If a vaccine is to protect the intestines and other mucous membranes
in the body, it also needs to be given through the
mucosa, for example as a
nasal spray or a liquid that is drunk.
In dogs, they often develop from carcinomas of the mammary glands, thyroid, bronchopulmonary epithelium, kidneys, chemoreceptor cells,
nasal mucosa, squamous epithelium of the skin, prostate, pancreas, adrenal cortex, and salivary glands.