Prevalence of hypertrophic cardiomyopathy (HCM) in feline population examined by the osservatorio italiano HCM felina

Hypertrophic cardiomyopathy (HCM) is the most common feline inherited cardiac disease and it is a major cause of morbidity and mortality. The Osservatorio Italiano HCM Felina was formed in 2008 by a network of clinicians, geneticists and breedings to monitor and study HCM in Italian cats. Since April 2008, 1308 adult cats, belonging to various breeds, including Maine Coon, Siberian, Norwegian Forest Cat, Ragdoll, Sphynx, British SH, Birmans and others have been prospectively enrolled. Recheck evaluations were performed in 287 cats. Each cat underwent a clinical examination, echocardiography, and blood collection for genetic testing (when appropriate) and storage in the Italian Feline Biobank. The disease status was defined by echocardiography according to established guidelines (left ventricular diastolic wall thickness<5.5mm = HCM negative, =5.5 but < 6mm = HCM equivocal, = 6mm = HCM positive). The prevalence of HCM in the population was 6% (74 cats); equivocal diagnoses were conferred on 4% (57 cats). These prevalences did not differ between breeds. The prevalence of HCM in the Italian feline population was lower compared to those reported by other investigators. Evaluation of data from the entire population demonstrated that left ventricular end-diastolic wall thickness and aortic diameter showed a weak positive correlation with body weight (p< 0.0001, r2<0.12 for all variables), suggesting that weight-dependent limits on wall thickness should be considered in cats as is currently practiced in dogs. The lower prevalence of HCM in Italian cat breeds compared with those examined elsewhere might be explained by different criteria for determining presence or absence of disease, differences in ages at which the subject were examined, or a selection bias by breeders in presenting cats they consider “normal”.