In the analysis of serum YKL-40 levels, dogs with multicentric lymphoma had a median YKL-40 level of 394.0 pg/mL (range: 146 to 1196 pg/mL), which was significantly higher than that of healthy dogs, whose median YKL-40 level was 218.6 pg/mL (range: 101.1 to 445.0 pg/mL) (p = 0.012) (Figure 1). Here, CHI3L1 is linked to lymphoma.