Background Primary hypertrophic cardiomyopathy (HCM) is the most common feline heart disease and has been demonstrated to be inherited in some breeds. However, few studies have compared HCM phenotypes and survival according to breed. Objectives To compare epidemiological characteristics, clinical findings, left ventricular (LV) geometric patterns, and survival in several breeds of cats with HCM. Animals Three hundred and forty-four cats from 5 different breeds (Persian, Domestic Shorthair [DS], Sphynx, Maine coon [MC], and Chartreux) with primary HCM diagnosed by conventional echocardiography. Methods Retrospective study. Cats were classified according to breed and clinical status. Results Age at the time of diagnosis was lower (P similar to 001) in MC (median age, 2.5 similar to years) and Sphynx (3.5 similar to years) than in other breeds (OB), ie, 8.0, 8.0, and 11.0 similar to years for DS, Chartreux, and Persians, respectively. The prevalence of LV outflow tract obstruction was higher (P similar to 001) in Persians (23/41; 56%) than in OB (115/303; 38%). Age at the first cardiac event was lower (P similar to 01) in MC (median age, 2.5 similar to years) than in OB (7.0 similar to years). All cats surviving similar to 15 similar to years of age were DS, Persians, or Chartreux. Sudden death (representing 24% of all cardiac deaths) was observed only in 3 breeds (DS, MC, and Sphynx). Conclusion and Clinical Importance As in humans, feline HCM is characterized by marked phenotypic variability with several breed-dependent features regarding epidemiology, LV geometric patterns, and clinical course (ie, age at diagnosis, 1st cardiac event, and cause of death).
