A 5-year-old male castrated Shepherd mix presented to the Cornell University Hospital for Animals (CUHA) Emergency Service on 8/7/17 for dependent edema, abdominal effusion, hyporexia to anorexia, intermittent vomiting, and a second opinion on a cardiac mass and gastrointestinal (GI) ulcers. Prior to presentation the dog had vomited for two days and became anorexic. The addition of facial swelling prompted his owners to bring him to a referral hospital for evaluation, at which time ascites was noted. Ultrasound revealed a cardiac mass and changes to the stomach consistent with gastric ulcers. The dog was hospitalized for two days with supportive care but did not improve. He re-presented to his primary care veterinarian on 8/7, where he was perceived to be in respiratory distress and was referred to the CUHA. On initial presentation, he was bright, alert, responsive, and his vital parameters (heart rate, respiratory rate, temperature) were all within normal limits. His physical exam revealed dependent edema extending from jowls to prepuce, and both an Abdominal and Thoracic Focused Assessment using Sonography for Trauma (AFAST and TFAST, respectively) showed ascites and a small amount of pleural effusion. A therapeutic and diagnostic abdominocentesis was performed and he was placed in the Intensive Care Unit (ICU) for stabilization. His initial problem list included: ventral pitting edema, bicavitary effusion, anorexia, vomiting, and suspect heart mass and GI ulcerations. He was presumptively diagnosed with third-spacing due to systemic vasculitis. Over the course of a month he did not improve despite treatment. Euthanasia was elected and he was diagnosed with a diffuse form of lipogranulomatous lymphangitis (a rare, severe form of inflammatory bowel disease) after a teaching necropsy was performed. This case emphasizes the clinical importance of understanding the pathophysiology behind effusions and the subsequent diagnostic steps that can be taken to help determine a cause for third-spacing.