About 80% of dogs that get heart disease have a condition called Mitral Valve Disease (MVD). This progressive condition affects the mitral valve in a dog’s heart, leading to significant health challenges. Understanding MVD, its complications, and the available treatment options is crucial for dog owners to provide the best care for their pets.
What is the Mitral Valve?
The heart, a vital organ, consists of four chambers: two atria and two ventricles. The mitral valve, located between the left atrium and left ventricle, ensures that blood flows in one direction—from the atrium to the ventricle—preventing backflow. After the blood leaves the left side of the heart it is pumped to the rest of the dog's body.
What happens with Mitral Valve Disease?
In dogs with Mitral Valve Disease, the mitral valve becomes thickened and deformed, leading to an improper seal. This causes blood to leak backward into the atrium, a condition known as mitral regurgitation. Another name for Mitral Valve Disease is Mitral Valve Insufficiency. The cause for the valve to degenerate is not clear, but there is thought to be an inherited component in certain breeds. The earliest signs of mitral valve disease is a heart murmur, a whooshing sound when the heart beats. This correlates to the sound of the blood flowing in a backwards direction through the valve.
Causes and Risk Factors
Mitral Valve Disease primarily affects older, small-breed dogs such as Cavalier King Charles Spaniels, Dachshunds, and Miniature Poodles. Genetics play a significant role, and certain breeds are predisposed to the condition. Age is another critical factor, as the disease is often seen in dogs over the age of seven.
Symptoms of Mitral Valve Disease
In the early stages of MVD there are no clinical signs, but a heart murmur can be heard when the heart is listened to with a stethoscope. As the disease progresses, it will eventually cause the dog to go into congestive heart failure. The amount of time that it takes a dog to progress from just a murmur into congestive heart failure varies. Some dogs never go into congestive heart failure. Clinical signs associated with congestive heart failure are:
Coughing
Exercise intolerance, unwillingness to be active
Difficult breathing, rapid breathing when resting
Fainting episodes, called syncope
How is Mitral Valve Disease Diagnosed?
There a few different tests that can assess the heart and determine the presence of MVD.
First, is by your veterinarian auscultating a murmur on a regular physical examination. If this happens your veterinarian will likely recommend additional diagnostics such as:
Chest x-rays: x-rays can assess how big the heart is and also determine if there is any fluid in the lungs, called pulmonary edema. Pulmonary edema is a hallmark sign of congestive heart failure.
Heart ultrasound: ultrasounds of the heart are typically performed by cardiologists. During an ultrasound the veterinarian can visualize the valves of the heart to see how diseased they are and also measure how much blood is flowing in the wrong direction. They can also determine if the chambers of the heart are enlarged or if the walls of the heart have become thickened, also known as hypertrophied.
Treatment Options for MVD
Typically most medications will not be started unless there is evidence of congestive heart failure. One medication that is often started prior to any clinical signs is called Pimobendan. Pimobendan is in the class of drugs called an ionotope, it increases heart contractility and dilates blood vessels, improving heart efficiency.
Diet and Lifestyle Changes
A low-sodium diet can help manage fluid retention. Regular, moderate exercise is beneficial, but it's important to avoid overexertion. Weight management is also crucial, as obesity can exacerbate heart condition
Medications that are started once there is evidence of heart failure are:
Diuretics: Help reduce fluid accumulation in the lungs by having the kidneys remove extra fluid from the blood. They cause the dog to urinate more. Most common diuretics are furosemide and spironolactone.
Angiotensin converting enzyme (ACE) Inhibitors: Improve blood flow and reduce the workload on the heart. Enalapril and Benazepril are the most common ACE inhibitors.
In severe cases, surgical intervention may be considered. This is very uncommon and expensive, so most owners do not want to pursue surgical intervention. Mitral valve repair or replacement surgery is complex and typically performed by veterinary cardiologists. While surgery can be effective, it carries risks and is often reserved for dogs with advanced disease.
Dogs with Mitral Valve Disease face a serious yet controllable condition. Detecting it early and taking proactive measures are crucial to guaranteeing a comfortable and satisfying life for affected dogs. By understanding the illness, identifying its signs, and collaborating closely with a veterinarian, dog owners can effectively handle the difficulties of MVD and offer optimal care for their four legged friends.
If you suspect your dog may have Mitral Valve Disease or if they are showing any concerning symptoms, don’t hesitate to consult with your veterinarian. Prompt attention and appropriate treatment can make a significant difference in your dog’s health and quality of life.
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