Creatinine is produced by muscle metabolism as a creatine product, being totally excreted by renal route and widely used as an indicator of renal function in mammals. The aim of this study was to evaluate the effect of body condition indicators on the serum creatinine concentration. We evaluated 27 animals, 9 males and 18 females, aged 1 to 12 years, without clinical complaint. Data on weight, body condition score (BCS),canine body mass index (CBMI) and serum urea and creatinine concentrations were analysed. The mean creatinine concentration was 0,97 ± 0,26 mg / dL and urea 41,6 ± 16,5 mg / dL. The majority of the animals had BCS classified as ideal, with a mean of 5,3 ± 1,4 (range of 1 to 9) and mean CBMI of 14,5 ± 3,5. Subsequently the results were grouped into four categories according to weight, P1 (0 to 10 kg), P2 (11 to 20 kg), P3 (21 to 30 kg) and P4 (above 30 kg). There was a significant effect (p <0,05) of the weight class on the creatinine concentration, with lower values in P1 and a strong positive correlation of creatinine with the IMCC (r = 0,66, p <0,001), weight (r = 0,71, p <0,001) and height (r = 0,73, p <0,001). Therefore, in animals with an ideal body score, weight can be used as a criterion for classification of animals for the interpretation of the effect of body mass on the creatinine concentration and it is suggested the possibility of using reference values appropriate to the weight of the animals.
