MKI67 and carcinoma: However, Ki-67 serum concentrations in dogs with malignant NDs in the present study (2 ng/mL with an IQR of 1–4.5 ng/mL for carcinomas and 1–6.8 ng/mL for sarcomas) were not as high as reported for dogs with other neoplastic diseases with a median serum Ki-67 concentration of 243 pg/mL (IQR: 0–7,500 pg/mL) (19).