What Does a Heart Murmur Mean for Your Dog or Cat?

What is a Heart Murmur?

Learning that your dog or cat has a heart murmur or irregular heartbeat can be frightening for any animal owner. However, understanding what exactly constitutes a heart murmur – and what doesn’t – can help you better grasp what the illness entails, should your pet be diagnosed with one.

A heart murmur is an abnormal sound that a veterinarian hears when listening to the pet’s heart through a stethoscope during a physical exam. Normally, your pet’s veterinarian hears two distinct normal heart sounds when they listen to the heart: lub-dub…lub-dub…lub-dub. When your vet hears an additional “whooshing” sound in between normal heart sounds, this is known as a heart murmur.

If your pet is diagnosed with a heart murmur, there is no reason to panic. Some heart murmurs are benign or harmless and may go away on their own, particularly in puppies and kittens. The only way to know the extent of your pet’s condition is to work with your veterinarian and/or a veterinary cardiologist (a specialist) to determine the cause of the murmur and the severity of the heart disease. Additional diagnostic testing may be required. 

What might cause a Heart Murmur in pets?

Anything that changes the blood flow through the heart can cause a murmur to be heard. Some of the common causes of heart murmurs in dogs and cats include:

• Heart valve deficiencies
• Defects in the heart walls
• Infection of the heart valves
• Hereditary cardiac defects
• Extra vessel connecting the great arteries (patent ductus arteriosus)
• Defects in the heart muscle walls (ventricular septal defect)
• Obstructive injury of the pulmonary valve (pulmonic stenosis)
• Obstructive injury below the aortic valve (subaortic stenosis)
• Defective mitral/tricuspid valve (mitral/tricuspid valve dysplasia)
• Acquired cardiac diseases
• Thickening of the heart valves (myxomatous mitral/tricuspid valve degeneration)
• Infection of the heart valves (infective endocarditis)
• Weakening or thickening of the heart muscle (cardiomyopathies)
• Dynamic obstruction of the right ventricle (a benign condition for cats)

Signs of Cardiac Disease

Not all dogs and cats diagnosed with a heart murmur will suffer from cardiac disease; alternatively, not all dogs and cats that suffer from cardiac disease will have a murmur. This is why your primary care veterinarian and/or veterinary specialist will weigh all your pet’s physical exam findings and history in deciding when and which additional tests are necessary.

If your dog or cat does exhibit signs of cardiac disease, a cardiac work-up will give you much-needed information. Signs of cardiac disease in dogs and cats can include:

• Difficulty breathing
• Rapid shallow breathing
• Cough
• Abdominal (stomach) distention
• Inability to exercise/weakness
• Gray or blue gums
• Possible collapse

If your pet is diagnosed with a heart murmur, it is important to always watch for these indicators. If your pet exhibits one more of these signs, contact your veterinarian or veterinary cardiologist. Emergency signals that warrant immediate veterinary involvement include:

• Blue or gray gums
• Collapse
• Cough
• Open mouth breathing and/or limb paralysis in cats 

Treatment

Treatment is designed to relieve the issues associated with heart disease related to the murmur. Most dogs and cats that have heart murmurs may live normal lives and never require treatment; others with more severe complications will benefit significantly from treatment, which can range from oral medications to surgery.

A veterinary cardiologist will tailor a treatment plan to improve your pet’s quality of life, as well as extend the time you have together. The good news is that a heart murmur is a clinical finding – not a disease diagnosis. 

What to expect after treatment

Depending on the cause of the heart murmur, treatment may sometimes “cure” the murmur. For instance, if your dog is diagnosed with a patent ductus arteriosus (extra vessel connecting the great arteries) with a heart murmur, successful treatment of the patent ductus arteriosus will resolve the heart murmur entirely, and a normal life-expectancy is anticipated. This is one example of how crucial it can be to investigate the cause of the heart murmur with further testing by a veterinary cardiologist.

If you have concerns about your dog or cat, and you need to locate a board-certified internal medicine veterinarian or cardiologist, use the VetSpecialists.com search tool on the website’s homepage. The tool allows you to search for a veterinary specialist, then select the type of animal along with your location by zip code or city name. Contact the hospital of your choice to discuss your pets’ condition and to review whether there is a need for a referral from your primary care veterinarian.