What Are the Causes of Heart Disease?

Dogs Affected Chart

There are several ways your dog can be affected by heart disease:


Congenital Defects

  • Heart problems that your dog is born with
  • Will usually be diagnosed when your dog is very young (usually while still a puppy)
  • Account for a very small percentage of the diagnosed heart-related problems


Acquired Heart Disease

  • Accounts for 95% of all heart conditions2,3
  • Disease that develops during the course of your dog's life
  • There are two principal causes of acquired heart disease:
    • Valvular disease, which is also known as mitral valve disease or atrioventricular valvular insufficiency (AVVI). Normal heart valves open and close to ensure that blood flows through the heart in the right direction. In dogs with valvular disease, the valves thicken and become uneven, so the valve cannot form a perfect seal and blood may “leak” back in the wrong direction. Veterinarians can hear this backward blood flow with a stethoscope. The sound is called a heart murmur. It is a key sign of valve disease, which is most common in smaller breeds.
    • Dilated cardiomyopathy (DCM). Is another common form of heart disease, which is usually seen in larger breeds, the heart muscle becomes weak as the walls of the heart stretch and thin as the heart enlarges. Because the heart is weakened, blood is not pumped normally.


1. Atkins C, Bonagura J, Ettinger S, et al. Guidelines for the diagnosis and treatment of canine chronic valvular heart disease. J Vet Intern Med 2009; 23(6):1142–1150. 2. Buchanan JW. Prevalence of cardiovascular disorders. In: Fox PR, Sisson D, Moise NS, eds. Textbook of Canine and Feline Cardiology. Philadelphia, PA: WB Saunders; 1998:457-470. 3. Oyama M. Congenital heart disease. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. 7th ed. St. Louis, MO: Saunders Elsevier; 2010:1250–1298.

Facts about heart disease brochure

Learn more about canine heart disease…and help protect your dog’s heart.