Colitis is defined as inflammation of the colon. The colon, also known as the large bowel or large intestine, is the end of a dog’s digestive tract. Waste products (feces) move from the colon through the anus out into the environment. Colitis can be caused by anything that inflames or irritates the large intestine. Some of the most common causes are bacterial and parasitic infections, trauma, allergies, dietary indiscretion and immune system abnormalities. High-strung, stressed, nervous dogs are particularly predisposed to developing colitis. The symptoms of this condition include diarrhea, intestinal cramping, nausea and pain. Defecating is uncomfortable, and affected dogs often squat and strain for prolonged periods of time while they try to relieve themselves. Dogs with colitis tend to have loose, unformed stools that may contain a mixture of mucus and blood. Fortunately, once the cause of colitis is identified, most dogs can be treated and return to their normal lives.