Case Description: A 6 year old castrated male chocolate Labrador Retriever presented to the Cornell's Orthopedic Service. A diagnosis of left cranial cruciate rupture prompted a tibial plateau leveling osteotomy. Post-operative complications included severe erosive gastritis and esophagitis. Clinical Findings: An esophageal endoscopy revealed multifocal to coalescing erythematosous circular lesions. The stomach contained severe multifocal hemorrhages to diffuse erosions and significant amounts of digested blood. The dog was diagnosed with severe erosive gastritis and esophagitis. Treatment and Outcome: Management included fluid and intravenous pressure maintenance, blood products, pain management, and gastroprotectants. The hematemesis resolved and the anemia and hypoproteinemia improved before discharge. Clinical Relevance: Non-steroidal anti-inflammatory drug administration was strongly suspected as a cause for the erosive gastritis. Although cyclooxygenase selectivity is unclear in canines, inhibition of either form could lead to gastric disturbances. Concomitant administration of otic steroids and oral non-steroidal anti-inflammatory drugs may have exacerbated side effects.