Can You Hear Me Meow?

domino

Oh, hey there! Sorry, I didn’t hear you visit my blog. My name is Domino, and I have been deaf as long as I can remember. It’s okay, don’t feel sad or take pity on me. I’m as happy as can be. Where you hear sounds, I hear the sweet serenity of silence. My world is quiet, but I’m not alone, because I have my humans to take care of me and help me along the way. It can be challenging at times being a small kitten in a not so loud, but still large world. I like to be given advanced warnings when being approached. Since I am deaf, my other senses are heightened. Therefore, I can feel and see a lot more than the typical cat that relies on hearing. In addition, it’s best I don’t go outside because I can’t hear an oncoming car…yikes! Thankfully, I’m safe and sound inside. Like the renowned and fellow deaf companion Helen Keller once said, “Everything has its wonders, even darkness and silence, and I learn, whatever state I may be in, therein to be content.” That’s what I am trying to find…a place where I can be me—an adorably cute kitten who loves attention who just happens to have a hard time hearing. I may not know what the fox says…but I don’t think anyone really does because it’s an ancient mystery anyway.  

I’m not into big technical health terms, but thankfully my mom can explain my hearing loss to you. This is because my mom is also my veterinarian. Mom….Mom…Mom!!!

Dr. Alyssa Auer: Aww, Domino you really are the cutest cat around.

When you look at Domino’s ears there’s nothing obviously wrong with them, and because he’s a kitten the cause of his deafness is considered congenital, a word that means it happened at birth. In order to solve this puzzle, we have to understand where and why hearing impairment can happen. Sound is funneled by the outer ear travelling through the ear canal to vibrating the ear drum. Resonating on the other side of the ear drum, there are three tiny bones (anvil, stirrup, and hammer) in the middle ear which transmits these vibrations into the inner ear—called the cochlea—that is lined with tiny sensitive hairs. The motions of these tiny sensitive hairs forms a nerve impulse—an impulse that travels to the brain and is experienced as sound.

The transmission at any point in this chain reaction can be damaged. In Domino’s case, it could be the three tiny bones, the cochlea, or the nerve that didn’t form correctly. Congenital can be either genetic (DNA) or developmental causes. An example of a developmental cause is if the mother was given a medicine, such as gentamycin, while she was pregnant. Then, the middle and inner ear structures don’t form correctly. A genetic example is cats with white coats and blue eyes. Just like cats with white coats, dogs with dilute, or coats with more white, are more likely to be deaf. The Dalmation is one breed of dogs that has a high number of genetically linked deafness. White animals are more likely to be deaf because cells called melanocytes keep the two salts sodium and potassium in the right ratio, or balance, in the inner ear. Without these, cells in dogs and cats ears don’t work properly and they are deaf. These same melanocytes are the cells that make pigment, or color, in the fur and skin. Therefore, the lack of genetic code for melanocytes makes them both deaf and white coated.

Animals of any age can have chronic (long term) ear infections that cause scar tissue to form in the canal, and can damage or rupture the ear drum. The natural process of aging can cause fusion, or anchylosis, of the three tiny hearing bones. Loud noises can cause trauma to the ear drum or inner ear. It’s true that trauma such as getting hit by a car can also cause hearing loss in animals, but it’s considered that trauma that severe causes other brain damage as well. Inner ear damage to the tiny sensitive hairs in the cochlea can be caused by loud noises and ototoxic (ear damaging, killing cells in the ear) substances. An example of an ototoxic substance is a class of antibiotics called fluoroquinolones. Veterinarians try to avoid using these antibiotics in young animals, but sometimes these are the only antibiotics that can kill bacteria—bacteria that would otherwise kill the animal. As you will read later, animals that lose their hearing do go on to have normal lives and adapt very well.

How can you tell if your dog or cat is deaf? You can pick up on some subtle signs: their ears don’t swivel to locate noise, they look the wrong way when there’s a loud noise, you can easily sneak up on them or they are excessively startled by touch. If their inner ear is affected, then the pet’s sense of balance could be compromised. This could look like a crooked walk, or a cat may avoid jumping up to and down from high places because her balance is compromised. However, their instinct to bark or meow is not affected. Even as a deaf kitten Domino still meows, being deaf didn’t interfere with this instinct.

I could tell from the moment that I first found Domino that he is an extremely cool cat. He stays calm and collected even when a dog is going crazy next to him. It was this observation that told me something wasn’t adding up. When trying to figure out if your cat or dog is deaf at home, keep in mind that your pet can react to other stimuli. When you clap your hands, it’s the motion of your hands that alerts your pet, not the sound of the clap. Walking into a room your footsteps make vibrations. In order to do an at home test during a quiet time, get behind your pet and make a loud noise. Avoid stomping as the vibration in the floor could be what alerts your pet. Try different ranges of noises. Whistle for a high range, clap your hands for a mid-range, and beat a drum or similar object for a low range. The volume or loudness of your cues should also vary. Dogs and cats can have limited hearing ranges, or be hard of hearing and can only hear high decibel, or louder, sounds.

Just like humans, an animal can be hard of hearing and not completely deaf. It’s also possible to be deaf in only one ear, unilateral deafness, rather than being deaf in both ears, bilateral deafness. This is harder to figure out in a pet, and as a pet owner you’re more likely at home to figure out that your pet has hearing loss, but you still need your veterinarian to look them over and confirm any possible hearing loss.

When you ask your vet to check if your pet is deaf, he or she will do a thorough exam looking into the ear canal. This is to look for chronic ear infection as a possible cause. Older dogs may also have other unrelated aging changes. The only true way to diagnose deafness in a dog or cat is by the Brain stem Auditory Evoked Response, or BAER test. This test is typically performed under heavy sedation. A click stimulus from the position of the ear canal is transmitted through the ear and the electrical activity of the brain is recorded from an electrode on the scalp. The electronic activity is interpreted by a special purpose computer. Of course, this requires sophisticated equipment that is not in a general veterinary hospital. Locations where BAER tests are performed can be found at this link: BAER test sites

A question owners frequently have is whether hearing aids can be outfitted for deaf animals. The truth is that most hearing aids are sound amplifiers. Most animals born deaf are completely deaf and no amount of amplification can help this. Research at the Veterinary College of Auburn University found that not all dogs tolerate a hearing aid in their ear canal. Smaller breeds were more likely, but it was entirely up to the individual. Given the high cost of the units and the possibility that a dog will try to take them out, it’s considered unpractical. George Strain, PhD of Louisiana State University remarks that “owner(s) can empathize with a pet’s deafness, the reality is that most deaf dogs and cats give no evidence of being bothered by their deafness, and adapt quite well, relying on their other senses.”

For the owner of a deaf pet, it’s important to protect them from undetectable dangers, such as motor vehicles. These dogs and cats should be kept strictly indoors and with a fenced in backyard. As they are easily startled, family members should learn to alert the pet, especially from sleep. Dogs will reflexively bite if startled and small children should especially be protected from this. If nothing else, a dog can wear an open basket muzzle if an infant or toddler is in the family to avoid the heartbreak of a child being bitten. Deaf pets do adapt remarkably well to their condition, and rely on cues from their other senses. Deaf dogs can benefit from vibration collars to alert them when a person enters a room. Anecdotally, vibration collars have been used to train young deaf dogs for the cues to sit, stay, and come.

I found that Domino needed some extra guidance on social cues from his sister, Chloe, a 5 year old Basenji. Chloe prefers a private dining experience—she doesn’t ever like her siblings eating out of her food dish. She gave Domino the warning growl, but in his silent little world there was nothing but mouthfuls of nom-noms. In this case, he needed a bump on the butt to get out of there before real trouble would start. As a deaf kitten, his balance could have also been affected, but he’s very adept at jumping up to high places and always lands on his feet. He may not be able to hear, but he’s one resilient, and very cute, kitty.

Alyssa Auer, DVM
Stow Kent Animal Hospital & Portage Animal Clinic

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Dr. Auer

Timothy McQuait as the voice of Domino

More information can be found through the research, advice and insights of George Strain, PhD of LSU:

Deafness in Dogs and Cats

Congenital Deafness and Its Recognition

How well do dogs and other animals hear?

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