What Is Mitral Valve Disease in Cavalier King Charles Spaniels?

 

Mitral Valve Disease (MVD), also known as Mitral Valve Insufficiency or Mitral Valve Regurgitation, is a common and serious heart condition, especially in Cavalier King Charles Spaniels. This disease affects the mitral valve, one of the four valves in the heart, which controls blood flow between the left atrium and the left ventricle. It affects up to 50% by age 5, nearly all by age 10. 

Recognizing and understanding MVD in Cavaliers is crucial because early detection and management can significantly improve a dog's quality of life and longevity. Given the breed's predisposition, regular veterinary check-ups and proactive monitoring are essential in managing this disease.

Function of the Mitral Valve

The mitral valve, consisting of two leaflets (or cusps), plays a crucial role in heart function by regulating blood flow between the left atrium and left ventricle. During the heart's contraction phase, known as systole, the mitral valve closes to prevent the backflow of blood into the left atrium. This ensures that blood moves efficiently from the left atrium to the left ventricle and then onward to the rest of the body. Proper functioning of the mitral valve is essential for maintaining healthy circulation and heart efficiency.

How the valve degenerates?

Over time, the valve leaflets thicken and may calcify, leading to reduced flexibility and improper closure. This degeneration results in valve prolapse, where the leaflets fail to seal tightly during the heart's contraction, causing blood to leak backward into the left atrium. 

As the disease progresses, regurgitation worsens, placing increased strain on the heart and leading to an increase in blood volume and pressure in the left atrium. The left atrium and left ventricle may become enlarged (dilated) over time due to the increased workload Eventually, the heart can no longer compensate, leading to congestive heart failure (CHF), where fluid accumulates in the lungs and other parts of the body.

Stages of MVD

Stage A: At risk for MVD but no current signs (Cavaliers inherently fall into this category due to breed predisposition).

Stage B: Presence of a heart murmur but no symptoms of heart failure.

Stage B1: Murmur present, but no heart enlargement.

Stage B2: Murmur with evidence of heart enlargement.

Stage C: Symptoms of heart failure present (e.g., coughing, difficulty breathing) and medical treatment is needed.

Stage D: Advanced heart failure with severe symptoms, often requiring intensive medical management.

Symptoms of each stage

Stage A: Cavaliers, though at risk for Mitral Valve Disease, currently show no signs of the condition, emphasizing the importance of proactive measures for early detection and prevention.

Stage B: While a heart murmur may be detected, indicating valve abnormalities, there are no observable symptoms of heart failure; regular veterinary check-ups are vital during this stage to monitor progression and initiate appropriate interventions.

Stage B1: Despite the presence of a murmur, there is no discernible evidence of heart enlargement, highlighting the need for continued monitoring and potential lifestyle adjustments to manage the condition.

Stage B2: Alongside the detection of a murmur, evidence of heart enlargement becomes apparent, signaling a progression in the disease; close veterinary supervision and possibly medication may be required to alleviate symptoms and slow disease advancement.

Stage C: Symptoms of heart failure, such as coughing and difficulty breathing, manifest, necessitating immediate medical attention and intervention to alleviate discomfort and improve the dog's quality of life.

Stage D: Advanced heart failure presents with severe symptoms, often requiring intensive medical management, including medications, dietary adjustments, and lifestyle modifications, to address complications and provide palliative care.

Complications of MVD

Left-sided Heart Failure: Fluid accumulates in the lungs (pulmonary edema), leading to coughing and difficulty breathing.

Right-sided Heart Failure: Fluid accumulates in the abdomen (ascites) and extremities, causing swelling.

Atrial Fibrillation: Irregular heart rhythm that can further complicate blood flow and increase the risk of stroke.

Pulmonary Hypertension: Increased blood pressure in the lungs due to chronic high pressure from the regurgitating blood.

Diagnosing and monitoring Mitral Valve Disease (MVD)

During a veterinary examination, the presence of a heart murmur, detected through auscultation (listening to the heart), suggests abnormal blood flow within the heart. Additionally, imaging techniques like echocardiograms and X-rays provide detailed visualization of the heart's structure and function, aiding in the assessment of MVD progression. Electrocardiograms (ECGs) are also utilized to evaluate heart rhythm and identify any irregularities, ensuring comprehensive monitoring and timely intervention for affected dogs.

Mitral Valve Disease poses a significant health challenge for Cavaliers, with a high prevalence and potential for serious complications. Through regular veterinary care, early detection, and proactive management strategies, such as medication and lifestyle adjustments, owners can significantly improve their pets' quality of life and longevity. 

Read: Are You Doing These 5 Things To Delay & Manage MVD In Your Cavalier King Charles Spaniel

Read:  5 Miracle Heart Supplements That Can Save Your Cavalier King Charles Spaniel’s Life

 
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