Your Dog Has a Heart Murmur (MMVD)
A 7-Day Action Plan
A step-by-step guide for the first week after an MMVD or heart murmur diagnosis. Print this page or save as PDF to keep it handy.
Day 1 - Breathe
A heart murmur diagnosis can be frightening, but MMVD is the most common heart disease in dogs - and many dogs live comfortably for years with monitoring and treatment. Today, your only job is to process this news. Write down exactly what your vet told you:
- What stage is your dog at? (A, B1, B2, C, or D)
- What is the murmur grade? (I through VI)
- What tests were done? (echo, x-ray, bloodwork?)
- What medications were prescribed, if any?
- When is the next appointment?
Day 2 - Understand the diagnosis
Learn what MMVD is and what your dog's stage means. Key things to understand:
- MMVD = the mitral valve degenerates over time and begins to leak blood backward
- Stage B1 = murmur present but the heart is still normal size (no treatment needed yet, just monitoring)
- Stage B2 = heart has begun to enlarge - this is when pimobendan (Vetmedin) is typically started
- Stage C = congestive heart failure (fluid in the lungs) - multiple medications needed
- MMVD often progresses slowly - many dogs stay at B1 for years, even a lifetime
Read: heartdogclub.com/articles/mmvd-stages-b1-b2-explained
Day 3 - Find a cardiologist
If you haven't already, get a referral to a board-certified veterinary cardiologist (DACVIM-Cardiology). A cardiologist can precisely grade the murmur, measure the heart with echocardiography, and determine exactly what stage your dog is at.
- Ask your vet for a referral
- Search our directory: heartdogclub.com/cardiologists
- Call to schedule - wait times can be weeks, so book now
- Key measurements they'll take: LA:Ao ratio (left atrium size) and LVIDdN (left ventricle size)
Day 4 - Learn your medications
Medications depend on your dog's stage. Not all dogs with MMVD need medication right away - Stage B1 typically requires monitoring only.
- Pimobendan (Vetmedin) - started at Stage B2. The EPIC study showed it delays heart failure onset by ~15 months. Give on empty stomach.
- Furosemide (Lasix) - used at Stage C to remove fluid from the lungs. Always provide fresh water.
- Benazepril / Enalapril - ACE inhibitors used at Stage C to reduce cardiac workload.
- Spironolactone - often added at Stage C for additional fluid management and heart protection.
Read: heartdogclub.com/medications
Day 5 - Start tracking respiratory rate
This is the single most valuable thing you can do at home. A rising resting respiratory rate is often the first sign that heart failure is developing or worsening - sometimes days before other symptoms appear.
- Wait until your dog is resting quietly or sleeping
- Count breaths (one rise + fall = one breath) for 30 seconds
- Multiply by 2 = breaths per minute
- Normal: under 30. Watch zone: 30-40. Call vet: above 40.
- Track daily - trends matter more than single readings
Use our free tracker: heartdogclub.com/tools/rr-tracker
Day 6 - Understand key measurements
These numbers from your dog's echocardiogram determine staging and treatment decisions. Ask your vet or cardiologist to explain your dog's specific results:
- Murmur grade (I-VI)- louder murmurs generally indicate more severe valve leakage, but grade alone doesn't determine staging
- LA:Ao ratio - compares left atrium size to aorta. Normal is under 1.6. At or above 1.6 suggests enlargement (Stage B2 threshold)
- LVIDdN - normalized left ventricle size. Above 1.7 indicates enlargement (Stage B2 threshold)
- Both LA:Ao ≥ 1.6 and LVIDdN ≥ 1.7 = the EPIC study criteria for starting pimobendan
Day 7 - Make a long-term plan
You've done the hardest week. Now set up for the long haul:
- If on medications, set up a schedule with alarms
- Schedule rechecks: every 6-12 months at B1, every 3-6 months at B2, as needed at C+
- Start a simple log: medications given, respiratory rate, any observations
- Many dogs with MMVD live comfortably for years - this is a manageable condition
- Connect with other dog parents going through this - you are not alone
Questions to Ask Your Cardiologist
Daily Respiratory Rate Tracker
Count breaths for 30 seconds while your dog sleeps, multiply by 2. Normal is under 30. Call your vet if consistently above 40.
| Date | Time | BPM | Notes |
|---|---|---|---|
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
Or use our free digital tracker: heartdogclub.com/tools/rr-tracker
Medication & Supplement Log
Record all medications and supplements your dog is taking.
| Medication | Dose | Frequency | With food? | Started |
|---|---|---|---|---|
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
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Your Dog Has a Heart Murmur (MMVD)
A 7-Day Action Plan
heartdogclub.com
Day 1 - Breathe
A heart murmur diagnosis can be frightening, but MMVD is the most common heart disease in dogs - and many dogs live comfortably for years with monitoring and treatment. Today, your only job is to process this news. Write down exactly what your vet told you:
- What stage is your dog at? (A, B1, B2, C, or D)
- What is the murmur grade? (I through VI)
- What tests were done? (echo, x-ray, bloodwork?)
- What medications were prescribed, if any?
- When is the next appointment?
Day 2 - Understand the diagnosis
Learn what MMVD is and what your dog's stage means. Key things to understand:
- MMVD = the mitral valve degenerates over time and begins to leak blood backward
- Stage B1 = murmur present but the heart is still normal size (no treatment needed yet, just monitoring)
- Stage B2 = heart has begun to enlarge - this is when pimobendan (Vetmedin) is typically started
- Stage C = congestive heart failure (fluid in the lungs) - multiple medications needed
- MMVD often progresses slowly - many dogs stay at B1 for years, even a lifetime
Read: heartdogclub.com/articles/mmvd-stages-b1-b2-explained
Day 3 - Find a cardiologist
If you haven't already, get a referral to a board-certified veterinary cardiologist (DACVIM-Cardiology). A cardiologist can precisely grade the murmur, measure the heart with echocardiography, and determine exactly what stage your dog is at.
- Ask your vet for a referral
- Search our directory: heartdogclub.com/cardiologists
- Call to schedule - wait times can be weeks, so book now
- Key measurements they'll take: LA:Ao ratio (left atrium size) and LVIDdN (left ventricle size)
Day 4 - Learn your medications
Medications depend on your dog's stage. Not all dogs with MMVD need medication right away - Stage B1 typically requires monitoring only.
- Pimobendan (Vetmedin) - started at Stage B2. The EPIC study showed it delays heart failure onset by ~15 months. Give on empty stomach.
- Furosemide (Lasix) - used at Stage C to remove fluid from the lungs. Always provide fresh water.
- Benazepril / Enalapril - ACE inhibitors used at Stage C to reduce cardiac workload.
- Spironolactone - often added at Stage C for additional fluid management and heart protection.
Read: heartdogclub.com/medications
Day 5 - Start tracking respiratory rate
This is the single most valuable thing you can do at home. A rising resting respiratory rate is often the first sign that heart failure is developing or worsening - sometimes days before other symptoms appear.
- Wait until your dog is resting quietly or sleeping
- Count breaths (one rise + fall = one breath) for 30 seconds
- Multiply by 2 = breaths per minute
- Normal: under 30. Watch zone: 30-40. Call vet: above 40.
- Track daily - trends matter more than single readings
Use our free tracker: heartdogclub.com/tools/rr-tracker
Day 6 - Understand key measurements
These numbers from your dog's echocardiogram determine staging and treatment decisions. Ask your vet or cardiologist to explain your dog's specific results:
- Murmur grade (I-VI)- louder murmurs generally indicate more severe valve leakage, but grade alone doesn't determine staging
- LA:Ao ratio - compares left atrium size to aorta. Normal is under 1.6. At or above 1.6 suggests enlargement (Stage B2 threshold)
- LVIDdN - normalized left ventricle size. Above 1.7 indicates enlargement (Stage B2 threshold)
- Both LA:Ao ≥ 1.6 and LVIDdN ≥ 1.7 = the EPIC study criteria for starting pimobendan
Day 7 - Make a long-term plan
You've done the hardest week. Now set up for the long haul:
- If on medications, set up a schedule with alarms
- Schedule rechecks: every 6-12 months at B1, every 3-6 months at B2, as needed at C+
- Start a simple log: medications given, respiratory rate, any observations
- Many dogs with MMVD live comfortably for years - this is a manageable condition
- Connect with other dog parents going through this - you are not alone
Questions to Ask Your Cardiologist
Daily Respiratory Rate Tracker
Count breaths for 30 seconds while your dog sleeps, multiply by 2. Normal is under 30. Call your vet if consistently above 40.
| Date | Time | BPM | Notes |
|---|---|---|---|
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
| ___/___ | ____:____ | ______ | _________________________ |
Or use our free digital tracker: heartdogclub.com/tools/rr-tracker
Medication & Supplement Log
Record all medications and supplements your dog is taking.
| Medication | Dose | Frequency | With food? | Started |
|---|---|---|---|---|
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |
| ____________ | ______ | ______ | ______ | ___/___ |