What is Degenerative Mitral Valve Disease in Dogs?

Introduction

Every evening, Emma cherished her daily walks with Charlie, her devoted Cavalier King Charles Spaniel. Over time, however, she noticed that Charlie was becoming increasingly fatigued and short of breath during their outings. Worried about her beloved companion, Emma took him to the veterinarian for a thorough examination. After careful evaluation, the vet diagnosed Charlie with degenerative mitral valve disease, a progressive heart condition that affects many dogs.

Mitral valve insufficiency (MVI) is a valvular heart disease where the mitral valve does not close properly. This allows blood to flow backward through the heart instead of forward. It causes congestive heart failure, shortness of breath, coughing, exercise intolerance, and fatigue. About 10 percent of dogs will develop some form of cardiac disease during their lifetimes, and most of these cases are caused by mitral valve insufficiencies. 

MVI may be congenital or acquired. Congenital MVI usually results from abnormal development of the valves during fetal life. Acquired MVI is often associated with degenerative valve disease, chordae tendinae, papillary muscles, or surrounding structures.

• The congenital Mitral Valve is commonly seen in large-breed dogs, especially Great Danes. Other breeds affected include Boxers, Doberman Pinschers, German Shepherds, Golden Retrievers, Labrador Retrievers, Rottweilers, Saint Bernards, Siberian Huskies, and Vizsla.

• Acquired Mitral Valve is standard in small breed dogs, including Chihuahuas, Maltese, Miniature Schnauzers, Shih Tzus, Yorkshire Terriers, and Toy Poodles.

If left untreated, MVI can lead to cardiovascular disease or death. The most common cause of MVI is a degenerative disease of the mitral valve leaflets. Other possible causes include congenital disabilities, rheumatic fever, bacterial endocarditis, trauma, and neoplasia.

Causes of Mitral Valve Disease in Canine

Mitral valve disease is caused primarily by wear and tear of your heart’s mitral valve. This occurs because the mitral valve doesn’t close entirely during each heartbeat. As it opens, blood flows backward into the left atrium. Over time, the leaflets become stiffer and less flexible, causing the valve to leak. If the leakage becomes severe enough, the valve no longer closes properly, allowing blood to flow backward into the left atrium during systole.

• Mitral Stenosis

The most common type of mitral valve disease is called mitral stenosis. In this case, the mitral valve does not open fully due to fibrosis or calcification of the valve tissue. When the valve fails to open completely, the pressure against the left ventricle walls increases, which stresses the muscle fibers surrounding the chamber. Eventually, the increased workload leads to the thickening of the muscles, scarring, and wall stiffness.

• Mitral Valve Regurgitation

Another type of mitral valve disorder is called mitral valve regurgitation. The valve doesn’t completely close off, so some blood flows back into your left atrium from your right atrium. Regurgitation usually happens when there are tears in one or both of the chordae tendineae, which are cords that connect the leaflet to the papillary muscle.

These tears allow the leaflets to prolapse or fold inward. Once the leaflets prolapse, the valve cannot seal tightly, resulting in leaking. As a result, dogs with mitral regurgitation may experience shortness of breath, exercise intolerance, and swelling in the left side of their neck or chest.

Infection of the valve is a rare cause of mitral valve disease. In this situation, bacteria enter the bloodstream and travel to the valve. They attach themselves to the lining of the valve, causing inflammation and scarring. Eventually, the valve begins to fail.

• Myxomatous Valve Disease

Myxomatous Valve Disease (MMVD) is another mitral valve disease affecting older dogs. It is characterized by thickened, rubbery-like tissues in the valve. The condition is more common in larger breeds such as Great Danes, St. Bernard Dogs, and Mastiffs.

Dogs with MMVD may have symptoms similar to those associated with other types of mitral valve disease, but they also often experience coughing, exercise intolerance, and weight gain.

Symptoms of Mitral Valve Disease in Dogs

Symptoms of MVI vary depending on the severity of the condition. Clinical signs may be mild, severe, or intermittent. A leaky valve may be detected by listening for a murmur. This occurs when blood flows backward from the right side of the heart into the left atrium because of a leaky mitral valve. Auscultation reveals a systolic rumble over the left side of the chest; the diastolic rumble is less audible.

For mild symptoms, occasional coughing, exercise intolerance, or fatigue are the possible signs. For severe ones, symptoms include difficulty breathing during exertion, rapid weight gain, lethargy, weakness, or syncope. Intermittent symptoms include palpitations, chest pain, dizziness, fainting, or lightheadedness.

Diagnosis of Canine Mitral Valve Insufficiency

Canine Mitral Valve Disease (CMVD) diagnosis is made by performing an echocardiogram and reviewing the results with a cardiologist. Echocardiograms are ultrasound tests used to view internal organs. They’re performed by placing a probe over the heart and watching the beating organ through a monitor.

• Electrocardiography (ECG) is a simple test used to diagnose heart problems in dogs. Electrodes placed on the dog’s chest record electrical activity from the heart. An ECG shows the pattern of these waves, called P waves, QRS complexes, T waves, and U waves.
• Chest X-Rays or chest radiographs are other diagnostic tools used to evaluate CMVD. Chest X-Rays are taken by positioning the patient inside a large machine called a CXR scanner. This device uses radiation to create an image of the lungs and heart.
• Cardiac Catheterization is a procedure where a small tube is inserted into a blood vessel in the groin area and threaded into the heart. Blood samples are drawn during this test. These samples are sent to a lab for analysis. Results are reviewed with a cardiologist who makes the final decision regarding treatment options.

Treatment options depend on the severity of symptoms and whether surgery is required.

Treatment for Degenerative Mitral Valve Disease in Dogs

Dogs with degenerative mitral valve disease can be treated with medication, dietary modification, and surgery. Medication helps reduce fluid retention and improve symptoms. Surgery can be performed to repair the mitral valve.

Medication

Two types of medications are used to treat MVD in dogs: diuretics and beta blockers. Diuretics reduce fluid retention, allowing blood pressure to return to normal. Beta-blockers slow down the heartbeat, reducing stress on the heart and improving its function.

Both treatments effectively relieve symptoms associated with MVD, including coughing, exercise intolerance, and fatigue. However, there are side effects associated with each treatment. Diuretics may cause electrolyte imbalances, kidney damage, vomiting, diarrhea, and dehydration. Beta-blockers may cause drowsiness, depression, weakness, muscle tremors, and stomach upset.

Dietary Modification

Dogs with mitral valve disease need special diets to help them heal properly. The diet should contain protein, carbohydrates, vitamins, minerals, and fiber. It should also include extra protein and omega fatty acids.

Some dogs may require additional supplements, including omega fatty acids, glucosamine, chondroitin, and vitamin D3. In addition, your vet can recommend specific foods based on your dog’s age, breed, weight, activity level, lifestyle, and medical history.

Surgery

There are many treatments available for canine mitral valve disease (CMVD). The most common treatment is surgery. However, there are several types of surgeries available. Some are minimally invasive, some require open heart surgery, and others are performed through a catheter.

Surgery is usually recommended when CMVD is severe enough to cause symptoms. Surgery may be done at any age, although older dogs fare better than younger ones. Older dogs often need multiple procedures over the years to correct the problem.

Prevention of Mitral Valve Insufficiency in Dogs

1. Preventing mitral valve disease in your dog starts with proper nutrition. Feeding a diet rich in omega-3 fatty acids has improved survival rates in dogs with mitral valve disease. Omega 3 fatty acids are found in fish oils such as salmon, sardines, herring, mackerel, tuna, trout, and anchovies
2. Other dietary supplements that may benefit dogs with mitral valve problems include antioxidants, probiotics, vitamin E, selenium, zinc, and garlic.
3. Proper dental care is another essential part of preventing pet mitral valve disease. Pet mitral valve disease Dental tartar buildup can cause inflammation of the gums leading to periodontal disease. Periodontal disease leads to gum recession, tooth loss, and eventually, infection of the heart valves.
4. Regular veterinary visits are essential to maintaining oral health. Regular brushing and flossing of teeth help remove plaque and tartar. In addition, cleaning teeth daily with a soft toothbrush and fluoride toothpaste reduces the risk of developing periodontal disease.
5. Keeping your pet active is another critical component in preventing mitral valve disease. Exercise improves overall health and prevents obesity. Dogs should walk for at least 30 minutes every day. Walking your dog regularly also keeps him fit and trimmed.
6. Avoid stress whenever possible. Stress can trigger episodes of vomiting and diarrhea in your pet, weakening the immune system and contributing to mitral valve disease.
7. Keep your dog’s immune system strong and avoid areas where he may encounter fleas or ticks. Flea infestations can cause irritation of the skin and coat, which can result in secondary infections. Ticks can transmit Lyme disease, Rocky Mountain sp, anaplasmosis, babesiosis, tularemia, and tick paralysis.
8. Ensure your dog receives regular vaccinations against infectious diseases such as parvovirus, distemper, hepatitis, rabies, and Bordetella bronchiseptica. Vaccination against these diseases protects your dog from contracting these illnesses.
9. It is essential to monitor your dog closely after surgery. Make sure your veterinarian checks his wound frequently to ensure healing correctly. In addition, monitor your dog for blue and watch excessive drainage from the incision site.
10. Besides monitoring your dog after surgery, ensure he gets plenty of rest and attention following any procedure. Avoid strenuous activity until your vet gives you clearance.

Frequently Asked Questions