Mitral Valve
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Our guide has been authored by qualified veterinarians, but should not be taken as substitute for medical advice or professional veterinary consultation. If your pet displays any unusual symptoms, we strongly advise seeking guidance from a veterinarian
Understanding Mitral Valve in dogs
Mitral valve disease in dogs is a common cardiac condition where the mitral valves, located between the atria and ventricle of the heart, do not close completely. The left atrium receives oxygenated blood from the lungs and passes it to the left ventricle, from where it flows to the entire body. The right atrium receives blood that has been used by the body’s cells and passes it to the right ventricle, and from there, to the lungs. The mitral valve is located between the left atrium and ventricle, and the tricuspid valve is located between the right atrium and ventricle. The role of the valves is to allow proper blood flow direction and thus prevent blood from flowing backward from the ventricle to the atrium during the heart’s pumping cycle.
In dogs with mitral valve disease, there’s leakage in the valves and blood returns with each heartbeat in the opposite direction. Over time, this constant leakage can lead to heart enlargement, impair its normal function, and eventually lead to heart failure, which is a life-threatening condition. The progression of the disease can vary from dog to dog, and some may live full lives without any clinical impact of the condition. However, for others, the disease can be life-threatening.
Rocky's story
When Rocky, the mixed-breed Pinscher owned by the Weiss family, began to show signs of tiring more easily and coughing frequently, his family initially attributed it to simply "getting older." However, Dr. Lodge found this explanation unlikely, as Pinschers typically reach their peak at the age of 8. He advised a visit to the clinic for a check-up. During the examination, a pronounced murmur was detected, and X-rays revealed a notable enlargement of Rocky's heart, putting pressure on his trachea. Rocky was promptly started on a regimen of continuous medical treatment, supplemented by monitoring his breathing. Five years have passed since then. At 13 years old, Rocky still enjoys life, leaps around, and, true to form, barks at everyone just as he did at the age of 3.
Mitral Valve's Causes: Uncovering Triggers
Mitral valve disease in dogs is mostly caused by a degenerative process leading to structural changes in the valves and, as a result, a disturbance in its normal function. It is assumed that the cause of this degenerative process is hereditary, as small dogs tend to develop the disease more often. The disease usually develops in mid to late adulthood, but some dogs may be affected at a young age, especially in certain breeds.
Recognizing Mitral Valve: Signs and Symptoms
- Coughing: Persistent dry cough, sometimes appearing as if the dog is "choking," is one of the clear signs of the disease. The reason for this is that in dogs, the enlargement caused by the disease is located just below the division of the trachea, exerting pressure and irritation on it. Later on, "wet" coughs may appear as a result of dangerous lung congestion.
- Breathing difficulties: Dogs with mitral valve disease may show increased respiratory effort, rapid or labored breathing, or even open-mouth breathing, whether during physical activity or at rest when the dog is lying down.
- Exercise intolerance: As the disease progresses, dogs may become easily fatigued during physical activity and may stop in the middle of a walk or pant heavily.
- Fatigue and weakness: Dogs with mitral valve disease may appear weak, tired, lethargic, or less active than usual.
- Collapsing: In severe cases, dogs with mitral valve disease may experience episodes of syncope - temporary loss of consciousness or collapse.
Mitral Valve Diagnosis: How it's Identified
- The most prominent sign of mitral valve disease in dogs is the heart murmur heard when listening to the heart sounds with a stethoscope. This is essentially the noise of the abnormal backward flow from the ventricles to the atria. If such a murmur is not heard, it is unlikely that significant mitral valve disease is present. In addition to that, the veterinarian may use additional tests.
- X-rays of the chest can help evaluate the size and shape of the heart and provide useful information about the condition of the trachea, the lungs, and blood flow patterns. An echocardiogram is a cardiac test using a special ultrasound device that allows direct examination of the structure and function of the heart chambers, valves, and blood flow patterns. An ECG will display the electrical activity of the heart and may indicate an enlargement of the heart chambers associated with the disease and, no less importantly, rhythm disturbances that may occur.
Treating Mitral Valve: Options and Approaches
- During the initial stages of the disease, medical treatment is not yet effective, and therefore, the main emphasis is on monitoring respiratory rate, regular follow-up, and managing a tailored lifestyle, including a low-sodium diet, maintaining proper weight, and appropriate physical activity.
- With the appearance of signs indicating impaired heart function, pharmacological treatment will be given, along with close cardiac monitoring. The medications will improve cardiac function and assist the heart in reducing abnormal flow. Sometimes ACE inhibitor drugs are also included. In more advanced stages of fluid accumulation in the lungs, medications will be given to reduce fluid and remove it through urine.
- Sometimes cough medications are given in cases of chronic tracheal inflammation due to the irritation/compression caused by heart enlargement. In contrast to humans, valve replacements through catheters are not practically possible in most dogs. Other surgical interventions, such as repairing or replacing the mitral valve, do exist theoretically, but they are very complicated and rare in veterinary medicine.
Mitral Valve: Surprising Facts
Mitral valve disease is the most common cardiac disease in dogs and the leading cause of cardiology visits. More than 10% of dogs suffer from the condition, even if they have no visible clinical signs.
The disease occurs more in small breeds compared to large ones and more often in males than females.
It is also one of the common diseases in older dogs. On average, one in every five dogs over the age of 9 and one in every three dogs over the age of 13 suffer from the disease.
Vet's Tip: Dealing with Mitral Valve
Mitral valve disease is a chronic-progressive disease – meaning it will not disappear, and over time, it may worsen. Our most important goal is to slow down the progression of the disease so that the dog can live as long and have as great of a quality of life as possible. One of the best monitoring methods for this purpose is a simple action of counting the dog’s respiratory rate at rest. In recent years, several specialized applications have been introduced to the market that can assist you with this. It’s a vital action that can be more important than any advanced monitoring device for the disease, as often, a mild but consistent increase in respiratory rate will occur long before life-threatening worsening.
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Latest in Research and Treatments
As mentioned, medical treatment does not address the valve itself but rather the associated problems. Surgical procedures to repair the valves are currently difficult in dogs. The great hope lies in the announcement of two major companies in the market collaborating on the development of genetic therapy for Mitral Valve Disease in dogs. This way, a short genetic segment can be implanted into the cells of the sick dog, producing a protein to prevent further deterioration of the valve tissue. Such treatment could be a breakthrough in veterinary medicine, especially for such a common problem.
dogs breeds Prone to Mitral Valve
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