In this retrospective study, the prevalence of atrial septal defects (ADs) in dogs and cats was determined with echocardiography and color-flow Doppler ultrasonography. Between 2001 and 2005, 414 animals were diagnosed with congenital heart disease (CHD), and ASD was diagnosed in 156 of them (37.7%). The most common type of CHD was mitral dysplasia-ASD was the second most common abnormality. The most common dog breed affected was the boxer (36/113), and the most common feline breed was the domestic shorthair (30/43). In 111 of the 156 animals, ASD was found incidentally while echocardiography was being done for a cardiac complaint or for a prepurchase, prebreeding, or preanesthetic workup. The most common clinical sign was a systolic heart murmur heard over the left heart base. Other signs included exercise intolerance, cyanosis and syncope, dyspnea, and cough. Animals with a systolic heart murmur over the left base had a significantly larger ASD. In this study, ASD was more commonly found than previously suspected.

COMMENTARY: This large retrospective study from the National Veterinary School of Alfort, France, reports the unexpected finding that atrial septal defects (ASD) in dogs and cats were the most common congenital heart disease (CHD) following mitral dysplasia, accounting for more than one third of canine and feline CHD. It is likely that ASD also has been historically underrecognized in the U.S. pet population, where the incidence has been reported from 0.7% to less than 10% of CHD in dogs and cats. Echocardiography has become widely used in small animal practice in recent years, and a more detailed epidemiologic picture of CHD in pets in this country will emerge as a result.

Retrospective study of 156 atrial septal defects in dogs and cats (2001-2005). Chetboul V, Nicholle A, Sampedrano CC, et al. J Vet Med 53:179-184, 2006.