A 13-year-old female lion underwent a simple mastectomy for a rapidly growing abdominal mass, confirmed as mammary adenocarcinoma after histopathological examination. Mammary tumors are common in domestic cats but less frequently reported in African lions. This report presents the first documented case of mammary adenocarcinoma in an African lion in South Korea. The mass was successfully excised through stable anesthesia and surgery. This report adds to the limited literature on mammary tumors in large felids and discusses the need for tailored management strategies.

• Jihyun Park(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Jungnok Ryu(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Jimin Jeong(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Chaeree Byun(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Victoria Tay Kymm(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Jinseok Son(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Jongwan Chang(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Yoonho Roh(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Dongbin Lee(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea) Corresponding author
• Yungduck Lee(Department of Pet, Division of Welfare and Health, Busan Women's University, Busan, 47228, Korea)