A 7-year-old spayed female Boxer weighing 42 pounds presented to the Cornell University Hospital for Animals for evaluation of weight loss despite a ravenous appetite for the past 6 months. The owners also reported diarrhea for the past 3 months, with approximately six episodes per day of pasty, yellowish-brown feces. The referring veterinarian had treated with Baytril, Metronidazole, Prednisone and Amitriptyline (the owners had recently lost another dog in the household and thought that depression may have been contributing to the weight loss) with no signs of improvement.