Heart Disease and Your Dog

We want to pump you up!

The heart is pretty much a never-resting, pumping muscle. Blood flows from the body into the heart and once inside, the blood travels through four chambers. The top chambers are called the atria and the bottom chambers are called ventricles. The chambers are named after which side of the heart on which they are located. The atria and the ventricles are separated by valves. These valves open and close with each heartbeat (a heartbeat is a cycle of muscle contraction and relaxation that pushes the blood through). These valves are very important in preventing the blood from flowing in the wrong direction during a heartbeat. Below is the flow of blood:

From organs through veins →
Vena cava →
Right Atrium →
Tricuspid valve →
Right ventricle →
Pulmonary valve →
Pulmonary artery →
Lungs →
Pulmonary veins →
Left atrium →
Mitral valve →
Left ventricle →
Aortic valve →
Aorta →
Back out to organs through arteries

This flow of blood from organs, to and though the heart, through the lungs and back out to organs is a very important function in sustaining a healthy life. It allows for deoxygenated blood to pass through the lungs and become oxygenated and then carry the oxygen to the organs. Without oxygen, organs would not be able to function and would eventually shut down. Being able to catch anything that could hinder this flow is extremely beneficial to your pet living a long healthy life.

We Dogs

Most dogs that live long lives will be at an increased risk of developing some form of heart disease. Statistics show that:

  • 10% of dogs ages 5-8
  • 20-25% of dogs ages 9-12
  • 30-35% of dogs ages 13-16
  • 75% of dogs 16 years or old, will be affected by heart disease.

Heart diseases can either be caused by: Congenital Heart Defects – This means that they are born with a defect in their hearts and are usually diagnosed very early on or Acquired Heart Diseases – These are diseases that develop over a lifetime. 95% of dog heart diseases are acquired.

There are two most common acquired heart diseases that affect dogs, Degenerative Valve Disease and Dilated Cardiomyopathy.

Degenerative Valve Disease (DVD)
Degenerative valve disease is the most acquired common heart disease (70%), while the mitral valve is the most commonly affected valve (75%). In this disease, the leaflets that make up the valve become thickened. These thickened leaflets cause the edges to no longer touch or close correctly. This in turn allows for regurgitation, or backflow, of blood. Blood regurgitation causes turbulent blood flow inside the heart resulting in a loud murmur, most commonly heard on the left side of the heart.

Murmurs are chronic and progressive. The degree of severity is based on the amount of turbulent bloodflow heard. It is recorded on a scale of 1-6, with 1 being the weakest and 6 being the strongest. These are usually the first signs of changes within the heart and should be monitored by a veterinarian.

Degenerative Valve Disease is 1.5 times more commonly found in males than females. Some breeds are more likely to develop DVD than others.

Toy/Small breeds
Cavalier King Charles
Yorkshire Terrier

Miniature and Toy Poodle
Lhasa Apso
Mixed breeds
Small Spaniel breeds

Dilated Cardiomyopathy (DCM)
Dilated cardiomyopathy is the second most common acquired heart disease among dogs. This disease affects the heart muscle and the heart’s ability to pump blood effectively. All four chambers of the heart can become enlarged. This enlargement decreases the ability of the heart to contract which in turn decreases the ability of the heart to pump enough blood through the heart and body.
DCM can be very difficult to diagnose due to the fact that there are not many warning signs until the disease has significantly progressed. Larger breeds are more commonly affected by DCM.

Doberman Pinscher
Great Dane
Irish Wolfhound
Cocker Spaniel

St. Bernard
English Bulldog
Mixed breeds

A Weakened Heart Can Still Love Strongly!

The most important thing you, as an owner, can do for your dog is to make sure they are getting routine examinations by a veterinarian. Early detection and treatment are two ways to make sure your dog can live a long healthy life.

Examination – This is key to early detection. This time allows you to talk to the doctor about any changes you have noticed in your dog. This also allows the doctor to listen to your dog’s heart. They can hear the heart’s rate, rhythm, and if any heart murmurs are present. If there is a heart murmur, the doctor will be able to tell where it is located and the severity. At this time the doctor may suggest more diagnostic testing.
  • Bloodwork: To check for any changes in organ functions, white blood cell counts, red blood cell counts, platelet count, and heartworm disease. (When a heart murmur is heard on the right side it is very important to rule out heartworms as the cause.)
  • Radiographs: This allows the doctor to evaluate the size of the heart, to check for any tumors/masses, as well as looking at the lungs.
  • Electrocardiogram (ECG/EKG): This is a test that records the electrical and muscular function of the heart.
  • Echocardiogram: Ultrasound of the heart tells the size of chambers, the thickness of the muscles, the function of the valves, and the ability of the heart to contract. These are also used to check for leaks by following blood flow through the heart.
Treatments – Once a problem has been diagnosed, the veterinarian will start a treatment plan. These plans can vary based on the dog and the needs of that dog as well as the severity of the disease. Below are common drugs that are used either separately or in combination as part of the treatment.
  • ACE Inhibitors (angiotensin-converting enzyme): Used to open constricted blood vessels, reduce high blood pressure and reduce the onset of congested heart failure. Commonly called: Enalapril, Benazepril, and Ramipril.
  • Inodilators: Increase myocardial contractility. Open constricted blood vessels, decreases the workload on the heart. Commonly called: Vetmedin (Pimobendan).
  • Diuretics: Helps remove excessive fluid that tends to build up within the lungs and body. Commonly called: Lasix or Furosemide.

Other things to consider are diet and exercise. A diet that is sodium (salt) restricted as well as eliminating “people food” may be helpful in some cases. Exercise is very important for all dogs, but, dogs with heart disease may need to be limited. The best plan is to ask your veterinarian for a recommendation.

At-Home – There are things that you can monitor/watch for at home.
  • Decreased eating
  • Depressed acting/withdrawn
  • Weight loss
  • Less playful
  • Tires easily
  • Weakness
  • Changes in breathing: difficulty, shortness, labored, rapid
  • Cough that is worse with exercise and/or at night
  • Fainting spells – Usually related to irregular heart beat
  • Restlessness especially at night
  • Changes in gum color: Deep pink-normal healthy gums, Pale pink to white-Anemia, Gray/blue-decrease in oxygen level (Some dogs have a dark pigmentation of gums, lips and/or tongue. Usually black to purple in color.)

The most important key in keeping your dog healthy is to be seen by a veterinarian. Early detection will help ensure your dog can live a long, loving life. Not only does your dog have a special place in your heart, but they do in ours as well. We want to make sure that we take care of theirs!