Heart Murmurs in Dogs

The dog heart is a very strong, yet intricate organ. Its main functions are to pump oxygenated blood through the body and to keep the blood moving forward. However, like human hearts, dogs’ can also experience murmurs. Murmurs occur when there is an obstruction in the flow of blood as it moves through your dog’s arteries or veins. Below is information on what causes heart murmurs in dogs and how they are diagnosed.

A dog may have a heart murmur; this does not mean he will not live a long life.

A heart murmur is not a reason to panic. It’s actually quite common in dogs, especially as they age. However, it’s important to note that not all dogs with heart murmurs have any kind of cardiovascular disease. Heart murmurs may be caused by many things (such as medications or infections), and require further testing to determine whether the dog has heart disease or some other condition causing the murmur. Even if your vet does find that your pet has a heart murmur, don’t assume he will not live a long life—many dogs live healthy lives after being diagnosed with one!

Two types of heart murmurs:

There are two types of heart murmurs:

  • Functional murmur. A functional murmur is a vibration caused by blood flow through the heart and the valves. This type of murmur can be detected by listening to your dog’s heartbeat with a stethoscope, but it does not mean your dog has a disease. Functional murmurs are generally harmless and do not require treatment unless they become louder or change over time.
  • Permanent heart murmur: A permanent or fixed murmur is present at all times, even when there isn’t any activity going on in the body that would cause loud sounds like running around or jumping up and down. This type of murmur can indicate an underlying condition that requires treatment, such as endocardiosis (congenital abnormalities of the heart valves).
See also  What to Do if Your Dog Is Vomiting White Foam

Functional heart murmur

A functional heart murmur is caused by a valve or other structure in the heart that is not working properly. It can be heard as a whooshing sound, most often when the dog is breathing in, and it’s more common in certain breeds like cavalier King Charles spaniels, Dalmatians, Poodles and Cocker Spaniels.

Most often these murmurs are temporary and will go away on their own over time. If your dog has one of these murmurs but doesn’t seem ill otherwise, you don’t need any treatment right away unless there are other issues present such as coughing or exercise intolerance.

Permanent heart murmur

If your dog has a permanent heart murmur, it is important to keep an eye out for signs of heart disease. Heart disease in dogs is common and may not show any symptoms until later on in life. Heart disease can be caused by congenital defects, injury to the heart or other structures surrounding the heart, viral infections such as canine parvovirus or feline panleukopenia virus (FPV), dietary issues like poor nutrition or exposure to toxins such as radiator coolant leaks, which are toxic for dogs.

If you notice any of these signs your dog may have heart disease:

  • Excessive panting or breathing with mouth open* Difficulty breathing* Rapid heartbeat (tachycardia)* Collapsing* Fainting/loss of consciousness

Causes of permanent heart murmurs

  • Congenital heart defects are the most common cause of congenital heart murmurs, which is why they’re also called “innocent” murmurs. These include ventricular septal defect and patent ductus arteriosus (PDA).
  • Infections such as bacterial endocarditis can cause permanent heart murmurs.
  • Cardiomyopathies such as dilated cardiomyopathy and hypertrophic cardiomyopathy also cause permanent heart murmurs by changing the structure of your dog’s heart muscle itself.
  • Valvular disease is another potential cause of persistent murmurs, including mitral valve prolapse, tricuspid valve prolapse, or hypertrophic cardiomyopathy.
See also  What to Do if Your Dog Has a Nose Bleed

Signs of heart disease

As you can see, there are a number of signs that your dog may be ill. If you notice any of the following in your pet, take him to the veterinarian immediately:

  • Getting tired easily and/or not eating as much as usual
  • Not drinking enough water or other liquids
  • Restlessness, panting and excessive drooling (panting is one of the most common signs)
  • Anxiousness or depression (dogs with heart disease often hide themselves away)
  • Lethargy (the opposite of being active)


To summarize, there are many different types of heart murmurs in dogs. The good news is that most of these conditions can be treated and reversed with medication or surgical intervention. If your dog has been diagnosed with one of the above heart murmurs, speak to your vet about what treatment options are available for him/her. With proper care and regular visits to the veterinarian’s office, it’s very likely that you will be able to keep your pet happy and healthy for their entire lifespan!