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Heart Murmurs in Cats - Hypertrophic cardiomyopathy ❤️

Updated: Nov 9, 2022

During your cat's annual health check your vet will listen to their heart. This is to check it is working as it should be. Heart murmurs occur when there is turbulence in the blood flow within your cat's heart, imagine it a bit like the sound of a washing machine.

Heart murmurs can be graded from 1 to 6, with grade 1 murmurs being the mildest and grade 6 the most severe. The grade of the murmur doesn't necessarily correlate with the severity of the heart disease though. Also, not all heart diseases appear as a heart murmur at all and will be picked up in the rhythm of the heartbeat.

Depending on the grade of the murmur, our vets may advise that further investigations into the cause of the murmur are needed. This can take place with a blood test, a chest x-ray as well as a heart scan.

The most common heart disease we come across in cats is Hypertrophic cardiomyopathy or HCM. The disease is characterised by thickened muscle in the heart walls, which is known as hypertrophy. Due to this thickened heart muscle the heart chambers, particularly the ventricles, cannot pump a normal volume of blood as effectively. This causes a back pressure of blood and enlargement of the upper chamber (atrium). This change can lead to fluid build-up in the lungs (pulmonary oedema), and turbulent blood flow in the atrium which can cause clot formation.

Pedigree cats such as Maine Coons, Ragdolls, Persians, and British Shorthairs are most commonly affected, however, the condition is also very common in domestic shorthair/ longhair cats. HCM is also very common in cats who have been diagnosed with hyperthyroidism. Signs your cat may have heart disease include lethargy or reduced willingness to exercise or play, reduced appetite, increased breathing rate or laboured breathing, or sudden paralysis of both hindlegs which can be due to clot formation.

The most common treatments for HCM include diuretics to help remove any excess fluid build-up; ACE inhibitors which can help to regulate blood pressure and decrease the workload of the heart; and anticoagulants which can help to prevent clot formation.

With early diagnosis of heart disease, treatment may help to slow or delay its progression and help to maintain a good quality of life. However, unfortunately, many cats do not show clinical signs until the disease is very advanced, and are already in heart failure at the time of diagnosis, which carries with it a very guarded prognosis.


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