BAER “Brainstem Auditory Evoked Response"
Havanese, like any breed, can have congenital deafness. Baer testing is the only test accepted to confirm the hearing status of your Havanese. Baer is also one of four required tests for a Havanese CHIC number.
There are two types of deafness found in Havanese - acquired and congenital. Congenital (inherited) deafness occurs due to a defective gene that results in a malformation or non-functional ear; it may also result from viral or toxic damage to developing fetus. Congenital deafness in Havanese is permanent.
Acquired deafness occurs for any numbers of reasons. Some causes of hearing loss are head trauma, torn or ruptured ear drum, loud noises, excessive amounts of ear wax, dirt/hair plugging the ear canal; infections of the middle or internal ear; certain medications, liver disorders, general anesthesia and old age. Partial hearing loss and/or deafness are possible in these instances. Degeneration in aged Havanese is the most common cause of acquired deafness. Depending on the cause, acquired hearing loss may be reversible ( ie. Earwax or ear infection).
The main argument in support of BAER testing is that you cannot test hearing yourself. While it may be very obvious if a dog is totally deaf, it can be surprising at how well a deaf or partially deaf dog can learn to compensate. Many owners living with unilaterally deaf dogs are completely unaware of the condition. You would likely not notice anything abnormal if your Havanese had unilateral hearing, especially if your Havanese is in a group with other canines or is a young puppy amongst littermates. Since most canines follow the response of others; this could be true with a Havanese that has unilateral hearing and they may function day to day very normally. Bilateral hearing loss would be more noticeable but your Havanese may still function fairly normally if in a multi canine home especially if it was raised from birth in the same home. Bilateral hearing loss does not necessarily mean that your Havanese would be completely 100% deaf. Some may retain some degree of residual hearing.
You can Baer test your Havanese as young as 35 days old. BAER tests are administered by veterinary neurologists using specialized equipment. BAER is a relatively simple procedure and is completely harmless to your Havanese. It can generally be done without sedation. With a bit of time and patience, even resistant older dogs and wiggly young puppies that don’t like to be restrained can usually relax and settle enough for the procedure to be done. Very rambunctious or uncooperative dogs may require mild sedation though this is very uncommon in Havanese. The test procedure lasts approximately 10-15 minutes. The test is done by placing small electrodes under the skin of the skull. These electrodes are connected to a computer that monitors electrical activity in the brain as it responds to sound stimulus. Sound stimulants are played through small ear plugs inserted into your dog’s ears. Clicking sounds produced by the computer are recorded to monitor the brains’ response.
Each ear is tested separately to confirm that your Havanese has bilateral hearing. Should your Havanese show unilateral or bilateral deafness, it will fail the Baer test; only those having normal bilateral hearing will pass. Once the testing is complete, you will be given a computer print out that can be mailed to OFA for certification.
If the fail is attributed to a correctable problem such as excess ear wax, infection or other such reasons, your Havanese should be retested at a later date once the problem is resolved. Other than correctable transient hearing loss, or loss identified with cetainly as being non-heritable(ie: such as hearing loss resulting from trauma), any Havanese with a failed result should be spayed or neutered and removed from a breeding program as congenital hearing problems are heritable.
There have been some reports of unilateral deafness and a few of bilateral deafness in the Havanese. At this time, it is unknown whether hereditary deafness in Havanese may be linked to colour and or coat pattern as in some other breeds. The Orthopedic Foundation for Animals (OFA) on-line breed stats from February 2009 report 99.6% bilateral normal hearing out of over 3000 Havanese tested. A Baer clinic held at the Havanese Fanciers of Canada National Specialty in 2008 tested 26 Havanese, all with normal results. These wonderful results are reassuring; however do not mean we can be complacent. While bilaterally affected dogs are usually quite noticeable, unilateral deafness is next to impossible to discern without testing. Rates of deafness could rise very rapidly if untested affected dogs are bred. Testing is a simple and easy way to make strides towards reducing congenital deafness in Havanese.
(Condensed version previously published in Dogs in Canada May 2009)