Comparison of ultrasonographic renal measurements in kittens up to 3 months of age and young cats

Abstract

Objectives This study aimed to evaluate renal measurements by B-mode ultrasound in kittens during their first 3 months and compare them with those of young adult cats. Methods Forty-eight healthy mixed-breed cats (24 males and 24 females) were enrolled in this study. The cats were divided into six age groups: groups 1–5 (kittens) and group 6 (young adult cats). Each kidney was examined using B-mode imaging and the following measurements taken: renal length (RL), renal height (RH), renal width (RW), cortical thickness (CoT), medullary thickness (MdT) and corticomedullary ratio (CMr). The ratio and correlation of RL to aortic diameter (AoD) and the length of the fifth/sixth lumbar vertebrae (LLV) were also determined. Results Among groups, there was a statistically significant difference between RW, renal volume (RV), CoT, MdT and CMr. The smallest renal dimensions were obtained in the youngest kittens (up to 10 days of age), including RL (1.84 ± 0.40 cm), RH (1.14 ± 0.17 cm), RW (1.25 ± 0.20 cm) and RV (1.47 ± 0.68 ml). A strong correlation was observed between RL:AoD and RL:LLV, allowing for linear regression equations and reference intervals for RL:AoD and RL:LLV to be created for each age group. Conclusions and relevance B-mode ultrasound showed that renal measurements in kittens differed from those in young adult cats, and that the renal dimensions, renal CoT and CMr increased with the growth of the cat. The RL-LLV ratio is a reliable method for measuring RL according to age group.