AGE-RELATED-CHANGES IN THE FELINE CARDIAC SILHOUETTE

An exaggerated ''horizontal'' alignment of the heart (increased sternal contact) and tortuous, redundant aorta are often seen on thoracic radiographs of older cats. Eighty-five cats, divided into 3 age groups [young (6-15 months), middle aged (3-7 years), old (10-17 years)], were determined to be normal on history, auscultation, ECG, and echocardiogram. Lateral and VD thoracic radiographs were examined and measured for evidence of these changes. Forty percent of cats 10 years or older were found to have the horizontal cardiac alignment, and 28 % had the redundant aorta. These changes were not seen in Groups 1 and 2 of younger and middle aged cats. The angle between the heart and sternum in Group 3 (old) cats was significantly smaller than the same angle in younger cats. Systemic hypertension and hyperthyroidism, possible pathologic causes for this variation, were unlikely related to the cardiovascular changes due to the large number of older cats with this change, and lack of evidence of left ventricular hypertrophy.