Colitis is an inflammation of the large bowel. Colitis can be acute or chronic causing diarrhea and small quantities of blood and mucus. Other signs can include depression, fever, weight loss, dull coat, and abdominal pain. Causes of Colitis include parasites, bacteria, fungus, colon polys and nervousness. Although few cases of colitis can be cured, the goal of therapy is to control the problem and reduce the inflammation helping your pet to enjoy a high quality of life. The best diet is high fiber such as Science Diet R/D.