By Teresa Garden, DVM
It can be a source of great concern for most pet owners if they detect their pet may be hard of hearing or even deaf. In most cases the cause is either treatable or a normal part of the aging process. How do you know if your pet is experiencing hearing loss? The main sign to watch for is your pet will not respond to environmental noises. An example would be failure to wake up with the rest of the pets in your household. Deaf pets will not respond to the doorbell and may no longer greet you when you come home. They may no longer respond to typical household noises such as a door slamming. They may not respond when you call their name or squeak their favorite toy. They tend to startle easily. There are various causes of hearing loss. Some are treatable and some are not. Some are temporary and some are permanent.
Congenital or hereditary deafness is the most common cause of deafness in dogs. It is often associated with dogs having white hair or blue eyes. It is also noted in dog breeds carrying the merle or piebald gene. This type of deafness can be present at birth or may be progressive as the animal matures. Breeds affected include the Dalmation, Australian Blue Heeler, English Setter, Argentine Dogo, Bull Terrier, Jack Russell Terrier, Australian Shepherd, and Cavalier King Charles Spaniel. There is no treatment or cure for this type of deafness. Breeders are encouraged to stop the breeding of lines that produce deaf offspring. Early screening of breeds with a predisposition for hereditary deafness is strongly recommended.
Age-related hearing loss will usually occur in dogs 12 to 15 years old. This type of hearing loss is referred to as “sensorineural” hearing loss. It results from missing or damaged sensory cells (hair cells) in the cochlea of the inner ear. Damage to the auditory nerve in the brain can cause neural hearing loss. These types of hearing losses are permanent although often not complete. Dogs can often still hear high-pitched sounds. Before diagnosing “old age” as the cause of a hearing deficit, other causes of hearing loss should be ruled out.
Ear infections afflicting both ears can lead to a loss of hearing. Symptoms of ear infections are scratching at the ears, shaking the head, odor or discharge from the ear, and red or scabby ears. Your veterinarian can diagnose an ear infection by conducting a physical exam and performing cytology on any debris or discharge found in the ear(s). Most ear infections are caused by yeast, bacteria, or ear mites. These infections can be successfully treated by cleaning the ear canals and instilling topical medication. If the infection has caused hearing loss, the deafness is usually temporary. Ear infections that do not resolve with treatment may have underlying causes such as allergies, thyroid disease, or adrenal disease.
If you suspect your dog may be becoming deaf it is a good idea to have your veterinarian check his thyroid levels with a blood profile. There are many symptoms a dog may have if he is hypothyroid. Typical symptoms are unexplained weight gain, thinning haircoat, increased drinking and urination, and lethargy. But hypothyroidism can affect the nervous system resulting in neuropathy and hearing loss. Once properly diagnosed, hypothyroidism can be successfully treated and symptoms will resolve.
Hearing loss is now thought to be associated with some cases of canine cognitive dysfunction (senility). Perhaps the hearing loss is caused by cognitive dysfunction but we are not sure of this at this time. Senior and geriatric dogs are afflicted with cognitive dysfunction. Symptoms include loss of house training, sleep cycle disturbance, pacing, barking, and whining for no apparent reason, and getting lost and confused in the home. Cognitive dysfunction can be managed but not cured. Supplements such as Senilife and Neutricks can be very helpful along with antioxidants, omega-3 fatty acids, and Ginkgo bilboa. Anxiety associated with senility can be improved with Bach flowers, calming herbs, and nutritional supplements such as Composure or Zelkeyne.
Hearing loss in older pets could also be caused by organic brain disease. Organic brain disease is very serious and will usually have a myriad of symptoms such as seizures, depression, blindness, paralysis, circling, stumbling, and ataxia. Advanced imaging studies such as a CT scan or MRI are needed to diagnose organic brain disease.
Examples of organic brain disease include encephalitis, brain tumor, and granulomatous meningioencephalitis. These diseases are expensive to diagnose and treat and often carry a guarded or poor prognosis. Fortunately, they are a rare cause of hearing loss.
Deafness in dogs can have a variety of causes and treatments. Many cases are due to old age and treatment is neither needed nor effective. However, it is prudent to rule out other conditions that may cause hearing loss. Many of them can be treated successfully and your pet will not have to go through life being deaf.
Dr. Teresa Garden is chief veterinarian/ owner of Animal Health & Healing, a full-service holistic and conventional veterinary practice in the Maplewood/Richmond Heights area. 314-781-1738. www.AnimalHealthandHealing.com.