In veterinary medicine, different results are found, depending on the tumour type: in hemangiosarcomas of the spleen and mammary adenocarcinomas of the breast, higher Ki-67 indices are associated with a poorer prognosis, whereas in canine apocrine gland anal sac adenocarcinomas no correlation was found regarding survival time [4,48,49]. This evidence concerns the gene MKI67 and neoplasm.