As ultrasound equipment with Doppler applications is being widespread, quantitative analysis of the intrarenal arteries Doppler spectra has been quickly extrapolated to veterinary medicine. However, there is no agreement between authors about the site of the measurements and the value of the upper threshold of the RI in dogs and cats. The aim of this study was to verify the influence of age, sex and body weight on the intrarenal RI of dogs and cats, as well as determining the qualitative character of the Doppler spectra. Additionally, average difference of the RI between kidneys (delta RI) was calculated. All measurements were performed in the interlobar renal arteries of manually restrained animals, accordingly to the overall standards of the procedure of Doppler ultrasound examination. In total, 44 dogs and 31 cats were examined. Mean RI±SD was 0.64±0.04 in dogs and 0.6±0.04 in cats. An average, positive correlation between animals age and the RI was found. No relationships of the sex with the RI and body weight of the dogs with the RI were observed. In contrast to dogs, waveforms of 16% of cats did not present a double systolic peak. In conclusion, the authors consider 0.71 and 0.68 as an upper normal limit of RI measured in interlobar renal arteries in dogs and cats, respectively.

Key words: Cats, Dogs, Doppler Ultrasonography, Renal Interlobar Arteries