The following reports have been written by George M. Strain, PhD
The hearing test known as the brainstem auditory evoked response (BAER) or brainstem auditory evoked potential (BAEP) detects electrical activity in the cochlea and auditory pathways in the brain in much the same way that an antenna detects radio or TV signals or an EKG detects electrical activity of the heart. The response waveform consists of a series of peaks numbered with Roman numerals: peak I is produced by the cochlea and later peaks are produced within the brain. The response from an ear that is deaf is an essentially flat line.
Because the response amplitude is so small it is necessary to average the responses to multiple stimuli (clicks) to unmask them from the other unrelated electrical activity that is also present on the scalp (EEG, muscle activity, etc). The response is collected with a special computer through extremely small electrodes placed under the skin of the scalp: one in front of each ear, one at the top of the head, and one between and behind the eyes. It is rare for a dog to show any evidence of pain from the placement of the electrodes - if anything the dog objects to the gentle restraint and the irritation of wires hanging in front of its face. The stimulus click produced by the computer is directed into the ear with a foam insert earphone. Each ear is tested individually, and the test usually is complete in 10-15 minutes. Sedation or anesthesia are usually not necessary unless the dog becomes extremely agitated, which can usually be avoided with patient and gentle handling. A printout of the test results, showing the actual recorded waveform, is provided at the end of the procedure.
I agree with the official policy of the Dalmatian Club of America that bilaterally deaf puppies should be put down by breeders instead of being placed. For every story of someone who has successfully raised and owned a deaf dog, there are two or more of people who tried and only got heartbreak and incredible problems as a result.
I feel that all responsible breeders in those breeds with a significant deafness incidence problem are morally obligated to have their puppies BAER tested before placing them, should put down those that are bilaterally deaf, and should only sell with a spay/neuter contract those puppies that are unilaterally deaf. And even before dealing correctly with any affected puppies, they should not accept any breeding where even one parent is unilaterally deaf, and should insist on proof that the dog or bitch to which they wish to breed has been BAER tested and is bilaterally hearing. From data I have collected on hearing tests of about 4,500 Dalmatians, if only one parent is unilaterally deaf, the probability nearly DOUBLES that any offspring will be unilaterally deaf or bilaterally deaf. Eight percent of all Dalmatians are bilaterally deaf and 22% are unilaterally deaf - a 30% total with some deafness.
As a result, it is fairly safe to say that no line or champion cannot produce deaf offspring. The available evidence suggests that more than one gene is involved in producing deafness; it is impossible to predict at this time when a breeding will combine the genes to produce a deaf dog. It is also important to understand that a unilaterally deaf dog has the genetic defect, it was just fortunate enough that one ear was spared for some unknown reason. So, breeding it is as bad as breeding a bilaterally deaf dog.
I have a breeding colony of 1 deaf dog and 4 deaf bitches that I use in my research. They are delightful animals, but I would not want them in my home or around my children or those of others. One snapped at one of my sons. Not all deaf dogs ultimately develop aggressive or anxious personalities, but there is no way to predict which will or will not, and those that do are the ones that attack neighbors or family members. They often end up in animal control centers and/or are put down. Deaf dogs are an incredible challenge to raise and train. It can be done - many quickly learn to respond to hand signals and other indicators such as a flashed porch light or training shock collars set to the lowest intensity. Nevertheless, for the most part they are a disaster waiting to happen. When there are so many Dalmatians available these days, it doesn't make sense to hang on to those with a genetic defect, one that is not immediately life-threatening, but promises so much trouble and pain. Is it fair to the dog to subject it the kind of life it may face, with emotional disturbances and always being startled and frightened? I don't think so.
I do NOT take the position that unilaterally deaf dogs should be put down. On the contrary, they make excellent pets and owners are unlikely to be able to detect any abnormality. However, they should not be bred.
Recently I was consulted by a woman with physical handicaps who had purchased (at a reduced price!) a deaf 3 month old puppy. Now at age 3 years it is attacking her other dog, jumps up on the kitchen table and other furniture, becomes viciously aggressive when anyone (human or animal) comes between her and food, could not complete an obediance training class with a trainer experienced with deaf dogs, and is totally out of control. She was considering trying to place it with another owner until I convinced her otherwise. She really has no alternative other than euthanasia.
To learn more on animal deafness Visit George M. Strain, PhD Website at http://www.lsu.edu/guests/senate/public_html/deaf.htm
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