hear and now: deafness in pets
Having covered pet blindness in a previous blog, today I'm following up with a blog dedicated to deafness in our furry friends, as the two issues are somewhat linked as far as pet parent worries are concerned. Living with a deaf pet has its challenges (as does living with hearing ones!), but none are so great that they can’t be overcome.
Deafness is the inability of a dog or cat to perceive sound. There are a couple of ways to classify deafness in our pets:
The first two classifications refer to HOW the deafness occurs, and the second two refer to WHY it occurs, physically. Some pets, like some pet parents, are deaf from birth, having inherited it through genetics (due to breed or lineage). Others are born able to hear and become deaf as a result of illness, toxins or age.
Conductive hearing loss
Now on to the WHY: Conductive hearing loss means sound is not being “conducted” through the eardrum – it is a lack of transmission of sound through the eardrum or the tiny bones of the inner ear. It can occur secondary to ear infections (either of the middle or inner ear), which cause fluid buildup in the ear canal. Masses, such as tumors or polyps, can also prevent transmission of sound waves through the ear drum. Less commonly, conductive hearing loss can be a congenital problem, occurring due to the incomplete formation of the external ear or malformation of the bones in the ear.
Sensorineural hearing loss occurs because of abnormalities with the nerves serving the ear or with the higher brain centers, and it can be acquired or inherited. Acquired sensorineural deafness can occur through the use of drugs that are ototoxic (or harmful to the ear), chronic exposure to loud noises, hypothyroidism, trauma and neoplasia. Age-related hearing loss is also considered sensorineural.
Cases of congenital (inherited) sensorineural deafness are often associated with merle, dapple or white coats in dogs. Cats with white coats and blue eyes are more often affected than their pigmented counterparts.
Understanding deafness in pets
Recognizing deafness in our pets may prove difficult, because they often show no obvious signs. This is especially true in pets who have been deaf since birth. Puppies and kittens that are born deaf may be hard to rouse from sleeping, and may vocalize louder than their littermates. They may also play more aggressively, as they can’t hear their littermate’s cries if they play too rough. Pets that become deaf may have a history of ear infections or previous use of ototoxic drugs.
Any dog can have congenital deafness, but several breeds of are predisposed. As we already discussed, dogs with merle or dapple coats (like Collies, Dachshunds, Great Danes and Shetland Sheepdogs) are more often deaf. The long list of other breeds that are predisposed includes Bulldogs, Old English Sheepdogs, Bull Terriers, Cocker Spaniels, Border Collies, Beagles, Foxhounds and Fox Terriers.
Testing for deafness is often done in puppies of predisposed breeds. This is done using a BAER (brain stem auditory evoked response) test. Electrodes are placed on the pet’s head to record a response to an auditory stimulus. BAER testing is generally performed at a referral facility and is usually not pursued in cases of suspected deafness in older dogs.
Adjusting to life with a deaf pet
There is no treatment for deafness, nor is treatment really necessary. Dogs and cats live perfectly happy lives without their hearing, though their environment should be modified accordingly. Leash walking and fenced-in yards should be favored over off-leash walks, since your dog will not hear your calls to “come.” Also make sure to note that your pet is deaf on his or her name tag, so that if she does get separated from you, those who find her will know she’s deaf.
Obedience training may be a little more difficult than in a hearing dog, but teaching hand signals over vocal commands and the use of vibrations will help tremendously. Working together with your deaf pet will only strengthen your bond.