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What is feline hypertrophic cardiomyopathy? 

Feline hypertrophic cardiomyopathy, the most common type of heart disease in cats, causes the heart muscle to thicken and decreases the heart’s efficiency. Some cats show no sign of illness, especially early in the disease, which can lead to congestive heart failure.

What causes feline hypertrophic cardiomyopathy?

The cause of feline hypertrophic cardiomyopathy is unknown, although certain breeds of cats appear to be predisposed. Middle-aged male cats may be more commonly affected.

What are the signs of feline hypertrophic cardiomyopathy?

Signs of feline hypertrophic cardiomyopathy can vary from no symptoms to lethargy and rapid or labored breathing. Other signs can include sudden weakness, collapsing episodes, and sudden death due to disturbances in heart rhythm.

In some cases, signs of left-sided congestive heart failure, including fluid accumulation in the lung, may occur. These signs include lethargy, decreased activity level, rapid and/or labored breathing, and possibly open mouth breathing with excitement or exercise. Sometimes left and right-sided congestive heart failure develops with fluid accumulation inside the chest or abdominal cavity, causing greater respiratory effort and abdominal distention.

Once fluid accumulations have occurred, clinical heart failure is present, and aggressive medical therapy should be sought.

In some cats with a very large heart chamber, a blood clot may form and if it enters the circulation may cause weakness or paralysis (usually of the rear legs).

How is feline hypertrophic cardiomyopathy diagnosed?

A physical examination by a veterinarian may reveal a heart murmur, abnormal heart and lung sounds, or irregularities in heart rhythm that can lead to a suspected diagnosis of the disease. Chest X-rays, electrocardiograms, and echocardiograms are often used to confirm a diagnosis and determine severity.

A routine physical exam and one or more of these tests may be recommended every six months to one year to look for any progression of disease in cats without clinical signs.

How is feline hypertrophic cardiomyopathy treated?

Treatments for feline hypertrophic cardiomyopathy vary depending on the severity of the disease in the patient.

Asymptomatic cats may not need medical therapy, but routine reevaluations will often be recommended. Other cats will need medications to slow the heart rate and promote relaxation of the pumping chambers (ventricles). If arrhythmias or congestive heart failure signs are present, additional medications may be required.

Since this disease can be progressive, medications and dosage may change with time. Therapy is always tailored to the needs of the individual patient.

What should I do if my cat has or is showing symptoms of feline hypertrophic cardiomyopathy?

If your animal is showing symptoms of feline hypertrophic cardiomyopathy, contact your veterinarian or the WSU Veterinary Teaching Hospital at 509-335-0711. If your cat has already been diagnosed with the disease, our cardiology team can help to create the best treatment plan for your pet.


This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.

Image of the computer screen on a heart monitor.

What is dilated cardiomyopathy in dogs?

Just like humans, dogs can get a form of heart disease called dilated cardiomyopathy, which causes weakened heart contractions and poor pumping ability. As the disease progresses, the heart chambers become enlarged, one or more valves may leak, and signs of congestive heart failure develop.

What causes dilated cardiomyopathy in dogs?

The cause of dilated cardiomyopathy is unclear in most cases, but certain breeds appear to have an inherited predisposition. Large dog breeds are most often affected, although it also occurs in some smaller breeds, such as cocker spaniels.

Occasionally, dilated cardiomyopathy-like heart muscle dysfunction develops secondary to an identifiable cause such as a toxin or an infection. In contrast to people, heart muscle dysfunction in dogs and cats is almost never the result of chronic coronary artery disease, or heart attacks.

What are the signs of dilated cardiomyopathy?

Early in the disease process, there may be no detectable clinical signs, or the pet may show reduced exercise tolerance. In some cases, a physical examination by a veterinarian can detect abnormal heart sounds and irregular heart rhythm as the disease progresses.

As the heart’s pumping ability worsens, blood pressure starts to increase in the veins behind one or both sides of the heart. Lung congestion and fluid accumulation, or edema, often develop behind the left ventricle/atrium. Fluid also may accumulate in the abdomen or around the lungs if the right side of the heart is also diseased. When these symptoms occur, heart failure is present. Weakness, fainting episodes, and sudden death can result from heart rhythm disturbances.

What are the signs of heart failure in dogs?

Dogs with heart failure caused by dilated cardiomyopathy often show signs of left-sided congestive failure, including reduced exercise ability, tiring quickly, increased breathing rate or effort for the level of their activity, excess panting, and cough (especially with activity).

Sometimes the cough seems soft as if the dog is clearing its throat. Poor heart pumping ability and arrhythmias can cause episodes of sudden weakness, fainting, or sudden death. Some dogs with dilated cardiomyopathy experience abdominal enlargement or heavy breathing because of fluid accumulation in the abdomen or chest.

More advanced signs of heart failure can include labored breathing, reluctance to lie down, inability to rest comfortably, worsened cough, reduced activity, loss of appetite, and collapse.

Signs of severe heart failure may seem to develop quickly with dilated cardiomyopathy, but the development of underlying heart muscle abnormalities and progression to overt heart failure probably takes months to years.

How is dilated cardiomyopathy diagnosed?

A cardiac exam by a veterinarian can detect abnormal heart sounds and many signs of heart failure. Usually, chest radiographs (X-rays), an electrocardiogram (ECG), and an echocardiogram are performed to confirm a suspected diagnosis and to assess severity.

Echocardiography can be used to screen for early dilated cardiomyopathy in breeds with a higher incidence of the disease. Resting and 24-hour (Holter) ECGs are sometimes used as screening tests for the frequent arrhythmias that usually accompany dilated cardiomyopathy in some breeds, especially boxers and Doberman pinchers.

What treatments are available for dogs with dilated cardiomyopathy?

Asymptomatic cases of dilated cardiomyopathy may be treated with medications to slow the progression of the changes leading to heart failure and as symptoms advance. Since the disease is irreversible and heart failure tends to be progressive, medications and dosages usually must be increased over time.

What should I do if my dog is showing signs of dilated cardiomyopathy? 

If your dog is showing any symptoms of dilated cardiomyopathy, you should immediately contact your veterinarian or WSU’s Veterinary Teaching Hospital at 509-335-0711.


This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.

By Dr. Ryan Baumwart & Dr. O. Lynne Nelson

Many dog owners have switched their pets to grain-free, exotic-ingredient, vegetarian, vegan, or home-prepared diets over the past decade. The trend toward these “boutique diets,” however, has coincided with an increase in reports of dogs with dilated cardiomyopathy, the most common cause of heart failure in certain large breed dogs.

What is dilated cardiomyopathy?


Dilated cardiomyopathy is a disease of the heart muscle that results in weakened contractions and poor pumping ability. As the disease progresses, the heart chambers become enlarged, valves may leak, and signs of congestive heart failure develop. While the disease is not always severe enough to cause symptoms, in other cases it can be life-threatening or even fatal due to an irregular heartbeat and congestive heart failure. Read more about dilated cardiomyopathy.
Historically, dilated cardiomyopathy was primarily seen in breeds known to have a genetic predisposition to the disease, but in recent years the U.S. Food and Drug Administration reported an increase in the number of cases in other breeds. In many of the cases, the affected animals were being fed “boutique diets.” The FDA alerted the public to the issue in 2018, and since then the agency and veterinary researchers have been investing the role of diet in the increased reports.

What we know

There has historically been evidence of diet-responsive dilated cardiomyopathy in some breeds (golden retrievers, cocker spaniels, but the incidence in these breeds has appeared to increase when eating grain-free, vegetarian/vegan, or exotic-ingredient foods. In other cases, the breeds of dogs developing dilated cardiomyopathy appear unusual, meaning the dog does not have a breed history of an inherited type of the disease, or the dog may be young.

Recent studies have identified differences in blood metabolites of dogs eating some boutique diets compared to standard diets, suggesting that dogs’ bodies may process boutique diets differently.

Taurine deficiency may be a factor in some breeds (those listed above), but it is unclear whether it is a cause or merely an association with yet unknown other dietary components.
Dogs with dilated cardiomyopathy that have been eating the diets described above may reverse the condition if it is caught early or if they respond favorably to a change in diet.

What we recommend

If your dog does not have a medical condition requiring alterations in specific dietary ingredients, we recommend feeding a diet made by a well-established manufacturer that contains standard ingredients and has a record of long-term nutritional research.

If your dog has been diagnosed with dilated cardiomyopathy and is eating a boutique-type diet, we recommend changing the diet and measuring whole blood and plasma taurine levels if the breed is known to be taurine sensitive.

  • If taurine levels are low or on the low end of the normal range, dietary supplementation of taurine should be added.
  • Follow-up echocardiography should be performed in 3, 6, and 12 months to assess for improvement in heart function after diet change.
  • Screening echocardiography for dilated cardiomyopathy should be performed in all dogs of the same household eating the non-standard diet.

If your dog has a medical condition that requires a non-standard diet, we suggest a diet made by a well-established manufacturer that has undergone extensive Association of American Feed Control Officials (AAFCO) feeding trials. Your veterinarian can help you choose an appropriate diet for your dog’s medical condition.

Owners of dogs with possible diet-associated dilated cardiomyopathy should save samples (and product labels) of all dietary components they are currently feeding, including the main food, treats, chews, and supplements.

With complete diet information in hand, the veterinarian or owner should report the case to the FDA, which can be done either online or by telephone, as this will help the agency identify possible underlying causes as quickly as possible.

WSU veterinary cardiologists Ryan Baumwart, DVM, ACVIM-CA and O. Lynne Nelson, DVM, ACVIM-CA, IM are board-certified in companion animal cardiology.


This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.

Effect of Gabapentin on Cardiovascular Parameters in Cats

Gabapentin is an oral medication commonly given to cats for sedation or prior to veterinary visits to reduce their anxiety. While there are currently no known side effects in cats, this medication does tend to lower their heart rates, which can be detrimental to cats with heart conditions.

The purpose of this study is to evaluate the effect of gabapentin on feline heart function. If our study finds that gabapentin affects the function of normal cats significantly, judicious use of this medication will be recommended for cats with known or suspected cardiac disease.

Benefits

Cats in this study will receive a physical examination, two blood pressure checks, two echocardiograms and two electrocardiograms (ECG). The approximate value for these procedures is $866.00.

Enrollment Requirements

This study is being conducted in clinically healthy cats between 1 and 7 years of age and at least 8.8 pounds. Enrolled cats cannot be on any medications other than heartworm, flea and tick preventatives. Successful candidates for this study must be reasonably comfortable with veterinary visits and amenable to receiving oral medication.

Treatment Methods

There are three appointments necessary for this study, spanning approximately three weeks:

Study Screening: At this appointment, we will do a physical examination and very brief echocardiogram to make sure your cat qualifies for the study. If your cat qualifies, we will send you home with study instructions and medication (either gabapentin or a placebo).

Study Appointment 1: 1-2 hours prior to arriving for this appointment, you will give your cat the study medication dose. At this appointment, we will measure your cat’s blood pressure and do an echocardiogram and an ECG. At the end of this appointment, we will send you home with study medication (whichever medication your cat did not receive the first time).

Study Appointment 2: 1-2 hours prior to arriving for this appointment, you will give your cat the study medication dose. At this appointment, we will measure your cat’s blood pressure and do an echocardiogram and an ECG. At the end of this appointment, your cat will have completed the study.
This is a double-blind study so you and the investigators will not know which medication your cat is receiving for each appointment. Cats will be randomized to receive either gabapentin or the placebo first and will receive the opposite study medication at the second study appointment.

Owner Responsibilities

Owners are responsible for bringing their cat to the WSU VTH for the three study appointments. To be eligible for this study, owners must be able to a) give their cat pills at home and b) carefully follow a written study timeline.

Contact Information

Valorie Wiss, Clinical Studies Coordinator
509-335-0789
v.wiss@wsu.edu