Ever heard of myxomatous mitral valve disease (MMVD)? If your answer is no, then you’re not alone. I didn’t know what it was either until my dog Cas was diagnosed with it a few years ago.
After Cas’ primary vet detected that he had a heart murmur, I started taking him to a cardiologist for an annual echocardiogram (a test that uses soundwaves to create images of a dog’s heart). That is where I learned that the heart murmur was caused by MMVD. I was worried, but the cardiologist had emphasized that dogs with MMVD can live long, full lives if the disease didn’t get worse.
Unfortunately, the results from his latest echocardiogram weren’t good. Not only had the disease progressed, there was no stopping the inevitable: Cas will eventually go into heart failure.
How did we go from Cas living the rest of his life with just a heart murmur to one day going into heart failure?
For starters, MMVD causes the degeneration of the mitral valve, which is located between the two chambers on the left side of the heart. When the valve works normally, it opens to allow blood to flow from the top chamber to the bottom chamber and then closes to prevent blood from flowing backwards. As the valve degenerates, it creates a leak that causes the blood to flow back into the upper chamber. That backflow of blood is the source of the murmur, and it can eventually cause increasing pressure in the left chambers of the heart, which in turn causes the chambers to enlarge. All of this can lead to congestive heart failure.
MMVD is the most common heart disease in canines and affects about 80% of small breeds. The chances of a small breed getting it increases by 60% when they turn seven. It is categorized into the below stages to determine how advanced the disease is and if/when medication is needed.
Stage A: At risk of getting the disease, but no signs of a heart murmur.
Stage B1: Signs of a heart murmur.
Stage B2: There’s visible enlargement of the heart.
Stage C: Heart failure; symptoms can be managed with medication.
Stage D: Heart failure; medication is no longer effective.
Cas’ disease had originally been diagnosed as B1. Now it is categorized as B2. Medication isn’t necessarily automatic when a dog’s disease progresses to B2. How enlarged the heart is really determines when medication is recommended, and for Cas, the enlargement was labeled as moderate. This was enough for the cardiologist to suggest medication.
Medication isn’t a cure, but it buys more time. As Cas’ cardiologist explained it, it would be an estimated 6-9 months before Cas’ disease progressed to stage C. With medication, it delays it by 1-2 years. From a logical standpoint, the medication doesn’t delay heart failure by much, but from an emotional standpoint it gives Cas more time to live his life without symptoms.
As a mom to senior pets, I anticipated health issues to arise as they age, but it’s still hard to hear a diagnosis that brings no hope. Death was only a theory, a probability that I didn’t have to think about because why wouldn’t I think my animals would live forever?
Now I’ve been brought back to reality. The silver lining is that Cas doesn’t realize what is happening. He isn’t faced with his own mortality. He remains innocent and pure. I can take some comfort in that even as my heart breaks.
**
The information above is summarized from the sources below as well as the information provided to me by Cas’ cardiologist. I do not work in the veterinary field. I encourage you to conduct your own research or reach out to your dog’s vet to learn more about MMVD.
https://www.boehringer-ingelheim.com/animal-health/heart-murmur-dogs-symptoms-and-how-treat-it
https://vcahospitals.com/know-your-pet/mitral-valve-disease-in-dogs
https://veterinarypartner.vin.com/default.aspx?pid=19239&id=8526511
https://cardiaceducationgroup.org/resource-list/the-abcds-of-cardiology/
https://www.vetbuddyexpert.com/ClinicResources/ACVIM_Consensus_Statement_Infografic_updated.pdf
