The causes for weight loss in horses are numerous and can involve many body systems. This discussion is confined to diseases of the GI tract. Protein loss may or may not be associated with weight loss. The disorders commonly associated with either of these signs are neoplasia, inflammatory bowel disease, and toxicosis from treatment with NSAIDs.
Last full review/revision September 2013 by Allison J. Stewart, BVSC (Hons), MS, DACVIM-LA, DACVECC