It’s the fifth month of a global pandemic, and you have finally decided to bring your super not-sick cat into the clinic for what will only be a regular annual exam, because nothing will ever happen to her and she is perfect and actually named after a minor character in a science fiction mini-series from the ’70s whose reference you will always be surprised is picked up by your vet who tends to type and talk in run-on sentences.
So all is going well.
You are sure of it.
You are waiting a tiny bit too long and you start to remember how your last sick cat once came to the vet and you had to wait 15 minutes extra and then got bad news. But then I come to your car and say that everything looks good [exhale], the annual blood work is normal on Meow Lamba [exhale], but …
BUT BUT BUT!!!!!! [heart sinks because this is not how the day was supposed to go and–what will it be?]
… but your sweet little cat has a very mild but notable heart murmur. You then hear nothing but a funeral march played on Moog synthesizers because Meow Lamba would want it that way.
As I say “heart murmur,” I see everyone’s face do one of two things: Eyes dilate and widen, mouth slowly goes agape and you are about to fall apart, or the muscles form the physical equivalent of “OK, Doc, be straight with me: how many months do I have left with her?”
I have to intervene immediately and dilute the words a bit, allowing you to fall back to earth and be able to talk out the rest.
And so: heart murmurs. Why do we often say not to worry, and then sometimes tell you to worry? Why do we send you to the cardiologist immediately sometimes, and more often tell you to monitor? Why did your last vet say you can never do a dental on her, and now I am telling you we can?
Let me help you. As with everything, each doctor has her own protocol, but I will give you some basics to consider. Each individual case may be different.
What is a murmur?
Lub Dub-Lub Dub-Lub Dub is the sound of the valves of the heart taking turns to close and effectively push blood through the heart. It’s not the only thing doing so, but gets most of the credit. Occasionally there will be some form of pathology to the valves causing them not to shut properly. Like a rattling screen door that doesn’t fit in the frame after years of humid summers and dry winters, the valves sometimes become misshapen or inflamed, causing the beautiful tell-tale lub-dub of the heart to sound more like lub-a-swish-dub-lub-a-swish-dub.
I liken it to someone turning up the reverb on a snare drum, but this analogy nails it for about none of my patients. So don’t worry when that means nothing to you.
To avoid making this into a veterinary textbook, I am not going to go into the pathophysiology of every reason a cat could get a heart murmur, but there are many: from congenital disorders (cats are born that way), to innocent ones caused by nothing at all, to underlying diseases (hyperthyroidism, etc.), to metabolic status (anemia, dehydration, high pressures, etc.).
The important thing to remember is that a heart murmur can be the result of something very serious, but in itself is not an emergency or an actual indication that a cat’s heart is progressing toward failure. I say this to a lot of clients, but my last cat (who was not named after a minor science fiction character) lived to be about a billion years old and had a Grade 3 heart murmur for all of those years with no clinical signs or progression.
This is not the same for every cat, though.
And then here is my first question: Is this a new murmur, or this is an old murmur that was either very hard to hear or the circumstance today (like being sick) is making the murmur sound more noticeable? Being dehydrated, sometimes being sedated or under anesthesia, being calmer or more excited can make a hard-to-hear murmur easier to hear.
If this is genuinely a new murmur, my next question is to understand if there are clinical signs of heart disease going on at home. These include coughing, wheezing, congestion, fluid from the nose, exercise intolerance, lethargy, or any type of respiratory noise. Now generally what happens is that when you hear about the murmur, you start to remember every single sneeze, wheeze, and cough that the cat (which was previously doing fine, with no issues) has had over the past year. It’s not that I discount the amended history, but heart disease is not the primary rule-out for any of the above clinical signs, so I take reports of these issues in context.
And if these things are not going on and the cat is still doing fine, then comes the choice of what to do. The most aggressive thing is to take x-rays to look at the size of the heart, to assess if the murmur is associated with other issues. Then sometimes, regardless, we discuss going to see a cardiologist where an ultrasound of the heart can evaluate those valves very specifically and make sure there is nothing going on.
Certain breeds of cats are more prone to issues, including the tragic and lovable Maine coons, Ragdolls, British shorthairs, Sphynxes, Norwegian forest cats, and Siamese. With these breeds, I generally err on the side of caution, but generally a happy healthy domestic short-haired cat that has a mild murmur and nothing else I will monitor and watch. I think it’s good to come back in a few months to recheck the murmur to make sure it is not progressing.
We do dentals and other anesthetic procedures all the time on cats with murmurs. It’s not that we don’t have to worry about it; it’s that we do. We take many precautions and monitor closely for any issues that are occurring during anesthesia. I think that sometimes cats with mild heart murmurs suffer much more from things like severe dental disease that goes unchecked because of the fear of putting them under anesthesia.
To be clear, you want to avoid anesthesia if possible, but it is not something that has to be avoided at all costs. Sometimes, again, going to a cardiologist before is recommended (and the safest things you can do).
I should say that despite my assurance that a heart murmur doesn’t always mean the worst, it can be. I don’t want anyone who is still reading this to think that I think that heart murmurs are a scam. There are animals that acquire heart murmurs and it is an early indication of heart disease that is serious. What you need to remember, though, is that there is a subtlety to it that is not so simple. Part of why annual exams on your cats are so important is so we can catch things like first-time heart murmurs and make sure that we are preventing any possible disease before it gets bad.
Shop local, love your cats, watch ’70s Canadian sci-fi,
Brett Grossman, DVM
Medical District Veterinary Clinic