Recognition of affected cases is often difficult, because
unilaterally deaf dogs appear to hear normally unless a special test (the brainstem auditory evoked response, BAER) is performed; facilities to perform the BAER are usually only available at veterinary schools (see list).
The disorder has been reported to have an autosomal recessive mechanism in the Rottweiler, Bull Terrier, and Pointer, but these suggestions are not reliable because the reports were published before the availability of BAER testing and the ability to detect
unilaterally deaf dogs.
Unilaterally deaf dogs are notoriously difficult to identify because they compensate very well for the loss of hearing in one ear.
Dogs that are bilaterally deaf become fairly obvious with time (they don't wake up at meal time or in response to loud noises), but
unilaterally deaf dogs usually go undetected because they respond to sounds with their good ear.
A deaf or
unilaterally deaf dog can make a perfectly fine pet, but they shouldn't be bred and a breeder should do all they can to screen this issue out.
It should be noted that
a unilaterally deaf dog can be as great a genetic risk for transmission of deafness to its offspring as is a bilaterally deaf dog, so BAER testing of puppies from affected breeds is important.
Not exact matches
The likelihood of deafness being present in
dogs with at least one
unilaterally deaf parent has been shown to be significantly greater in the Dalmatian and English Cocker Spaniel breeds, but insufficient data is available from Catahoulas to confirm a similar effect.
Thus, a
dog may be
unilaterally deaf, bilaterally
deaf, or bilaterally hearing.
Behavioral testing by the owner or a veterinarian will not detect
unilaterally deaf animals, and often does not detect bilaterally
deaf dogs because they rely heavily on visual and vibratory cues.
More importantly, it can accurately detect
dogs that are
unilaterally deaf (
deaf in just one ear).