Dog Heart Murmur Grades

Learn the grading system for dog heart murmur conditions. Discover the differences between life threatening heart murmurs and those that shouldn't cause any serious health problems. Understand what causes heart murmurs. Find out how much exercise your dog with a heart murmur should get.

Understanding Canine Heart Murmurs

A dog heart murmur occurs when blood flow inside the heart isn't normal. It can range from a poorly working valve or miscommunication between the left and right side of the heart. Heart murmurs are not always serious. They can occur simply because a dog was born with one or due to age or heart disease. Symptoms of a dog heart murmur include:

  • Blue tinge to lips, tongue and gums
  • Breathing difficulties, especially during and after exercise
  • Coughing, especially after exercise
  • Fainting during activity
  • Low tolerance for exercise

If your dog experiences any of these symptoms, contact your veterinarian. An EKG, chest x-ray and ultrasound can all help diagnose if there is a problem with blood flow within the heart. Some heart murmurs are treated by heart surgery, especially in situations where the heart murmur is caused by a birth defect. In some situations, as the puppy grows, the heart murmur vanishes without ever needing treatment. Other heart murmurs are best treated by using prescription medications.

To prevent any additional strain on your dog's heart, ensure that he's getting a proper diet. Do not overfeed the dog, provide him with high-fat treats or allow him to become overweight.

Grading System for Dog Heart Murmur

Dog heart murmurs are often graded. There are six grades in all, ranging from grade one to grade six. Grade one is so indistinct that many vets miss them. Only skilled canine cardiologists may hear the murmur and be able to diagnose it. By the time a heart murmur is grade five or six, the murmur is so pronounced that experts can detect it simply by feeling a dog's heart rhythm through the chest.

  • Grade One – Incredibly soft and barely noticeable
  • Grade Two – Very soft but easily diagnosed when listening through a stethoscope
  • Grade Three - Moderate dog heart murmur that is easily heard but lacks any vibration when the vet's hand is placed on the dog's chest
  • Grade Four – Loud with no noticeable vibration
  • Grade Five – Loud with some vibration but cannot be heard without the stethoscope
  • Grade Six – Loud with severe vibration and the veterinarian can hear it without a stethoscope

Exercise Tolerance for a Dog with Heart Murmur

If your dog has a heart murmur, talk to your vet about recommended activity. It's often advised to ensure your dog is getting exercise every day. However, strenuous activity is best avoided in dogs with grade five or six heart murmurs.

Ensuring your dog is kept inside during hot weather is important. The heart works harder if the dog is exercising in extreme heat. Hold off walks until sunset or sunrise when the temperature is cooler.

If you notice any sign that your dog is getting overexcited, calm him down. Placing him in his kennel for a nap can help, as most dogs tend to lay down and sleep once kenneled.