Visiting Veterinarian

Lesley Segal-Pallas with daughter Naomi
Lesley Segal-Pallas with daughter Naomi and hearing-impaired dog Kramer. Naomi is holding Ella and the other cat, Winny, can be seen behind. Photo by Lynn Christoffers

Hard-of-hearing dogs

By Michele Gerhard Jasny V.M.D. - November 8, 2007

When Lesley Segal-Pallas and her daughter Naomi decided they were ready to get a dog, they weren't in complete agreement about the details. Mom wanted an adult, small- to medium-sized poodle. Poodles were smart, she figured, and didn't shed too much. An adult dog would be housebroken and well trained. Naomi had a different idea. She didn't want a frou-frou dog. She was thinking something big and young and shaggy.

When they arrived at the MSPCA, they found, to their delight, a dog that was an exact compromise of their divergent wish lists. Dubbed "Kramer" because of his wild, just-fell-out-of-bed, Seinfeld-esque coat, the shelter staff guessed he was a poodle-terrier cross, or maybe a little Bichon... or was that dachshund? Whatever.

Estimated to be around four years old, Kramer was found as a stray in Methuen, already neutered and housebroken. He obviously had been someone's pet sometime, but no one had claimed him. He weighed in at a reasonable 25 pounds, not too big, not too small, and although he was adorable, no one would call him frou-frou. "There's just one thing we should mention," the MSPCA staff volunteered. "We think he has some hearing loss."

Deafness in dogs can be classified in several ways. It can be inherited or acquired, congenital or late onset. Inherited deafness is due to a chromosomal abnormality and is usually congenital, in other words, present from birth. There are many breeds that carry such genes, one of the better-known being Dalmatians. The genetics of transmission of canine deafness is not well understood but in many cases appears to be linked to coat color. Harlequin Great Danes, merle colored collies, white dogs of many breeds, and those with blue eyes, have an increased incidence of inherited deafness. Cats also inherit a white coat, blue eye associated deafness. Not all white animals or all those with blue eyes are deaf but they do have a statistically higher risk. Acquired deafness is typically of later onset and can be the result of many different causes: infections, trauma, noise, drug toxicity, and aging, to name a few. Deafness can also be classified as conductive or sensorineural. In conductive deafness, pathology in the outer or middle ear prevents sound from being transmitted to the inner ear and brain. Ear infections, tumors in the canal, or closure of the canal from surgery are examples. Sensorineural deafness is the result of a malfunction of the inner ear, auditory nerve, or the brain. Inherited and age-related deafness are both usually sensorineural.

Leslie and Naomi were not fazed by the idea of adopting a hearing-impaired dog. In fact, it seemed fitting. Lesley is an audiologist and her practice, Vineyard Audiology, is dedicated to evaluating human hearing and auditory-related concerns. She works with people of all ages from newborn babies to centagenarians, why not a dog? They happily took Kramer home. Trying to assess the degree of his impairment, Lesley and Naomi experimented. They yelled, called, tried high-pitched dog whistles, and low-pitched sounds. Kramer responded to vibrations, so they stomped on the floor to get his attention. He sensed the rumble of motorcycles zooming by. Once, while watching a scary movie, mother and daughter simultaneously let out loud, shrill shrieks. Kramer reacted. Lesley felt that Kramer could hear a very limited range of very high-pitched sounds if they were extremely loud but otherwise he was profoundly deaf. Was there a more exact, scientific way to assess him beyond motorcycles and horror flicks?

Determining deafness

The standard method employed by veterinary specialists to assess hearing in dogs is the Brainstem Auditory-Evoked Response (BAER). Electrodes are placed on the dog's head and a specific noise is made, usually a clicking sound. The electrical activity in the brain is recorded. If the auditory stimulus is getting through to the brain, it should respond in a consistent way, even if Kramer does not visibly react. Few owners go to the lengths of BAER testing but it is always worth having your regular veterinarian examine your dog. Something as simple as a polyp in the ear canal or a bad infection can interfere with hearing. Such things can often be treated and resolved. Sensorineural deafness is another story. There is no known treatment.

What about hearing aids? For most sensorineural deafness, a traditional hearing aid will not help but veterinarians have tried over the years to make dog-friendly devices for those animals where it might be useful. The problem has been getting the dog to tolerate it. All too often, the expensive aid was lost, or worse, eaten by the patient. Hearing aid batteries can cause serious problems if ingested. Most of them manage to pass, but if the button battery gets lodged in the gastrointestinal tract, especially the esophagus, serious consequences can ensue. There is even a National Button Battery Ingestion Hotline (mostly to deal with children, who swallow these things too.) Theoretically, a cochlear implant could be used in dogs but no one is routinely doing these due to the expense.

Although Lesley herself works with hearing aids, in her opinion such a device would not improve Kramer's quality of life. "I think the amplification would startle him," she says. Instead they use hand signals. Kramer knows "sit" (point to the ground), "no" (a horizontal sweep of the hand), and "good boy" (lots of clapping.) "He's not very good at staying," Lesley admits "so we gave up on that signal." When asked what the biggest challenge is, Lesley says "the strange looks I get from people at the dog park."

"Why is he on a leash?" they ask. Some encourage her to let him loose. She tried it a few times. The first time, Kramer stayed close. The second time, he wandered. The third time, he ran off.

"That was enough for us to realize it wasn't safe," Lesley confides. "He doesn't hear signals from other dogs. Maybe because he's part terrier, he totally gets into what he's sniffing and he's oblivious. Other dogs come up to him. He doesn't notice, he doesn't respond to them. He's in Kramer La-La Land. He has been attacked by other dogs more than once." Lesley feels that Kramer may well have been hearing-impaired since birth, based on his level of unawareness to other dogs and his environment...and based on the timber of his voice.

"He has a 'deaf' quality to his bark," she explains. "Though he doesn't bark much," she continues fondly, " Except at rocks...big rocks."

What if the pet you already have seems to be going deaf? Lesley puts on her audiologist's hat. "Test what your dog responds to. High pitch and low pitch. Bang a toy drum. Clank pots. Try it when they are asleep, and make sure you are not in their visual range as they may respond to what they are seeing, rather than hearing."

As to the fancy testing? Lesley sums it up, "If you were to determine your dog had a hearing loss, it wouldn't change your relationship with your dog." Lesley and Naomi adore Kramer. He sleeps on Naomi's bed, right by her head.

"He's gentle, he's sweet, he loves people. Personally, I believe rescue animals are the way to go. It's so important." Lesley pauses, then adds. "And between you and me, his deafness just adds to his character. I would never hesitate to adopt another deaf animal. Without a doubt, he's the sweetest dog in the world."