Following the improvement of animal welfare, more and more people regard pets as families. With update and progress of the veterinary clinical medicine, pet's lifespan prolongs obviously. More senile diseases and neoplastic diseases increase unavoidly year by year. Traditional morphologic diagnosis methods couldn't satisfy current requirement. This project will apply histochemistry and immunohistochemistry methods to the diagnosis of pet animal neoplastic diseases. By establishing pet animal neoplastic diseases data bank, we can work together with clinical veterinarians to provide reliable diagnosis of neoplastic diseases and improve diagnosis of pet animal diseases. Hopefully, the pathological reserch of neoplastic disease on animals will be used as a model for human beings.