Standard protocol for splenic measurement is warranted to aid in interpretation when sonographically imaging the spleen of cats. The purpose of this study was to describe the appearance and size of healthy cat spleens, and to develop a standard method of evaluation. Data were obtained from 31 clinically healthy non-sedated cats with no sonographic abnormalities. The sonographic appearance of the spleen's relative echogenicity compared to the left renal cortex and the hepatic parenchyma was recorded. Splenic height was measured at three sites. Three measurements were determined at each site, and the mean value of these three measurements was determined and used for data analysis. A significance level of P <0.05 was used for analysis, which was performed using S-PLUS software (version 8.1). The mean proximal height of the spleen was 7.1 mm. The mean body sagittal height was 9.3 mm. The mean height of the tail of the spleen was 8.7 mm (95% confidence interval). The splenic parenchymal echogenicity was less than the left renal cortex echogenicity and greater than the liver in 17/31cats; less than the left kidney cortex and equal to the liver in 5/31cats; equal to the cortex of the left kidney and greater than the liver in 5/31 cats; equal to the liver and renal cortex in 2/31 cats; and less than the liver and kidney with the renal cortex less than the liver in 2/31 cats. The protocol recommended for consistent evaluation of the spleen in the cat includes three specific measurements.