What Do Pongo and Perdita Have to Do with Deafness in Dogs and Cats?

August 6, 2014

Image from 101 DalmatiansThe image on the right, is of Pongo, Perdita and their family, the iconic Dalmatians from the classic Disney movie, 101 Dalmatians. Yes, it is one of my childhood favorites, but the image is here because today I am writing about hearing loss in dogs and cats, and Dalmatians are the breed most commonly associated with an inherited form of deafness. Inherited deafness is just one type of hearing loss. Medically, veterinarians use several different classification schemes to categorize hearing loss in pets.

Inherited or Acquired Deafness
Inherited means hearing loss is due to abnormalities in the genetic material coding for hearing. In dogs, inherited deafness is associated with white haircoats, piebald (spotted) haircoats like the Dalmatian, or merle (dappled) haircoats like the Australian Shepherd. Most inherited hearing loss becomes obvious at just a few weeks of age. Acquired deafness occurs because a disease or medication destroys hearing function or because of normal aging.

Sensorineural or Conductive
While these words may not be familiar to many of my readers, the explanation of the words is quite easy to understand. In order for sound to be conducted from the ear to the brain, sound must get into the ears. Either a bad ear infection (a really common cause of hearing loss in dogs and cats) or a tumor or the ear canal (a much less common cause of hearing loss) can obstruct the ear canal. Both conditions result in conductive deafness. Sensorineural deafness results from dysfunction of the hearing structures of the ear, nerve damage to the auditory nerve or a problem in the brain’s ability to perceive sound. Sensorineural deafness is the common form of hearing loss in older animals.

Congenital or Late Onset
Congenital deafness is a condition present at birth. The majority of white cats with two blue eyes are born deaf. Less than half of white cats with one blue eye are deaf and they are usually deaf on the side with the blue eye. If we use all the classification schemes together, white cats with blue eyes have inherited congenital sensorineural deafness.

If you have an older dog who has had multiple bad ear infections and can no longer hear well, he probably has acquired late onset conductive deafness.

Dog with BAER electrodes attached

Dog with BAER electrodes attached

Hearing Tests in Pets
The Animal Medical Center’s Neurology Service uses a test called the brainstem auditory evoked response (BAER) to diagnose hearing loss in pets. The BAER machine measures brainwaves in response sound using electrodes attached to the skin.

Alterations in brainwaves indicate conductive or sensorineural deafness. BAER can be used to identify congenital deafness in puppies and kittens and exclude them from breeding programs.

Treatments for Deafness in Pets
If hearing loss is caused by an ear infection, treatment may restore hearing. Pet owners often ask about hearing aids for dogs. For pets with congenital deafness like the Dalmatian or white, blue-eyed cats, hearing aids will be of no benefit as hearing aids amplify sound, but this type of hearing loss cannot detect any sound at all, even really loud sounds. The use of hearing aids has been tried in dogs with limited success. Dogs are not always cooperative with devices placed in their ears. Many dogs (and cats) acclimate to their hearing loss. Since smell is a dog’s most highly developed sense, deaf dogs and cats can function well as indoor pets.

Further Reading


Is My Pet Sick or Just Getting Older?

November 15, 2013
senior dog

Photo: seniordogcareproducts.com

As our pets get older, we expect them to slow down as part of the aging process, but how much slowing down is too much? What signs should pet owners watch out for in their senior pets that may suggest there is more going on than simply normal aging?

What qualifies a pet as a senior pet?
Senior pets can loosely be defined as those in the last 25% of their anticipated lifespan for their species and breed. For example, a cat expected to live 15 years would be considered senior at 11 years of age. What that means to dog and cat owners is 9-11 years of age is the start of your pet’s senior years. One notable exception is giant breeds of dogs who are considered senior a year or two earlier.

Slow motion
Many pet owners assume their pet is slowing down because it is older. Since aging is associated with a variety of illnesses, if you have a senior pet who seems to be slowing down, take him for a complete physical examination. Your pet can’t tell you their joints hurt from arthritis, but your veterinarian can. Never give your dog or cat your arthritis medication as these drugs are extremely toxic to pets. There are medications that can help make your arthritic pet more comfortable and kick their activity level back up a notch.

Forgetfulness
Another behavior change incorrectly attributed to aging is loss of housebreaking/litterbox use. Older cats are especially prone to developing kidney problems, and the accompanying increase in urine production. Couple an increase in urine production with creaky joints that don’t move so well anymore and your cat may act as if he has forgotten where to find the litter box. Placing litterboxes conveniently near your cat’s favorite perch will help overcome this problem. Some creaky cats can no longer climb over the edge of the litter box and will “go” right outside the litterbox. Substituting a box with lower sides or a cut out for easy entry will often resolve this situation. Diabetes and urinary tract infections will also cause what appears to be a loss of housebreaking. All of these reasons may contribute to a lack of litter box use, but the reason may be as simple as not changing the litter often enough to your cat’s liking.

Cognitive dysfunction syndrome
A syndrome is a collection of clinical signs that commonly occur together. Once your veterinarian has determined an illness is not causing your pet to slow down, cognitive dysfunction syndrome (CDS) will be considered. CDS in a decline in brain function in the aging dog exemplified by behavior changes. Dogs with CDS may stand in one place more often, greet the owners less often and have accidents in the house. At the recent Zoobiquity 3 Conference in New York City, Dr. Chad West, one of The AMC’s board certified neurologists, discussed a case of CDS in a dog. The MRI findings in the dog were strikingly similar to the second most common cause of dementia in humans, vascular dementia.

Keeping your pets young
Sadly, there is no fountain of youth for either you or your pet, but there are things pet owners can do to keep their favorite fur baby around as long as possible.

  • Don’t assume changes in your pet’s behavior, activity or appetite are “just old age.” Bring these changes to the attention of your veterinarian.
  • Take your pet for regular veterinary check-ups. The current guidelines recommend annual visits for younger pets and more frequent visits as your pet ages. Early detection of disease can mean all the difference in extending the life of your pet.
  • Keep your pet mentally and physically active. Use feeding toys to challenge your pet to “hunt” for her food. Consider low impact exercises for your dog, such as swimming. Exercise your dog or cat on a regular basis.

Avoiding the Knife: Preventing Pet Surgeries

April 11, 2013

At The Animal Medical Center, our board certified surgeons and neurologists perform approximately 1,500 surgeries each year. A recently released pet insurance study completed in 2012 listed the top ten surgery claims for both dogs and cats:

Top-10-Canine-Conditions-large

Survey attributed to VPI Pet Insurance 2012

Since none of us want our pets to be subjected to the difficulties most surgeries pose, I will devote this blog to suggestions on how to avoid some of the most common canine and feline surgeries.

Tooth extractions

Topping the surgery list for cats and coming in at number three for dogs were tooth extractions. Keeping your pets’ teeth healthy means daily brushing and annual dental cleanings. The American Veterinary Dental College website provides good information about home dental care in dogs and cats. Remember, doggy breath often means periodontal disease, so if your pet has smelly breath, see your veterinarian for treatment before extractions become necessary.

Skin abscess, inflammation and pressure ulcers

This list of skin conditions ranks number two as a reason for surgery in both dogs and cats. Pressure ulcers generally occur in older dogs with limited mobility. Padding, padding and more padding will help prevent pressure ulcers on their elbows and thighs. Investigate orthopedic beds for your dog and try to keep him from laying on hard surfaces like the bathroom tile floor which can aggravate pressure sores. Promote mobility in your dog through regular exercise and management of arthritis with diet and medications.

Feline bite wounds

When I was a veterinarian in a more suburban area, we treated cat bite wounds on a daily basis. Preventing cat bite injuries is as simple as keeping your cat indoors. Cat bites not only cause wounds which can become abscesses, but cat bites transmit the feline immunodeficiency virus and possibly blood parasites as well. Priceless is how I define the value of keeping your cat indoors and healthy.

Aural hematoma

The tenth most common surgery in dogs was to repair an aural (ear) hematoma. Cats can develop aural hematomas too, just not as commonly as dogs. This condition is essentially a blood blister inside the ear flap. Blood accumulates in the ear flap when your dog incessantly shakes his head or scratches her ears. Usually, the shaking and scratching is in response to an allergy or an ear infection. If you see this behavior, check inside the ear for redness or discharge. See your veterinarian immediately to treat the cause of the shaking and scratching to prevent the development of an aural hematoma.

While some surgeries are unavoidable, these are prime examples of how a visit to your veterinarian for routine preventive care can help your pet avoid surgery.


Seizures

April 26, 2012

Seizures are a frightening medical condition. Like lightning, a seizure strikes out of the blue, due to a short circuit in the brain. After a minute or two, the brain resets itself. Even though seizures commonly last a minute or two, watching your pet lose consciousness, twitch, jerk, and maybe even lose bowel and bladder control is scary. Seizures brought Ruby, a sleek black cat, to see Dr. Chad West of The Animal Medical Center’s Neurology Service.

Two years before she came to The AMC, Ruby’s primary care veterinarian diagnosed her with a seizure disorder. Treatment with an anticonvulsant medication controlled the seizures, but just prior to her visit at The AMC, the seizures became more frequent.

The cause of seizures discovered

While Ruby was not having a seizure when she arrived at The Animal Medical Center, her physical and neurological examination demonstrated that she had weakness of the left side of her body, and there was evidence that the pressure on her brain was not allowing adequate blood flow to this vital organ. The combination of Ruby’s signs represented a potentially life-threatening situation and the neurology team immediately performed an MRI to evaluate Ruby’s brain for the cause of her issues and to develop the best therapeutic plan.

This panel from Ruby’s MRI shows the large areas of water on the brain marked with red stars.

Water on the brain

Ruby’s diagnosis was obstructive hydrocephalus (high pressure water on the brain) associated with head trauma when Ruby was a youngster. In addition to the anticonvulsant medication that Ruby had been taking, steroid treatment was instituted to decrease the pressure on Ruby’s brain and to help her have a normal quality of life, despite decreased cerebral blood flow. The decision was made to also add a second anticonvulsant drug, Keppra, to ensure better seizure control.

Trying a new drug

Keppra is a relatively new anticonvulsant medication, and at the time of Ruby’s presentation and diagnosis, very few cats in the world had been treated with Keppra to help with seizure control. In addition to being an extremely safe medication with limited side effects, Keppra has the ability to protect the brain during times when there is abnormal blood flow.

Treating cats with anticonvulsant medications can be tricky. Veterinary neurologists focus on seizure control without losing sight of the cat’s quality of life. Their goal is to have them behave normally without having seizures. Generally, attaining the appropriate balance takes a few minor adjustments in dose. Some anticonvulsant medications also require regular blood test monitoring to ensure that other organs are not being harmed by the anticonvulsant drugs.

The high dosage of phenobarbital, Ruby’s original anticonvulsant medication, put her at risk for developing liver failure. The addition of Keppra, coupled with lowering the pressure on Ruby’s brain, allowed reductions in her phenobarbital dosage to a safer level and improved her overall quality of life.

The outlook

Even though Ruby will require life-long medications, she has done fabulously well in the four years since she first came to The AMC and her neurologists expect her to continue to do well.

The successful treatment of Ruby is an excellent example of why finding the right specialist is critical when your pet has a serious disease. The experience, knowledge and technology of The AMC neurology team allowed an accurate diagnosis and novel treatment resulting in an excellent outcome.


Sidney the Cat Goes “Red” to Educate Owners About Feline Heart Disease

February 27, 2012

February is American Heart Month. According to the Centers for Disease Control, the most common form of heart disease in humans is coronary artery disease. This disease causes the blood vessels supplying the heart muscle to become blocked, resulting in a heart attack. To raise awareness of heart disease in women, the Go Red for Women campaign works to wipe out heart disease and stroke in women.

Both dogs and cats suffer from heart disease, but neither have heart attacks like we do. Dogs most commonly develop thickened heart valves. The thickening prevents normal value function. Although he is a cat, Sidney, a patient of The Animal Medical Center’s Cardiology Service, has agreed to “Go Red “ and be the AMC’s spokescat for feline heart disease.

Meet Sidney. In addition to being a handsome, 10-year-old white cat with black trim, Sidney is a tough nut to crack from a medical perspective. Before Christmas, Sidney started having episodes of falling over without losing consciousness and sometimes he would curl his feet under himself and act woozy.

First steps

Sidney’s owner took him to his regular veterinarian, whose first step was to obtain routine blood tests looking for metabolic causes of episodes like an overactive thyroid gland, low blood sugar, or anemia. But the answer was not going to come easily; the tests were normal.

A neurology c consultation

Was it his brain malfunctioning causing a strange kind of seizure? Sidney first came to The AMC and saw board certified neurologist, Dr. Chad West.

After assessing Sidney, Dr. West determined Sydney’s problem was not neurological. But he did detect an abnormal heart rhythm and a murmur. Because episodes in cats can be caused by an abnormal heart, a cardiac evaluation was recommended for Sidney.

Finally an answer

Sidney came back to The AMC to see board certified cardiologist, Dr. Philip Fox. An electrocardiogram (EKG) showed enlargement of the right heart and he confirmed the abnormal heart rhythm and murmur. Dr. Fox then used a non-invasive echocardiogram to evaluate Sidney’s heart and found the muscle of the heart walls to be thickened. View Sidney’s echocardiogram:

The diagnosis was hypertrophic cardiomyopathy (HCM), or an abnormally thickened heart muscle. The thick muscle prevents the heart from normally filling with blood and is likely the cause of Sidney’s collapsing episodes. Enalapril, an ACE inhibitor, was prescribed for its beneficial effects and high level of safety in cats with heart disease, but if it does not correct Sidney’s collapsing episodes, different medications will be prescribed.

Feline heart disease

The most common disorders of the feline heart are abnormalities of the heart muscle itself. Thick heart muscles, like Sidney’s, are the most common; less frequently veterinary cardiologists diagnose thin, flabby heart muscles. Either form can lead to heart failure which is a backup of fluid into the lungs due to decreased heart muscle function.

Tips for the cat owner

Like Sidney, cats with feline cardiomyopathy can be successfully treated.

Early treatment of feline heart disease is critical, since cats without heart failure live longer than those developing heart failure. If your veterinarian detects a heart murmur or abnormal heart rhythm during your cat’s annual physical examination, ask if a further evaluation by a veterinary cardiologist is required.

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This may also be found in the Tales from the Pet Clinic blog on WebMD.com.

For over a century, The Animal Medical Center has been a national leader in animal health care, known for its expertise, innovation and success in providing routine, specialty and emergency medical care for companion animals. Thanks in part to the enduring generosity of donors, The AMC is also known for its outstanding teaching, research and compassionate community funds. Please help us to continue these efforts. Send your contribution to: The Animal Medical Center, 510 East 62nd Street, New York, NY 10065. For more information, visit www.amcny.org. To make an appointment, please call 212.838.7053.


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