Health & Testing

BAER Testing in Dogs: Diagnosing Deafness and Who Should Be Tested

BAER testing is the electrophysiological standard for diagnosing deafness in dogs — required for all white-coated, merle, and piebald breeds. Here's how it works.

January 3, 2024 · 5 min read

What BAER Testing Is

BAER (Brainstem Auditory Evoked Response) testing measures the electrical activity in the brain that occurs in response to auditory stimuli. Electrodes are placed on the dog's scalp and clicks are played at known sound levels. The brain's electrical response is recorded — absence of response indicates deafness in that ear. Testing can detect both unilateral (one-ear) and bilateral (both ears) deafness.

Which Dogs Should Be BAER Tested

• Dogs with white or predominantly white coats (Dalmatians, white French Bulldogs, white Bull Terriers)
• All merle dogs — including single merle (M/m), since unilateral deafness is more common than bilateral in merle dogs
• Piebald (parti) dogs with extreme white markings near the ears
• Any dog with suspected hearing impairment — scratching at ears without infection, failure to respond to sounds at expected distances

The Genetics of Inherited Deafness

Congenital hereditary deafness in dogs is linked to a lack of melanocytes in the inner ear — the same pigment-producing cells that create coat color. In white, merle, and piebald dogs, the same genetic mechanisms that reduce pigment in the coat can also reduce or eliminate melanocytes in the cochlear stria vascularis, which is required for normal hearing function. Breeds known for high deafness rates include Dalmatians, Bull Terriers, and merle-heavy herding breeds.

Unilateral vs Bilateral Deafness

Bilaterally deaf dogs (deaf in both ears) often have obvious behavioral signs — no response to sounds. Unilaterally deaf dogs (deaf in one ear) typically appear completely normal behaviorally and can only be identified through BAER testing. Unilateral deafness can still be passed to offspring, which is why BAER testing matters even for dogs that appear to hear normally.