A Comprehensive Look at the Stages of Mitral Valve Disease in Dogs

Mitral valve disease (MVD) is a prevalent heart condition in dogs, particularly small breeds. This condition affects the mitral valve, which is important for controlling blood flow in the heart. Over time, the valve may weaken, compromising its function and leading to progressive heart problems if not addressed. Recognizing the stages of MVD is essential for giving the right care and helping affected dogs live a better life. Early detection, effective treatment, and lifestyle adjustments can significantly enhance their lifespan and well-being.

What Is Mitral Valve Disease in Dogs?

Mitral valve disease occurs when the valve between the left atrium and left ventricle of the heart begins to break down, affecting blood flow. Over time, the valve weakens and thickens, leading to improper closure and allowing blood to leak backwards (mitral regurgitation). This inefficiency places extra strain on the heart, eventually causing heart failure if left untreated.

Common Causes and Risk Factors:

• Breed Predisposition: Small breeds like Cavalier King Charles Spaniels, Dachshunds, and Chihuahuas are at higher risk.
• Age: The condition is more common in older dogs, typically developing in middle age.
• Genetics: Some dogs inherit a predisposition to MVD.
• Lifestyle Factors: An unhealthy diet and insufficient physical activity can accelerate the progression of heart disease.

Overview of the Staging System

Staging is a crucial part of managing mitral valve disease (MVD) in dogs. It helps veterinarians assess how advanced the condition is, guiding treatment decisions and offering a clearer prognosis. Early detection and timely care can greatly extend a dog’s life while improving their overall comfort and quality of life.

The most commonly used system is from the American College of Veterinary Internal Medicine (ACVIM):

• Stage A: Dogs at risk but with no signs of MVD.
• Stage B: Dogs with a heart murmur but no symptoms (subdivided into B1 for mild cases and B2 for more advanced ones).
• Stage C: Dogs showing signs of heart failure like coughing or tiredness.
• Stage D: Dogs with severe diseases that don’t improve despite treatment.

This staging system helps vets and owners work together to ensure dogs get the best care at each stage.

Detailed Breakdown of Mitral Valve Disease Stages

Stage A – At Risk

Dogs are genetically predisposed to MVD but do not show symptoms or heart abnormalities. This stage primarily affects breeds more susceptible to MVD, including Cavalier King Charles Spaniels and Dachshunds.

Characteristics:

• No noticeable symptoms or heart murmurs are present.
• Certain small-breed dogs have a higher risk due to genetics.

Recommendations:

• Regular veterinary checkups, ideally once a year, to monitor overall heart health.
• Routine heart screenings, including auscultation (listening for murmurs) for high-risk breeds.
• Keep your dog at a healthy weight and provide a balanced diet to lessen the burden on the heart.
• Encourage gentle exercise and avoid stress.

Stage B – Pre-Clinical Disease

Dogs with a detectable heart murmur due to MVD but no visible symptoms of heart failure. This stage marks the progression of the disease, but it remains asymptomatic.

Subdivisions:

• B1: The heart is not enlarged, and no clinical signs are evident.
• B2: The heart is enlarged, but the dog remains symptom-free.

Recommendations:

• An echocardiogram is essential to evaluate heart size and function accurately.
• For B2 cases, early medication (e.g., pimobendan) may be prescribed to slow disease progression.
• Schedule veterinary checkups every 6-12 months to monitor changes.
• Maintain a balanced diet, avoid high-sodium foods, and encourage low-impact activities.

Stage C – Clinical Disease

Dogs that have progressed to symptomatic MVD exhibit clear signs of heart failure. At this stage, the disease significantly affects the dog’s quality of life.

Common Symptoms:

• Persistent coughing, especially at night or during rest.
• Difficulty breathing, often accompanied by an increased respiratory rate.
• Reduced energy levels and intolerance to exercise.
• Loss of appetite and possible weight loss.

Treatment & Management:

• Prescription medications such as diuretics (to reduce fluid buildup), ACE inhibitors, and pimobendan to support heart function.
• In severe cases or emergencies, oxygen therapy may be necessary to help with breathing.
• Switch to a low-sodium diet to ease the burden on the heart.
• Carefully monitor exercise and provide a comfortable, low-stress environment.
• Regular veterinary visits every 3-6 months to adjust treatments as needed.

Stage D – End-Stage Disease

This is the advanced stage of MVD, where the dog experiences severe heart failure, and standard treatments are no longer effective. This stage requires intensive care to manage symptoms and maintain comfort.

Characteristics:

• Persistent symptoms despite medication, including severe coughing and laboured breathing.
• Frequent episodes of collapse, extreme weakness, or fainting.
• Significant fluid accumulation in the lungs or abdomen, causing discomfort.

Palliative or Advanced Care Options:

• Adjust medications to maximize symptom relief, possibly including stronger diuretics or additional therapies.
• Consider surgical options such as mitral valve repair for dogs despite limited availability.
• Focus on palliative care to provide comfort, including managing pain and reducing stress.
• Keep the dog in a calm, quiet environment and prioritize their emotional well-being.
• By understanding and addressing each stage, pet owners and veterinarians can work together to provide the best care and improve the quality of life for dogs with MVD.

Diagnosis and Monitoring

Diagnostic Tools:

• Auscultation: The vet listens to the heart with a stethoscope to detect murmurs, often the first signs of MVD.
• Echocardiography: This ultrasound test provides detailed images to evaluate valve function, heart size, and signs of enlargement.
• X-rays are useful for detecting fluid buildup in the lungs and assessing overall heart shape and size.
• Electrocardiogram (ECG): Measures heart rhythm and helps identify abnormalities, such as arrhythmias.

Frequency of Checkups:

• For Stage A and Stage B1 dogs, annual exams are recommended to monitor heart health.
• Stage B2 dogs should have checkups every 6 months to track heart enlargement and adjust treatment if needed.
• For Stage C and Stage D dogs, more frequent visits every 3 to 4 months are necessary to closely manage symptoms and ensure medications are effective.

Treatment Options for Each Stage

Medication Types and Their Roles:

• Diuretics: Help remove excess fluid from the lungs, easing breathing and reducing coughing.
• ACE inhibitors: Relax blood vessels, lower blood pressure, and reduce the workload on the heart.
• Pimobendan: Improves the heart’s ability to pump blood more effectively and supports better circulation.

Lifestyle and Home Care:

• Feed a heart-healthy diet, focusing on low-sodium foods and high-quality protein to support overall health.
• Managing your dog’s weight is key to reducing unnecessary pressure on the heart.
• Allow moderate, low-impact exercise to keep muscles strong without overexerting the heart.
• Provide a calm and stress-free environment to support emotional well-being.

Surgical Intervention:

• Mitral valve repair can restore valve function and significantly improve life expectancy for some dogs with advanced disease.
• This procedure is highly specialized and available only in select veterinary centres with advanced expertise.

When to Seek Expert Care for Your Pet?

Worsening symptoms of mitral valve disease, such as persistent coughing, laboured breathing, fainting, reduced energy, or loss of appetite, require immediate veterinary attention. Other concerning signs include rapid breathing during rest or swelling in the abdomen. These symptoms may indicate progression to heart failure. Consulting a veterinary cardiologist ensures that your dog receives advanced care, including adjustments to treatment plans. Addressing the condition early can lead to better management, increased comfort for your dog, and a longer life. Regular checkups and swift action on new symptoms are crucial for your dog’s health and well-being.

Conclusion

Understanding the stages of mitral valve disease in dogs is key to managing the condition effectively. With early detection, proper treatment, and simple lifestyle adjustments, many dogs with MVD can enjoy longer, happier, and more fulfilling lives. Frequent veterinary visits, ongoing monitoring, and prompt response to worsening symptoms help provide your pet optimal care, enhancing their overall well-being.

FAQs

How many stages of mitral valve disease are there in dogs?

There are four stages of Mitral Valve Disease in Dogs: Stage A (at-risk), Stage B (pre-clinical, with B1 and B2 subdivisions), Stage C (clinical heart failure), and Stage D (end-stage disease), each requiring different care and treatment.

What is the progression of mitral valve disease?

Mitral Valve Disease progresses from Stage A (asymptomatic at-risk) to Stage B (heart murmur), then to Stage C (clinical heart failure). Eventually, in Stage D, the disease leads to severe heart failure, requiring treatments like mitral valve repair in dogs.

How long will a dog live with Stage B2 heart disease?

Dogs with Stage B2 Mitral Valve Disease can live for several years with proper care. Medication, regular checkups, and lifestyle changes help slow the progression of the disease, ensuring comfort and quality of life before considering mitral valve repair in dogs.