The Stages of MVD
Heart murmurs in dogs and how to spot the signs
The Stages of MVD
What is a murmur?
Whilst there are a number of different causes of heart murmurs, in Mitral Valve Disease it is due to a squirt of blood being squeezed backward through the mitral valve when it should be a closed, non-return valve. The murmur can be heard by your vet when listening to your dog’s heart with a stethoscope.
Did you know?
Murmurs are scored by how loud they are (otherwise known as their grade), 1 is the mildest and can barely be heard even with a stethoscope, up to 6 which is the loudest and can be easily heard or felt on the dogs chest.
Although the grade of the murmur can help the vet decide how serious it is, extra tests are needed to understand whether treatment is needed. The most common test recommended is an ultrasound scan. This is a pain free procedure where a scanner is used to see the heart and all it’s structures to check for abnormalities.
Why does my dog have a heart murmur?
Murmurs can have lots of different causes. This website focuses on murmurs caused by a common heart disease called Mitral Valve Disease (MVD).
Your vet can’t know exactly what is causing your dog’s murmur just from listening to it. However, there are helpful clues that will help your vet decide which cause is most likely:
• Some dog breeds get MVD more commonly than others.
• Dilated Cardiomyopathy (DCM) is more common in large and giant breed dogs.
• MVD usually develops in older dogs.
Breeds commonly affected by Mitral Valve Disease (MVD)
• Cavalier King Charles Spaniel
• Small cross breeds e.g. Cavapoo, Cavachon, Whippet
• Poodle
• Yorkshire Terrier
• Shih Tzu
• Chihuahua
• Miniature Schnauzer
• Border Collie
The MVD Timeline
STAGE C
Murmur present – moderate to loud. Significant heart enlargement. Signs and symptoms of heart failure.
STAGE D
Eventually your dogs symptoms will reoccur despite treatment – this stage of their disease is called Stage D
STAGE A
No significant heart enlargement
Signs
- Dogs at high risk of developing heart disease but that currently have no identifiable structural disorder of the heart (i.e. no audible heart murmur at the time of examination).
Treatment
- No treatment is required at this stage and your dog doesn’t need any special care.
- As your dog is at risk of developing heart disease it’s a good idea to make sure they have a healthy diet and are a healthy weight.
- It is important that your dog has a regular health assessment every 6-12 months to ensure that if a heart murmur does develop it is identified as soon as possible.
What you can do
- Start measuring the Sleeping Respiratory Rate (SRR) monthly to establish a normal baseline for your dog.
STAGE B1 & B2
Heart enlargement
Signs
- As the murmur becomes louder your vet may recommend an ultrasound scan and/or x-ray of their heart.
- If changes have developed and the heart is significantly enlarged your dog will be classified as Stage B2.
Treatment
- Your dog is likely to seem healthy with no obvious signs of disease. However, treatment at this stage can help support your dog’s heart function. Your vet will discuss what treatment your dog needs at this stage.
What you can do
- Monitor the SRR weekly to help identify the onset of Stage C – heart failure.
Why are there two Stage Bs - B1 & B2?
It sounds complicated but there’s an important difference between these two sub-stages – B1 is when the heart has not yet enlarged significantly. Whereas B2 is when it has.
Practically speaking this means that as heart disease progresses it’s likely that your vet will recommend either an ultrasound scan and/or an x-ray of your dog’s chest to check the size of their heart.
If the heart is found to be enlarged, treatment is recommended even though your dog appears healthy. This can delay the progression of heart disease. Your vet will discuss this treatment with you.
STAGE C
Significant heart enlargement and heart failure symptoms
Signs
- You may notice signs of heart failure in your dog HOW TO SPOT THE SIGNS.
- The now very enlarged heart starts to fail and rather than pumping blood forward around the body it can start to build up in your dog’s blood vessels squeezing out fluid that usually then accumulates in the lungs and/or tummy.
- The fluid build-up is diagnosed using an x-ray of the chest or an ultrasound scan and other tests your vet feels are necessary.
Treatment
- The best combination of drugs to slow the progression of heart failure and help your dog feel as well as possible consists of a group of four drugs GO TO TREATMENT PAGE.
What you can do
- Measure the SRR to assess your dog’s response to treatment.
Managing heart failure Stage C
Stage C means your dog is showing clinical signs (or symptoms) associated with their MVD. Common signs include breathing faster or with difficulty, exercise intolerance, reduced appetite, restlessness at night, weight loss, and sometimes fainting or a cough.
What causes Heart Failure?
There are three main issues that develop in MVD that cause the symptoms we see associated with heart failure:
The enlarged heart starts to fail as a pump – leading to reduced ability to exercise, lethargy and weakness.
The enlarged heart takes up space in the chest – leading to more laboured/rapid breathing, restlessness when laying down and sometimes a cough.
The damaged valve and enlarged heart fail to pump blood round the body so fluid builds up in the lungs – leading to more laboured/rapid breathing and weakness/lethargy. Additionally the body reacts to the reduced blood flow from the heart and attempts to correct it by retaining more fluid in the kidneys – this attempt to support the heart is misplaced and worsens the build-up of fluid in the lungs. With a failing heart, holding on to extra fluid just gives the heart even more work to do.
Treating the condition helps to slow its progression, reducing the workload on your dog’s heart so they feel better for longer.
STAGE D
What happens when the medication becomes ineffective?
Heart failure is a progressive condition and although drug therapy can give your dog relief from the symptoms of heart failure and slow progression it can’t stop the disease. Eventually your dogs symptoms will reoccur despite treatment – this stage of their disease is called Stage D.
There’s no single solution for all dogs here – there are next steps and extra drugs that can be added or altered doses of your pet’s current medication may also be recommended. These drugs are less commonly used and your vet may recommend that you see a specialist heart vet – called a veterinary cardiologist, to advise you on extra treatment options at this stage.
It’s also very helpful to continue measuring the SRR for your dog and just like in Stage C to seek veterinary advice if their SRR is increasing at each check and/or if their SRR goes over 30 breaths per minute.
An additional step to help you decide if your dog is coping with their progressing heart failure is to score your dogs wellbeing or happiness and also their tolerance of exercise. Use a simple scoring system from 1 to 5 and record a score weekly for your dog so you can spot when they are starting to show a downward trend in their happiness or willingness to exercise.
Top Tip: Try scoring the following at least monthly so you can spot when your dog starts to show a decline in their scores. CLICK HERE