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Symptoms of Heart Disease in Dogs

Did you know that up to 75% of older dogs develop heart disease?

Symptoms of heart disease in dogs range from a mild cough to exercise intolerance. It’s normal for aging dogs to lose stamina over time, but could you tell the difference between a little fatigue and the absolute lethargy that comes with heart disease?

There are a few things you should know about heart disease in dogs, including the different types, how they develop, what to look for, and what to do about it.

Generally, there are a few things you want to look for: persistent cough, chronic lack of energy, and possible breathing problems. If you don’t know much about heart disease in dogs, keep reading!

Up Next: Is Grain-Free Dog Food BAD For Your Dog? Test Your Knowledge.

Symptoms of Heart Disease in Dogs vs Heart Failure

If the veterinarian believes your dog has heart disease, ask whether it’s early stage or late stage. Treatment options and outcomes will depend on whether any heart damage has already been done.

Heart Disease is a group of conditions that cause wear and tear on the heart muscle, leaving patients at risk for heart failure.

Heart Failure happens when disease has weakened or damaged the heart. When this happens, the heart can’t pump enough blood through the dog’s system.

This is a chronic condition requiring long-term treatment.

Symptoms of Heart Disease Require Proper Evaluation

If your dog is older and you’ve noticed a persistent cough, you are right in assuming that something is wrong.

Presenting with a simple cough isn’t enough for a veterinarian to make a diagnosis of heart disease. The cough is what you see and hear on the outside. 

In order to identify swelling or damage to the heart, the veterinarian has to have a look inside.

Canine cardiologists see heart disease as a chronic problem requiring long-term treatment.  They do not see it as a death sentence.

A recent article by the Cardiac Education Group ( reports that:

“chronic bronchitis is the most common cause of chronic coughing in mature dogs…”

Getting a Diagnosis of Heart Disease in Dogs

A full work-up is required to diagnose heart disease in dogs.  That means the vet will want to do some blood tests and a thoracic radiograph. 

The veterinarian will also ask about the dog’s history relative to how long he/she has been having symptoms. 

He/she will want to see the inside of your dog’s mouth for coloring (pale, bluish gums signify lack of oxygen) and will ask a variety of questions meant to narrow down the possibilities.

  “Not All dogs with heart failure cough, and not all coughs are associated with heart failure.”  Dr. Sonya Gordon, Associate Professor of Cardiology, Texas A&M University.

A thoracic radiograph (x-ray) presents an image of your dog’s heart which will show whether the organ is enlarged or not. Thoracic radiographs (chest x-rays) are non-invasive and painless.  

To get an accurate cross-sectional analysis of the heart, two images are taken.  First, your dog will be laid on his/her side in order to get the best picture. 

It’s important for your dog to be as still as possible and, in some cases, sedatives might be necessary.

Once that’s finished, your dog will be rolled onto his back and a front-chest image will be taken.

Taking a cross sectional image of the heart enables the veterinarian to determine whether the heart is actually enlarged, or normal in proportion to the dog’s size and breed.

 “Cardiac enlargement is usually present by the time heart disease has progressed to heart failure.” 

-Dr. Rebecca L. Stepien, Clinical Professor, School or Veterinarian Medicine, University of Wisconsin-Madison.

You Might be Interested in This: Dog Heart Murmur Life Expectancy Guide


Take a Few Minutes to Read: Life Expectancy of a Dog with Dilated Cardiomyopathy

Types of Heart Disease in Dogs

Mitral Valve Disease

The clinical term for a heart murmur is Mitral Valve Disease.

It’s typically diagnosed in puppies showing no symptoms. As the disease progresses, you may notice more coughing and your dog won’t be able to exert himself through exercise or play.  

Mitral Valve Disease is responsible for ¾ of all canine heart disease.

When MVD is discovered early, the dog can be treated with medication.  That medication helps to ease the burden placed on the heart, manages blood pressure and controls fluid retention.

Small Breeds Susceptible to Mitral Valve Disease (Heart Murmurs) Include:

  • Cavalier King Charles Spaniel
  • Chihuahua
  • Miniature Schnauzer
  • Shih Tzu
  • Maltese
  • Toy Poodle

Dilated Cardiomyopathy in Dogs (DCM)

Dilated cardiomyopathy is a disease that causes weakness of the heart muscle and an inability to adequately pump blood.

Large/giant breeds are more susceptible to dilated cardiomyopathy and include:

Great Dane

Labrador Retriever

Irish Wolfhound

Golden Retriever

Doberman Pinscher

Symptoms of heart disease in dogs tends to show itself later in senior dogs.

Hypertropic Cardiomyopathy

This condition affects a portion of the heart that becomes thickened. Symptoms may include fatigue, swelling, fainting, or heart failure.  When discovered early, this can be treated with medication. 

In some cases, an implantable cardiac defibrillator might be recommended.  Generally, this would be reserved for dogs who don’t respond well to other treatment measures. 

There is no known, identifiable cause for hypertrophic cardiomyopathy.

Restricted Cardiomyopathy

Restricted cardiomyopathy is less common and involves the heart valves becoming more rigid and not being able to stretch properly. This particular type of disease is rare and because of that, limited data is available.

Heart Disease in Dogs or Something Else?

Veterinarians/cardiologists want to be certain the dog actually has heart disease before beginning treatment.

 In addition to listening for cough, respiration rate, and radiograph analysis, the veterinarian will also take into consideration the age, size, and breed of the dog.

Before the doctor makes a diagnosis of heart disease, he/she will want to rule out other causes including:

Heart Worm

Heart worm is spread by mosquitos carrying the heartworm larvae. Dogs who live in hot, humid climates where there is a high mosquito population might be prone to heartworm. Symptoms, which include coughing and tiredness, could easily be mistaken for heart disease in an older dog. 

Heart worms are long and stringy, much like a piece of spaghetti. They infiltrate the heart and lungs, and if left to reproduce, cause permanent damage resulting in heart disease and death.

Chronic Obstructive Pulmonary Disease (COPD) or Chronic Bronchitis

COPD occurs when the dog’s airway becomes inflamed.  The first thing you’ll notice is the cough, which is likely the reason you brought your dog to the veterinarian in the first place.

While doctors are unable to narrow down any specific cause for this disease, it’s thought to be a result of long-term exposure to airborne irritants. Tobacco smoke, pollution, smog, chemical exposure, and allergens could all contribute to the disease. 

COPD is characterized by a dry, gagging cough that mimics the symptoms of heart failure.


Fluid in the lungs will make a dog cough. The dog will be tired because of the inability to absorb enough oxygen into his system. In addition, a dog with pneumonia isn’t going to be able to easily take a deep breath which results in a faster respiratory rate, as indicated above.  Your dog will probably have a fever and low appetite.

Lung Cancer

The difference in a cough caused by lung cancer as opposed to heart disease involves the spitting up of blood.  This is the most common cancer in dogs over 10 years of age.  Lung cancer spreads very quickly to other parts of the body including the organs, lymph nodes, bones, brain, and eyes.

If the veterinarian were to spend too much time on a false assumption of heart disease, something like this could be overlooked and, by the time it becomes apparent, could be too late.

Kennel Cough vs Heart Disease in Dogs

Have you traveled recently? Left your dog at a kennel? Kennel cough produces a terrible-sounding cough that would strike fear in the hearts of any dog owners.  Thankfully, it’s not considered a serious illness and can be treated with medications.

A dog is exposed to kennel cough the same way humans are exposed to colds and flu. Our immune systems become compromised, leaving us vulnerable to viruses.  The same thing happens to dogs. Dogs exposed to cigarette smoke, cold temperatures, or conditions like those seen in kennels are more likely to succumb to viral infections like kennel cough.

Treatment includes antibiotics. It’s also important to note that your dog can be vaccinated if he/she might be at higher risk.

Listening to Your Dog’s Breath Cycles

If the veterinarian isn’t able to make a definitive diagnosis right away, he/she may ask you to monitor your dog’s respiration rates for about a week.

*Important: Please take your dog to see a veterinarian as soon as possible. The following explanation is designed to give you an awareness of the procedure, not substitute an emergency visit.

Dog owners are often keenly aware of out-of-the-ordinary signs and symptoms. Have you noticed a change in your dog’s breathing rate?  If so, make sure to mention it to the veterinarian. You don’t have to know the exact respiration rate. Simply telling the doctor that you’ve noticed faster breathing will help tremendously.

Test Your Dog’s Breathing Rate

If you’ve ever had pneumonia, you understand how hard it is to take a deep breath. That’s because the lungs are holding water (edema).  When restricted that way, the lungs can’t expand and when that happens, your breathing rate becomes shallow.

The next time your dog curls up beside you, watch and count how often the chest rises within a 1 minute span.  COUNT ONE BREATH FOR THE ENTIRE RISE AND FALL OF THE CHEST DURING BREATH INTAKE.

  • Most dogs at rest will have a respiratory rate between 15 – 30 breaths per minute. REMEMBER: One breath includes the full rise and fall of the chest during inhalation and exhalation.
  • 35 breaths per minute is considered the cut-off, or maximum for most dogs.
  • Hot, recently active, or anxious dogs will normally experience a higher respiration rate, but it shouldn’t remain that way.
  • Breathing rates noticeably and consistently higher than 35 is a cause for concern.

It’s best if you have already established a baseline for your dog’s normal breathing rate, but most people don’t think of that when enjoying the companionship of a healthy dog.

That’s okay!  As mentioned above, simply noticing a faster breathing rate and telling the veterinarian about it is a huge help in aiding a fast diagnosis.

Ruling out Signs of Heart Disease in Dogs

If clinical signs don’t immediately point to heart disease, the veterinarian might suggest a broad-spectrum antibiotic to take care of any infectious disease that could be present.

If symptoms improve after a few days of antibiotics, the veterinarian will be reasonably assured that the presenting symptoms are not related to heart disease. 

However, depending on a number of factors (age, other health conditions, obesity), the veterinarian may still want you to monitor the dog’s conditions weeks after the last dose of medication in case the symptoms return. 

What Happens if it is Heart Disease?

Okay, the worst part – the waiting – is over.  Now you know what you’re dealing with and the veterinarian will be able to customized a treatment plan specific to your dog’s needs.

The veterinarian should use a combination of the following classifications to record your dog’s disease progression.

Classification of Heart Disease in Dogs

Class I     The dog shows no obvious systems of heart disease, even with heavy exercise.

Class II    The dog only shows clinical signs and symptoms during or after hard exercise.

Class III   A dog in this classification will exhibit signs and symptoms of heart disease doing moderate kinds of everyday activity.

Class IV   At this level, the dog is showing severe signs of heart disease, even when at rest.

Stages of Heart Disease in Dogs

Stage A.  In Stage A, the dog may be at higher risk of developing heart disease but has no immediate signs and symptoms that warrant deeper investigation.

Stage B.  The dog might have a heart murmur, but shows no signs of having developed heart failure.

  • B1 – The dog has no telltale symptoms of heart disease. Radiograph and echocardiogram show no evidence of disease.
  • B2 – A murmur could be present, but the dog hasn’t developed signs of heart failure or enlarged heart.

Stage C.  At this stage, heart disease has progressed but the dog can still be treated on an outpatient basis.

Stage D:  At stage 4, the heart disease has progressed to a higher level of seriousness that could result in death. All of the stages mentioned above are designed as guidelines to determine the best treatment options.

Identify symptomatic dogs with advanced heart failure from CVHD and refractory to conventional therapy—these patients require aggressive or new treatment strategies or potentially hospice‐type end‐of‐life care

Treatment Plan for Dogs with Heart Disease

Maintaining muscle mass in a dog with congestive heart failure is vital in preserving strength.  The clinical term for muscle wasting is cachexia.

Dogs with heart disease will often experience fluctuations in appetite ranging from sudden changes in food preference (known as dysrexia), to a reduction in the amount of food eaten (known as hyporexia) or a complete loss of appetite (known as anorexia).

In order to extend your dog’s life, it’s important to maintain a high-protein diet using healthy foods suggested by the vet.

High Protein Diets for Dogs With Heart Disease

At this stage of your dog’s life, the most important thing is feeding him/her protein from appropriate sources.  Dogs with heart disease tend to be lacking in certain vitamins and minerals, and you want to be sure that whatever you are feeding your dog adds these things to the diet.

Be prepared to change your dog’s food fairly often to make sure he’s getting the right ratio of nutrition that your dog specifically needs.  The most common deficiencies associated with heart disease in dogs include:


A building block for protein best obtained from meat and fish products. Taurine supports heart, brain, retina, and blood cell function. Although researchers are unable to specify exactly how taurine aids in the treatment of heart disease, it’s thought that this amino sulfonic acid eases nervous system functioning and may reduce blood pressure.

Omega 3 Fatty Acids

This fatty acid is normally only found in low doses from the dog’s diet, but can easily be supplemented. It’s thought to benefit dogs with heart disease because of the reduced inflammatory effects .


Dogs with heart disease might be prescribed a diuretic to reduce edema (swelling) in the lungs.  However, long-term use of diuretics can dilute the amount of minerals the body needs for health.  Without these minerals in the body, dogs will become weaker and at increased risk of arrhythmia (abnormal heart rhythm).

B Vitamins

Vitamins are also lost through the urine in dogs prescribed diuretics.  Not all commercial brand dog food contains the recommended amount of B vitamins (specifically, B6 and B12).  To make sure your dog is getting the recommended dose, use dog food formulated by a board-certified veterinary nutritionist.  Your vet will be the best guide in this situation.

  “If owners are feeding their animals home-cooked diets, a variety of vitamin (and other deficiencies” are possible. Studies have shown that, unless formulated by a board-certified veterinary nutritionist, nearly all home-cooked diets are nutritionally unbalanced.” – Dr. Lisa Freeman, School of Veterinary Medicine, Tufts University.

Avoid These Foods for Heart Disease in Dogs

  • baby food
  • bread
  • cheese
  • lunch meat
  • cold cuts
  • most pet treats
  • rawhides
  • bully stick

The food choices mentioned above are often high in salt and do not provide the necessary nutrients for dogs; specifically, dogs at risk of heart failure.

Do not leave the veterinarian’s office with a vague idea of what a heart disease diet should look like. If your veterinarian is not specific about a diet, make sure to ask. 

This is going to be a lifestyle change for you and your dog. Unlearning certain dietary behaviors is paramount to ensuring a good quality of life for your dog.

The Cost of Heart Disease in Dogs

The bottom line is that there’s hope.  You knew the day would come when your aging dog’s health would decline.  When you’re finally faced with a serious, chronic illness like heart disease, it can be an emotional roller coaster.  The overall longevity of your dog and his/her quality of life from this point rests on your shoulders.

Be Prepared to Spend More Money On:

  • More frequent visits to the veterinarian
  • Specialized dog food diets
  • Laboratory tests
  • Radiographs or x-rays
  • Echocardiograms
  • Prescription Medication
  • and possible surgery

Ideally, you would have pet insurance to stay ahead of the financial expense. However, if you don’t fall into that category, don’t be afraid to shop around for the best price.

If money is a problem, ask your veterinarian for a referral to a less-expensive clinic or discuss what other options might be available. Dogs are family, and we always want to do what’s best for family.

I really hope you were able to learn something valuable in this article and now, I’d like to ask you to share this with friends and/or family.  Whether you’re just in the process of getting a puppy, or nurturing a geriatric dog, anybody can find useful information on how to prevent and treat heart disease in dogs.

Go ahead!  Please take a second to share because it really helps me to keep this blog up and running.

Thank you for your time.


VCA Hospital


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