Ruling out underlying medical problems is essential to the work up of any behavior problem. In this case-based learning segment veterinary behavior expert Dr. Christine Calder discusses the case of a 3 year old dog that presented for an evaluation of changes in behavior including resource guarding of her food and aggression towards familiar people, and whose underlying gastrointestinal problems were believed to be contributing to her behavior. Discussion includes the diagnostic work up, the medical and behavioral diagnoses, medical management, behavioral management and safety treatment plan, and the outcome. To earn CE credit access an evaluation after viewing the video in its entirety and clicking on the designated link at the very end of the video.