Inherited Deafness in Dogs

Are you suspicious about the hearing of your beloved pet? This is a real concern for pet owners of some breeds of dogs. Inherited deafness in dogs usually develops within the first few weeks or months of life while the ear canals are still developing. This malady can be total, bilateral or unilateral and is usually permanent.

Inherited deafness in dogs is defined as the absence of sound or the reduction of sound. This can be hereditary or acquired, sensorineural or conductive.

The symptoms of deafness in dogs is very similar to those noted in humans, specifically an inability to hear sounds and audible stimuli. If the deafness is bilateral or complete, your beloved pet will simply not hear and respond to your commands or sounds outside his visual field. If the deafness is unilateral, this means he doesn’t hear from one ear only but the other ear most likely picks up sounds normally. Fido or Fifi will hear and respond to the sound but not necessarily know from whence it came unless one of the other senses picks up and fills in the blanks. One might also notice symptoms of imbalance along with the decreased responses to sounds. What might this look like in your dog? There will be stumbling, staggering and perhaps even a head tilt to one side or the other. What you don’t have is pain, suffering, decreased quality of life or length of life in your beloved pet.

Types

Inherited hearing loss can be total, bilaterla, or unilateral.

There are several causes for deafness in dogs. There is really no prevention or cure for inherited deafness in dogs. The hereditary deafness can be classified as cochleosaccular, neuroepithelial, or congenital in origin.

Cochleosaccular is a type that is generally linked to pigment genes in their coats and blue eyes. There are two genes which have an effect on the pigment of the hair of the animal. The merle gene causes white pigment and has been associated with deafness in dogs. The other gene is called piebald gene and it results in multi-colored patches of fur in the coat of the animal. This defect was noted as early as 1859 in dogs and 1828 in cats. These defects can cause deafness in other species like equine, bovine and porcine. This pigment defect has been linked to hair cell loss.

Neuroepithelial deafness is the one that has not been linked with pigment patterns, it tends to be unilateral, and results from hair cell loss in the same time frame as the cochleosaccular type. It is this type that can also result in balance issues if there is vestibular involvement as has been noted in Doberman Pinschers.

Congenital deafness is considered to be hereditary as well. It has been noted in 100 dog breeds and is especially prevalent in those animals who carry the piebald gene like Australian Cattle Dog, English Setter, English Cocker Spaniel, Dalmatian, Bull Terrier,Boston Terrier and the Parson Russell Terrier, and in other different breeds who carry the merle gene as well.

First of all, there is no DNA testing currently available that can identify those merle and piebald genes that are responsible for the development of deafness in the early weeks and months of life of your pet so there is no way to absolutely know if the puppy you’ve fallen in love with will have an inherited deafness. BAER (Brainstem Auditory Evoked Response) testing is the best way to test for unilateral deafness since it can go undetected by other means. This testing is generally done in a referral setting while behavioral testing is usually done in the clinical setting. Both types of testing require observance and analysis of responses illicited by audible stimulus. They’re looking for some sort of response to signify that the animal is aware of the stimulus that is outside their normal visual field.

The behavioral testing done in the clinic setting has its limitations, however:

• Inability to identify deafness that is unilateral
• Sometimes stimulus can be detected by the animal through other senses
• There can be blunted responses in animals who are stressed
• The responses can fail with boredom from repeated stimulus

You’re likely to notice the hearing deficiencies when your pet fails to awaken to an auditory stimulus that isn’t noted by another sense, like the sense of smell or vision. Or, when he doesn’t respond to a verbal / audible command given to him from outside his normal field of vision.

Once the hereditary deafness diagnosis has been obtained, there is no treatment for it. The hearing loss, whether bilateral, complete or unilateral is permanent. The good thing is that your pet is not suffering from any pain or decrease in quality of life. Adjustments will have to be made in your lifestyle especially if the deafness is total or bilateral such as touching or visual stimulus to enable communication with your pet.

If you have a dog who suffers from inherited deafness, it would not be a good idea to breed your pet as the gene can be passed to offspring. Spaying or neutering is a great alternative to avoid accidental breeding. Just love them anyway and enjoy the wonderful world of companionship that goes along with having a family pet.