Fig. 3

The serum concentration of some analytes at different stages of the dog’s life. Comparison of the mean (red line) (A) urea and (B) creatinine levels between groups of clinically healthy dogs of different ages: group I (n = 35, 4–8 wk), group II (n = 48, 9–24 wk), group III (n = 21, 25–52 wk), and group IV (n = 71, > 52 wk). Horizontal blue dotted lines represent the RIs for adult dogs with a 90% CI (see Table 1 for age-specific reference intervals). Means that do not share a letter are significantly different (p < 0.05)