Heart Valve Regurgitation (Mitral/Tricuspid) in Dogs

The heart is comprised of four chambers. There are the atria and the ventricles, which are both responsible for allowing blood to flow. Two chambers, the atria, are above the other two, the ventricles. In addition to being divided from top to bottom, it is also divided from left to right. A valve, which only goes one way, is located in each chamber. It opens up to allow blood to flow into the chamber and then closes so the blood cannot “backflow” out, or regurgitate. When these valves do not work properly, it causes fluid to accumulate in the lungs because of the extreme amount of pressure and volume. 

The mitral valve is situated between the left ventricle and left atrium, and the tricuspid valve is situated on the other side of the heart amongst the right ventricle and right atrium. Both of these valves are known, together, as the atrioventricular valves, since both of them are situated between the atria and ventricles on either side of the heart.

Mitral/tricuspid regurgitation in dogs is a heart disease in which the valves of the heart do not function properly. The valves do not seal when they close, which causes blood to flow backwards into the previous chamber of the heart.

If your dog has mitral/tricuspid regurgitation, he will experience symptoms that are mild to severe. These symptoms may be similar to symptoms of other illnesses, so a veterinary diagnosis is necessary to rule out other conditions. Symptoms may include:

• Intolerance to exercise
• Coughing
• Breathing difficulties
• Rapid breathing
• Weakness
• Collapse

Types

This disease is predisposed and occurs in certain dog breeds more commonly than others. Types of dog breeds that are most affected include:

• Miniature Poodle
• Chihuahuas
• Cocker Spaniels
• Dachshunds
• Pomeranians
• Miniature Schnauzers
• Shih Tzus
• Maltese
• Cavalier King Charles Spaniels
• Whippets

This disease is genetic, but also has specific causes, especially in older dogs. Causes may include:

• The valve, made of elastic and collagen, weaken
• The spongiosa, which makes up the valve as well, becomes thicker
• The newly thickened valve has difficulty staying closed or does not close correctly
• The valve leaks, causing blood flow to reverse back into the previous chamber

If your dog is showing symptoms of valve regurgitation, make an appointment with your veterinarian. Once you arrive at your appointment, the veterinarian will take a closer look, ask specific questions about his symptoms, and perform a complete physical examination. The primary examination will consist of a urinalysis, blood testing, and a biochemistry profile.

Your veterinarian, upon receiving results, will then perform other tests which are specific to the cardiovascular system of your dog. Your dog will more than likely have a noticeable heart murmur which the veterinarian will be able to hear with a stethoscope. The medical professional may then conduct a radiography to take a closer look at the heart and lungs. The veterinarian may observe fluid in the lungs as well the size of the heart; valve regurgitation can cause the heart to swell.  Another tool your veterinarian may use to help further diagnose mitral/tricuspid regurgitation is an echocardiography. This is used to closely examine the valves of the heart and also the blood flow. This will show if any regurgitation is occurring. 

If there is a high level of regurgitation present, your veterinarian may perform a specific blood test, referred to as NT-proBNP, which can identify heart failure. Your veterinarian may also order other tests to help specify any other possible diagnoses if he feels the need to do so. These tests may allow the medical professional to check for other conditions, so if your dog needs specific medications to treat his heart condition, they will not interfere with any other possible abnormalities.

Once your dog is diagnosed with mitral/tricuspid valve regurgitation, there are a few treatment options your veterinarian will explain to you. Treatment options may include:

Medications

There are several different types of drugs which are used to effectively treat this disease. Your veterinarian will choose the proper drug according to your dog’s overall health, age, and heart condition. Your veterinarian may prescribe diuretics, vasodilators, or other medications to focus on specific issues your dog may be having, such as high blood pressure.

Monitoring

Your veterinarian will monitor your dog and possibly keep him overnight for further observation. He will also want to see your dog for repeated visits to perform the tests once again to check the effectiveness of the medication he prescribed. He may need to adjust the medication or try another if your dog is not responding after a few weeks.

Unfortunately, there is no cure for this disease. It can be controlled by medication and lifestyle changes. Your veterinarian will give you advice on any lifestyle changes, such as the prevention of overexertion, if he feels it is necessary. 

The prognosis of your dog’s condition depends on the severity of his disease. Your veterinarian will explain to you a more in-depth prediction of his prognosis; some dogs with this disease live a full life while others live less than a year. The diagnosis of your dog’s specific condition will give you more understanding of the stage of his illness. 

Be sure to follow your veterinarian’s advice on the administration of the medication, and to keep all follow-up appointments. Closely monitor your companion, and if you see signs of discomfort or any new symptoms, do not hesitate to call your veterinarian.