Matters of the Heart

Photo Credit: Just like us, our dogs and cats can develop heart disease. What may surprise you is that they don’t experience heart attacks (myocardial infarctions), the most common human heart health issue. This is likely because dogs and cats don’t live for multiple decades, the time needed for substantial amounts of plaque to accumulate within the coronary arteries. (They don’t smoke cigarettes either!)

Causes of heart disease in our pets

Dogs and cats can develop a variety of heart diseases. Some occur more commonly in particular sizes and breeds. Others, such as heartworm disease, affect dogs and cats of all shapes, sizes, and breeds.

The most common cardiac problems in dogs and cats include:

  • Congenital (birth) defects: This category includes faulty heart valves, wall defects between chambers of the heart, and blood vessels that are abnormally configured. These abnormalities alter normal blood flow in and around the heart.
  • Heartworm disease: In the infected dog or cat, long spaghetti-like worms set up housekeeping within the heart and arteries that supply the lungs. Left untreated, heartworms can cause both heart and lung disease.
  • Valve disease: Valves control normal blood flow in and out of the four chambers of the heart. Age-related heart valve degeneration occurs commonly, particularly in small breed dogs. The resulting “valvular insufficiency” leads to heart failure in some, but not all cases. A relatively uncommon disease that can disrupt valve function is endocarditis, a bacterial infection that develops on one or more of the heart valves.
  • Cardiomyopathy (disease of the heart muscle): The heart muscle can become too thin and flabby (dilated cardiomyopathy) or too thick and stiff (hypertrophic cardiomyopathy). Both conditions impair the normal pumping action of the heart.
  • Arrhythmias (alteration of the normal rhythm of heart beats): An abnormal heartbeat here and there causes no problem, but multiple abnormal beats can produce significant symptoms.

Warning signs of heart disease

The heart is a muscular pump responsible for circulating oxygen rich blood throughout the body. When the pump fails, not only can abnormal fluid accumulations occur within the body, the animal develops symptoms caused by decreased oxygen supply.

Early warning signs of heart disease can include:

  • Increased respiratory rate
  • Cough
  • Lethargy
  • Restlessness during sleep
  • Decreased stamina
  • Vomiting (occurs in cats)

More advanced heart disease may cause:

  • Weakness
  • Loss of appetite
  • Labored breathing
  • Distention of the abdomen with fluid
  • Blue/purple tinged tongue and gums
  • Collapse
  • Fainting
  • Sudden death
  • Sudden paralysis of the hind legs caused by a blood clot within the aorta (occurs in cats)

Diagnosis of heart disease

Tests used to confirm the diagnosis of heart disease commonly include:

  • A thorough physical examination that includes auscultation (listening to the heart and lungs with a stethoscope)
  • Blood tests including screening for heartworm disease
  • An electrocardiogram (ECG) to evaluate the rhythm of the heartbeats
  • Chest x-rays to evaluate the size of the heart and identify abnormal fluid in or around the lungs
  • An echocardiogram (an ultrasound evaluation that provides a look inside the heart) to evaluate valve function, chamber size, and the strength of heart contractions

Treatment of heart disease

While many canine and feline heart diseases are not curable, they are often very treatable. Medications are the mainstay of treatment for most types of heart disease. They are used to mobilize excess fluid accumulating in the chest, lungs, and/or abdomen. Drugs are also used to decrease the workload on the heart, enhance the strength of heart contractions, and prevent blood clots. If a heart rhythm abnormality is detected, an antiarrhythmic drug may be prescribed.

Some types of heart disease are best treated with surgery or a specialized procedure. They may involve installation of a pacemaker, repair of a defective heart valve, or correction of a birth defect.


Prevention can reap wonderful benefits when it comes to heart disease. An example is the use of medication to prevent heartworm disease in dogs and cats. A thorough physical examination performed by a veterinarian once a year (twice yearly for senior dogs and cats) is another excellent preventive measure. These exams provide a golden opportunity  for early disease detection. In many cases, the earlier heart disease is detected, the better the long-term outcome.

Questions for your veterinarian

If your four-legged best friend has heart disease, here are some key questions to ask your veterinarian.

  • What type of heart disease does my pet have?
  • How is it best treated?
  • How will I know if treatment is working?
  • What symptoms should I be watching for?
  • When should my pet be rechecked?
  • Can you refer me to a specialist? Whenever a serious disease is suspected or diagnosed, a second opinion is a good idea. Additionally, an echocardiogram and other advanced cardiac procedures require specialized equipment and skills. They are best performed by a veterinarian with extra training in cardiology, internal medicine, or radiology.

Have you ever cared for a dog or cat with heart disease? If so, what type and what was the outcome?

Wishing you and your four-legged family members good health and happiness throughout the holiday season,

Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
Become a Fan of Speaking for Spot on Facebook

Please visit to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at,, local bookstores, and your favorite online book seller.

Be Sociable, Share!

6 Comments on “Matters of the Heart

  1. An elevation of cholesterol within the bloodstream of a dog does not increase the risk of heart disease as it does in people. It can, however, be an indicator of an underlying disease process such as a hormonal imbalance, a kidney disorder or liver disease. I would encourage having further discussion about this with your veterinarian. The first step might be to recheck the value after your dog has fasted for 12 hours.

  2. My vet said that the degree of elevated cholesterol is not a worry for dogs. True? My dog has elevated cholesterol.

  3. Yes, our Lhasa Apso, Dakota, was diagnosed with mitral valve disease at around age 14. His only symptom was a slight cough, and fortunately his symptoms occurred very close to his 6 month routine geriatric exam. The condition was easily treated with medication. He lived a quality life until nearly 17 years of age, and his mitral valve disease, and subsequent renal disease, were treated and managed the last years of his life. We were fortunate to enjoy him for so long as a member of our family.

  4. I’ve had Cavalier King Charles Spaniels now for nearly 32 years, so I know all about early onset mitral valve disease, as it is highly prevalent in Cavaliers. Over the years, I’ve owned 9 Cavaliers and only one never developed MVD. I’ve had two Cavaliers die from it; the others have had murmurs but were asymptomatic and never on meds. They died of old age, cancer, and one from what we think was a thrown blood clot.

    If one is considering buying a Cavalier, they need to educate themselves about Cavaliers and MVD. A very large scale heart study was done many years ago by vets at U of Edinburgh, U of Penn, and a geneticist in Sweden. It is still the gold standard of studies. The results of that study led these doctors to develop a breeding protocol for Cavaliers in order to raise the age of onset of MVD. It is a polygenic trait (multiple genes) so cannot be gotten rid of. The Protocol recommends the following:

    1-Both sire and dam need to be heart clear at age 2 1/2 before being bred.
    2-Both their sires and dams must be heart clear at age 5.
    3-If the status of the sire and dam is not known, then a bitch or dog must wait till age 5 and be clear before being bred.

    ALL clearances MUST be done by a board certified veterinary cardiologist!!!!

    Unfortunately, very few breeders follow the entire Protocol. Most follow the 2 1/2 and clear part, but not that of the sire and dam of the breeding pair.

    Clearances for MVD (and diagnosis of pets) is best done by a cardiologist using auscultation. A heart x-ray should be done when the Cavalier is young to use as a baseline for x-rays done after the dog develops MVD for comparison. An echo is usually only necessary to absolutely confirm the diagnosis if the Cavalier is a valuable breeding animal – one would not spay/neuter based solely on auscultation.

    Auscultation was chosen as the means of diagnosis as it is sensitive enough to properly diagnose MVD but not so sensitive to remove too many dogs from the gene pool. It is NOT necessary for a pet.

    So, where to find a board certified veterinary cardiologist? In a major metropolitan clinic, they may well be in a specialist clinic, but will not be found in smaller cities. An internist “MAY” be able to diagnose MVD, but the CKCSC still recommends a cardiologist. Your local vet will not hear low-grade murmurs in most cases.

    A great resource to find a cardiologist (and more about MVD in Cavaliers) is the web site . This site was put together by a longtime Cavalier pet owner and is very well researched.

    Local kennel clubs regularly schedule heart clinics where a board certified cardiologist can check your dog. The above web site lists those as well! Eye clinics are often held in conjunction with the heart clinics.

    If one lives near a vet school, there is often a cardiologist who will see dogs at the small animal clinic. If your dogs is not doing well being treated by your vet, TAKE THE DOG TO THE NEAREST VET SCHOOL to see a cardiologist. They have far more experience than even a local specialist clinic.

    MVD is often asymptomatic and causes the dog little trouble. A study was done a N Carolina State Vet School about medicating BEFORE symptoms and found that it did not slow the progress of the disease and is not recommended.

    Typically the drugs used for symptomatic dogs are Lasix (a diuretic), and enalapril (an ACE-inhibitor). Dogs in end-stage MVD failure are often given Pimobenden (Vetmedin), which has often been a miracle drug for many a Cavalier in congestive heart failure.

    The author of the web site quoted, is a great believer in holistic medicine and strongly recommends many supplements. There have been no studies on their benefit and the is a truly personal choice made best between you and the cardiologist.

    The quality of life of a Cavalier with MVD is usually very good until the very end. One of my dogs is 13 and has a Grade 4 murmur (murmurs are graded between 1 and 6), and yesterday had his teeth cleaned. My vet uses isoflurene for the anesthesia and it is believed to be the safest form of anesthesia for a dog with a heart murmur. I picked him up a couple of hours later, and he was happy and lively!

    The best thing you can do is buy your Cavalier from a breeder who at least does the first part of the Protocol. Then, keep the WEIGHT DOWN on your Cavalier. Cavaliers are the greediest dogs on earth and are always hungry. It is up to the owner to ration their food properly. Obesity puts an unnecessary strain on the heart of a dog.

    Second, keep the teeth cleaned. Dental disease can lead to chronic infection and that can affect the kidneys. A dog with MVD and kidney disease is a vet’s nightmare – how one treats one disease, badly affects the other disease. Find a vet who is good with anesthesia and INSIST on isofluene for your Cavalier.

    Get your dog checked annually or or no longer than every two years by a BOARDED CARDIOLOGIST!!!! You need to know if your dog has a murmur and you need to know before he’s in congestive heart failure. Clinics are out there and your can find one with minimal effort.

    Suzanne R Brown
    THATCHCOTE Cavaliers
    Louisville, KY

  5. We had a purebred Newfoundland we got as a 8 week old puppy. At 6 years old he developed a heart arrhythmia. He had very little energy and tired easily. After a complete check-up his vet recommended his taking Dijoxion. He explained to us that if the drug worked on him it would seem like a miracle drug, he would have the same energy level as a young dog. The drawback was, after a length of time ( could be several months or more than a year he most likely would develop Dijoxion poisoning and most likely have to be put down.
    We decided to go ahead and give him the medication. He responded as if it truly was a miracle drug. He couldn’t wait to play and swim in our pool. Everyday he would be at the pool gate and bark to go swimming, it was “Wonderful”
    Then after just about one full year he got Dijoxion poisoning just as his vet said.
    It was like the rug was pulled out from beneath him.
    One morning it took him almost a half hour just to walk a few hundred feet to go to the bathroom. He could hardly breath and we knew his time had come.
    His vet came to our home to put him down.
    His final year that the drug gave him was so “GREAT” and this is what we will always remember him by.
    He was only seven when we lost him but they were seven wonderful years he gave our family that we will cherish for the rest of our lives.

  6. Thanks for another timely and pithy post.

    I have 2 dogs with coronary issues. The first is a senior guy someone dumped in a box outside the local humane society. The vet recommended him for humane euthanasia because of his age, bradycardia (~50 bpm) and Grade 5 heart murmur. Fortunately, the humane society was not ready to call it a day. He was in horrific condition… He could not walk, he could not sit, he could barely move. His claws were growing into his legs. He was more than 50% over his ideal body weight (33 lbs, 20 lbs ideal). When I tucked him into a sit, he rolled over backwards because he was so fat. My vet xrayed and saw his enlarged heart pressing into his lung space. We took him to the heart specialist; an echocardiogram which confirmed what we all suspected: valvular insufficiency. He is on lasix to reduce fluid build up and vetmedin to increase his contractions. He is still frail and he will never be healthy, but he loves his walks and does a mile easily. He has been out herding sheep. He now goes upstairs whenever he wants on his own. I trained him to sit and he might actually enter a rally class some day! I’m proud of his recovery, he has a lot of heart to go through what he’s experienced, yet he is a happy guy who looks forward to every day and it is great that he is getting a new chance to enjoy life.

    My other dog is my heart dog who is now a senior girl. I’ve been fretting about her for awhile now….. although her heart sounds are good, her mama passed from congestive heart failure last year and her brother littermate suffered that, too. This year, her physical showed elevated BNP enzyme (921 units), so she is scheduled for a visit with the cardiologist and an echocardiogram next week. I appreciate seeing your view that most heart issues are manageable with medications… thank you for that reassurance!

    I’d like to hear your thoughts about using BNP test as a routine diagnostic for asymptomatic seniors, and also your thoughts on its predictive value. I would also appreciate hearing any thoughts you might have on anesthesia safety for dogs with heart concerns.

Leave a Reply

Your email address will not be published. Required fields are marked *