Heart disease

Hypertrophic cardiomyopathy (HCM) is a condition where the muscular walls of the heart become thickened, which affects how well it can perform. In some cats, this can progress into heart failure, as well as increasing the risk of things like serious blood clots. High blood pressure and hyperthyroidism are not the cause of HCM but can make things worse in a cat that already has mild to moderate underlying heart disease.