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Chocolate Havanese

BAER - hearing test

Hereditary deafness in Havanese, while only mentioned recently, is not a new problem. Deaf Havanese have been appearing sporadically for years, but breeders thinking it was an isolated incident, rarely shared the information. This heritable disorder has a complex mode of inheritance it appears that affected Havanese (unilateral or bilateral) are particoloured of some kind, (parti, piebald, extreme) or all white. Solid colour Havanese tested so far are normal in both ears. Only dogs carrying or displaying these colour/pattern genes are vulnerable, and not all of them have inherited the mutation which causes the problem so this does NOT mean that all parti/ white Havanese are deaf, just that all the affected dogs to date are parti or white.

You cannot check hearing yourself. Most people with unilaterally affected Havanese are completely unaware that a problem exists. Hearing status can be positively ascertained by a Brainstem Auditory Evoked Response test (BAER) which detects electrical activity in the ear and auditory pathways in the brain . It is a very simple test and can be done anytime after a puppy is about 6 weeks old. It is a one time test. The ears should be clean and free of infection, wax build-up and hair overgrowth as these may affect test results. The test takes approximately 10-15 minutes to complete. Each ear is tested individually. Small ear phones deliver the stimulus and response data is collected through tiny electrodes with the results being displayed on a computer screen. A normal response waveform shows a series of peaks and valleys while the response from a deaf ear is essentially a flat line. Dogs show no evidence of discomfort from the electrodes though they may object slightly to the gentle restraint. Sedation is generally unnecessary in Havanese; even young puppies take the test in stride. At the end of the procedure, the recorded waveform is printed out.

BAER testing can be difficult to locate though is available at veterinary colleges. A test for a single dog may be expensive but prices are substantially lower if done with multiple dogs or at a hearing clinic. Some Veterinary colleges have recently acquired portable equipment which may make BAER clinics more easily accessible in upcoming years. At this time, among those affected, there appears to be many more unilaterally than bilaterally affected Havanese, but incidence may rapidly rise as untested unilaterals are bred together. Caution should be exercised when considering breeding known unilateral deaf dogs as the likelihood of deafness may be significantly increased in litters with unilaterally deaf parent(s). Until a test for this gene mutation is developed, BAER testing breeding stock and puppies prior to placement is one way to help minimize the incidence of deafness in our breed.