Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

162 Small Animal Radiolo g y and Ultrasono graphy
Fig. 2-140 A 9-year-old neutered
female Siamese cat had difficulty
breathing. An M-mode echocardiogram
through the aorta (AO) and
left atrium (LA) revealed a severe
dilation of the left atrium.
Diagnosis: Left atrial dilation secondary
to unclassified cardiomyopathy.
Fig. 2-141 An M-mode echocardiogram
through the left ventricle of the
same cat as above revealed normal
parameters. Diagnosis: Unclassified
cardiomyopathy.
marked left atrial or biatrial dilation, with a normal left ventricular diameter and wall
thickness. 416 Other changes may include normal to thickened myocardium and normal
to slightly decreased fractional shortening and ventricular diameter (Fig. 2-141).
Distortion of the left ventricular chamber and an irregular and highly echogenic endocardium
may be seen. Mitral valve regurgitation may be demonstrated with Doppler
studies in these cases.
H Y P E RT H Y R O I D H E A RT D I S E A S E
Many cats with hyperthyroidism will have cardiomyopathy also. The classic echocardiographic
changes include left ventricular hypertrophy, left atrial and ventricular dilation,