Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. Maine coon is one of the breeds where the disease is overrepresented. Studies have shown that HCM is inherited as an autosomal dominant trait in Maine Coon cats. This finding has led to cardiac screening using ultrasound in the breed. The results of the screening are used in a national breeding program constructed to reduce the spread and incidence of HCM in Maine Coon cats.