The hearing test known as the Brainstem Auditory Evoked Response (BAER) 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.
This test records brain responses to click sounds delivered to an ear. It does not require a behavioral response from the animal, hence no chance of misinterpretation of a dog's response. The test can be done quickly (with the appropriate equipment), and will give a definitive record of each ear's response to sound. The BAER is currently being used to eliminate or reduce the incidence of genetic expression of deafness from several breeds of dogs (i.e., Dalmatians, English Setters). Since deafness is a genetic defect, and since it appears essentially at 2-3 weeks of age, testing the pup anytime after 5 weeks of age with the BAER has become an excellent way to identify the auditory status of individual dogs. This deafness trait has not been observed to develop gradually in dogs, and does seem to be an all-or-none situation for each ear.
Bilateral - deaf in both ears (i.e., totally deaf)
Unilateral - deaf in one ear (often called "unis")
Here are some basic steps that responsible Jack Russell Terrier breeders can take to reduce deafness in Jack Russells.
- BAER test all breeders and NEVER breed a totally deaf or unilaterally deaf individual.
- BAER test ALL litters of puppies BEFORE they leave your kennel to go to new homes.
- Avoid repeating a breeding that produces deafness.
- Responsible stud dog owners should never breed to a bitch that has not been BAER tested.
- In most cases, do not place or keep a totally deaf individual. It takes a VERY special person to raise and train a deaf dog and the club does not recommend it because of everything it involves. Fear biting is just one of many problems. However, there are books on the subject that can help an owner train a deaf terrier.
- Seek normal pet homes for unilaterally deaf puppies but insist on them being spayed or neutered at the earliest suitable age and NEVER provide pedigree and stud certificate paperwork that is not clearly marked that the individual is unilaterally deaf.
BAER Testing Clinics
- Cornell University Vet School, Ithaca, NY
- Animal Medical Center, NY, NY
- Tufts University, Boston area, MA
- Auburn University in Auburn, Alabama
- Veterinary School at the University of Missouri in Columbia, MO
- Additional Testing Sites (by State)