There are several methods used to induce cancer in animals for medical experimentation. One common method is to use chemicals or substances that are known to be carcinogenic, or cancer-causing. These chemicals can be administered to the animals through their food or water, or applied topically to the skin.

Another method is to use radiation to induce cancer, this can be done by exposing the animals to ionizing radiation such as X-rays or gamma rays.

Another method is to use genetic engineering to create animals that are predisposed to developing certain types of cancer. This can be done by introducing specific genetic mutations into the animal's DNA that are known to be associated with the development of cancer.