Ultrasonographic (US) assessment of the renal size can provide useful clinical information, in combination with other US parameters. The aims of this study were to establish an US measurement of kidney-to-vertebral body (L5 and L6) ratio to estimate the renal size in cats, and to assess the impact of sex and gonadal status on the US measurements of the kidneys (K), vertebral bodies (VB) and ratios.
Sixty cats (19 intact males, 12 neutered males, 17 intact females, and 12 neutered females) were included. The cats were divided into two sex and gonadal status groups (male and female, and intact and neutered respectively). Renal and VB (L5 and L6) length measurements were performed on the longitudinal US images. Two different ratios were obtained K/L5 and K/L6.
The K and VB length was influenced by sex, having males cats longer K and VB (P< 0.05) than female cats. The VB and K were longer in neutered cats. However, the VB was influenced by the gonadal status (P< 0.05), while the renal length was not influenced by it. The K/L5 and K/L6 ratios were not influenced by sex and gonadal status.
In conclusion, the US K/L6 length ratio obtained: 1.81 ± 0.20 (1.76-1.86) is a useful and practical method for evaluating the size of the feline kidney and was not influenced by sex or gonadal status of the cats. As an alternative the K/L5 ratio: 1.79 ± 0.18 (1.74-1.84) can be obtained, if it is not possible to determine the K/L6 ratio.