Cat Heart Murmurs

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Heart Murmurs in Cats

Charlie with Dr. Pat Perkins getting his back adjustedUnfortunately, heart murmurs are not just a human phenomenon – they can affect beloved pets as well, including cats and dogs. Heart murmurs can be difficult for vets to detect in pets for a variety of reasons, so it is important that pet owners are aware of this cat health issue so that they can encourage vets to spend more than a few seconds listening to their cat’s heart and ask the right questions. Here is a little more information on cat heart murmurs:

My Cat Has a Heart Murmur…What Does This Mean?

Murmurs are extra vibrations of the heart resulting from turbulent blood flow. These vibrations produce an audible “whooshing” noise along with the heartbeat. Some heart murmurs are harmless and pose no threat to a cat’s health, particularly in kittens, but others should be monitored and could be symptomatic of other heart problems.

Causes

Murmurs can have a variety of causes. Here are a few to be aware of:

  • High blood pressure
  • Hyperthyroidism
  • Abnormal heart valves
  • Dilated blood vessels
  • Thickening of heart muscles
  • Defect in the septum – wall between the right and left sides of the heart
  • Heart disease

These heart murmur causes vary in severity, but it is important to know that some murmurs could be symptomatic of more concerning heart problems, so always have your vet investigate a heart murmur further.

Symptoms

Since heart murmurs can be hard to detect, sometimes the only symptom is the sound of the murmur itself, which a vet should be able to hear through a stethoscope. However, sometimes the murmur is easy to miss if the quality of the stethoscope is poor, the vet doesn’t listen long enough, or they are not experienced enough to recognize the sound of a murmur. Sometimes new vets also might mistake a cat breathing heavily for a heart murmur, so usually further tests are needed to confirm and learn more about the murmur.

If a murmur is the result of a heart disease, cats might display symptoms including coughing, weakness, or unwillingness to exercise. Murmur symptoms can also become more intense if a cat is dehydrated.

Types

There are a few different ways veterinarians classify heart murmurs. The first step in understanding a heart murmur is classifying it by grade, which has to do with the intensity of the murmur in terms of volume – but the higher the volume does not necessarily mean that the heart disease is more severe. Here is how PetMD breaks down the grades of cat heart murmurs:

  • Grade I – barely noticeable
  • Grade II – quiet, but possible to hear through stethoscope
  • Grade III – moderately loud, usually related to blood circulation issues.
  • Grade IV – loud and radiates widely, often can be heard on the other side of the chest.
  • Grade V – very loud, possible to hear with stethoscope just barely on the chest, strong enough vibrations to be felt by touch.
  • Grade VI – very loud, also possible to hear with stethoscope just barely on the chest, and strong enough vibrations to be felt by touch.

In addition to classifying by grade, veterinarians can also categorize heart murmurs by configuration – plateau murmurs, crescendo-decrescendo murmurs, and decrescendo murmurs – depending on the turbulence of the blood flow and how the volume of the murmur changes.

Below are three common types of murmurs and the issues that cause them, according to PetMD. For a complete list, check out their Heart Murmurs in Cats page.

Systolic Murmurs – occur when the heart muscles contract

  • Heartworm
  • Hyperthyroidism
  • Anemia
  • Mitral and tricuspid valve heart failure
  • Cardiomyopathy and aortic valve insufficiency
  • Mitral and tricuspid valve dysplasia
  • Systolic anterior mitral motion (SAM)
  • Dynamic right ventricular outflow obstruction
  • Dynamic subaortic stenosis
  • Aortic stenosis

Continuous or To-and-Fro Murmurs – occur throughout the heartbeat cycle

  • Patent ductus arteriosus
  • Ventricular septal defect with aortic regurgitation
  • Aortic stenosis with aortic regurgitation

Diastolic Murmurs – occur in the instance where the heart is relaxing between beats.

  • Mitral and tricuspid valve stenosis
  • Aortic and pulmonic valve endocarditis (inflammation of the inner layer of the heart)

Diagnosis

If a vet does suspect a murmur, they will probably order further tests to confirm the presence of the murmur, determine what type it is, and discover any other underlying causes. Some of the tests for a heart murmur in older cats include:

  • x-rays
  • radiographs
  • Doppler studies
  • electrocardiograms
  • echocardiograms

Your vet might also order a blood test to check for certain types of murmurs, such as anemic murmurs. Some experienced vets can also diagnose heart murmurs using an ultrasound, though other vets might recommend that you visit a veterinary cardiologist as the next step. If the murmur is in a young kitten, vets might just recommend a follow up appointment in a few months, since some murmurs in young cats go away on their own.

Treatment and Prognosis: Heart Murmur in Cats Life Expectancy

Unless your cat is in immediate danger of heart failure, the vet will treat them as an outpatient. While treatment and prognosis are the biggest questions on pet owners’ minds who are faced with this diagnosis, the treatments and life expectancies vary greatly based on the type of heart murmur and any accompanying heart disease.

Generally, you might expect medication, supportive care, and continued monitoring. The murmur might also be completely harmless, especially if it is in a young cat, in which case the only course of action would be routine diagnostic check-ups.

Heart murmurs in cats can be wide and varied, so if you think your cat is having heart trouble or your vet identifies any unusual sounds during a check-up, the best thing you can do is get all of the routine tests done and wait for further treatment plans from your vet.

What experiences have you had with cat heart murmurs? What was the treatment plan? How did you or your vet diagnose the murmur?

Comments (8)

  1. Whoa. Great and informative post, Jenny! Thank you so much! To be honest, this is something I’ve never really thought about in all the years I’ve had cats and dogs in my life. Guess I’ve been pretty lucky. I really have no experience with this condition at all but I’m glad you shared this information so I can bookmark it “just in case.”

    Big hugs & lots of love!

    Patti & Miss Pink Sugarbelle 🙂 <3

  2. The only time a vet mentioned a heart murmur to me was this year, shortly before our 18-year-old kitty, Holy Tara, passed away. Dr. Rena just said she had a slight heart murmur.

    It’s good to know more about this condition. Thanks Jenny!

  3. We take our kittens to Kansas State University and most all litters have at least one kitten with a grade 1 or 2 heart murmur. These are called innocent heart murmurs and many kittens under the age of 6 months have them. Many times a kitten is under stress when taken to a vet and this can cause an intermittent heart murmur. All of our kitten have outgrown this by 6 months of age. I remember being freaked out when we had our first kitten with a heart murmur but found out it is nothing to worry about unless it continues past 6 or 7 months.
    “An innocent or physiologic heart murmur is a heart murmur that has no impact on the cat’s health.
    One type of innocent heart murmur is often found in young growing kittens, particularly kittens that are growing rapidly. The murmur may first appear at 6-8 weeks of age, and a kitten with an innocent heart murmur will usually outgrow it by about 4-5 months of age. This type of murmur is benign. Some normal adult cats may have an intermittent heart murmur that shows up when their heart rate is increased due to stress. This type of physiologic murmur disappears when the heart rate is normal, and has no impact on the cat’s health.
    In general, a physiologic or innocent heart murmur will have a low intensity (usually Grade I-II out of VI), and does not cause any symptoms or clinical signs.” Quote from vcahospitals.com/know-your-pet/heart-murmurs-in-cats.

  4. So glad to find this info on your site. Hunter went in for his 6 month exam this morning with a new vet (our 29 year vet just retired) and she heard a murmur. Now, I have to decide whether to do further tests to find out what’s causing it, or if it was just an “innocent” one. Complication is that he needs a dental cleaning done and they won’t put him under anesthesia without knowing about his heart. So, I guess that makes my decision! He is completely freaked at the vet, so I’m hoping it was just his heart pounding so fast.

    Lynn

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