BAER Testing & Deafness
Dalmatians are one of several breeds predisposed to deafness in one or both ears. This particular kind of deafness has been linked with a lack of dark pigment - resulting in white fur (not to be confused with light golden fur seen in breeds like Labrador Retrievers). In 1997 there was a few surveys run to analyse deafness in Dalmatians which found that the approximately 4% of Dalmatians are bilaterally deaf (in both ears).
The BAER (Brainstem Auditory Evoked Response) Test can determine the ears' hearing status individually. It is the only reliable test and a certificate is generated after the test, signed by the practitioner to prove the hearing status of the dog.
Each dog will be given a result, either:
Unaffected (not deaf / bilateral hearing)
Affected - Unilateral (one ear is deaf, one ear is normal)
Affected - Bilateral (the dog is deaf in both ears)
To register as a Kennel Club Assured breeder, the BAER testing of all your dogs is mandatory. Only dogs with normal hearing are to be bred from. Since this has been the case, the incidence of deafness does seem to have reduced but there is yet to be a definitive study to give us an up to date number.
There are a list of Kennel Club recognised testing centres available here:
Further reading: http://www.britishdalmatianclub.org.uk/health/index.php?action=hearing