Acute onset of diarrhea in horses is a medical emergency. It is very important that horses are quickly evaluated and treated to prevent profound dehydration and cardiovascular problems. Diarrhea in horses can be caused by many different types of health problems that cause the horse’s colon to become unable to function properly (i.e. the colon cannot absorb the intestinal fluid as it normally would). Common causes include infections with Salmonella or Clostridium bacteria, sand ingestion, parasites, toxicity due to the administration of NSAIDs (bute or flunixin), secondary to administration of antibiotics, ingestion of cantharidin (a toxin in blister beetles found in alfalfa hay), cancer, or inflammatory bowel disease. Auburn offers complete care for horses with diarrhea. These patients are housed in a specialized isolation care unit to prevent the spread of infectious diseases to the other patients, and are treated hourly as prescribed by the attending equine internal medicine specialist.