Neuroendocrine tissues are tissues that have both nervous system and hormone-producing functions. They are found in a number of locations throughout the body. Tumors develop occasionally from neuroendocrine cells in the adrenal or thyroid glands. These can be benign or malignant. Even if benign, a growing tumor can disrupt nearby normal tissues and, in some cases, secrete excess hormone.

Chemoreceptor organs are derived from neuroendocrine tissue. They can detect very small changes in the carbon dioxide and oxygen content and pH of the blood, and they help regulate breathing and circulation. Tumors in chemoreceptor tissue usually develop principally in either the aortic body (found in the chest) or in the carotid bodies (found in the neck). Tumors of the aortic and carotid bodies are seen most often in brachyce-phalic breeds of dogs, such as Boxers and Boston Terriers. The tumors do not secrete excess hormone but may cause problems by placing pressure on the heart, blood vessels, and nerves.

Last full review/revision July 2011 by Deborah S. Greco, DVM, PhD, DACVIM; David Bruyette, DVM, DACVIM; Robert J. Kemppainen, DVM, PhD; Mark E. Peterson, DVM, DACVIM; Robert C. Rosenthal, DVM, PhD, DACVIM (Small Animal, Oncology), DACVR (Radiation Oncology)