Carcinoid tumors are small tumors of the gastrointestinaltract, that secrete serotonin. This is a naturally occurring neurochemical usually associated with sleep and memory functions. Carcinoid tumors are rare, slow growing neuroendocrine tumors formed by the endocrine cells of the mucosal lining of organs such as the stomach and intestine. These tumors secrete serotonin and histamine into the bloodstream along with a number of chemicals such as bradykinins and tachykinins which are responsible for tissue contraction. They primarily occur in dogs older than nine years and are usually found in the stomach, small intestine, colon, lungs, gallbladder and liver. Clinical signs may vary depending on the location and the degree of metastasis of the tumor. The size of the tumor and how it is interfering with the functionality of the organ will influence the symptoms and prognosis. The common symptoms include anorexia, vomiting, dyschezia, weight loss due to liver failure, and heart disease.
