Heart murmurs in cats

Heart murmurs are very common in cats.

A heart murmur means that in addition to the normal lub-dub heart sounds, a vet can also hear extra sounds when listening with a stethoscope.

This can indicate an irregularity with blood flow between the heart’s valves, which could affect oxygen and nutrients levels as blood is pumped around the body.

Murmurs can come and go. They can be heard when a cat is stressed and the heart rate has increased, but once the cat has calmed down can disappear.

We see a lot of cats at the NCAC showing heart murmurs, which are detailed on their medical summary, but these are generally considered to be stress related, by nature of being in our care, and can mostly disappear.

On its own, a heart murmur is not a reliable indicator of heart function and is commonly found in healthy cats. Many healthy cats with a heart murmur never develop any problems with their heart and go on to lead long, happy and healthy lives.

The prognosis depends on the cause of the heart murmur. 

Heart murmurs are graded 1-6, with 1 being of the least concern and 6 being of the most concern. Cats Protection will only refer a cat to a specialist if classed as grade 5 or 6.

The grade of murmur does not necessarily mean heart disease is more or less severe, or even present.

A murmur can occur because of another disease such as hyperthyroidism, high blood pressure or anaemia.

Heart disease can be diagnosed through a range of different tests:
  • Clinical examination
  • Stethoscope
  • Blood tests
  • X-rays
  • ECG
  • Ultrasound scan
On your next visit to a vet, we recommend that you speak to them about whether to investigate a heart murmur in an otherwise healthy cat.

The majority of cats will either have an innocent murmur or only mild structural heart disease, in which case the outlook is generally good and you can look forward to a long, happy life with your cat.