recent information from the US, which shows a statistically significant relationship between deafness and blue eyes.
The anatomical changes that take place in the inner ear due to this disorder have been extensively studied. Microscopic examination has shown that the deafness that affects Dalmatians is caused by degeneration of the blood supply to the cochlea (a spiral-shaped structure in the inner ear). in the first few weeks of life. This is followed by destruction of the hair cells and ultimately further deterioration of components of the inner ear and nerve degeneration. The loss of the hair cells is permanent and irreversible. The passage of sound to the auditory nerve is interrupted, i.e. sound cannot “get in” to the auditory pathway, resulting in the dog becoming deaf.
For further information about BAER deafness testing at the AHT, please visit our Deafness page.