Apocrine Gland Anal Sac Adenocarcinoma

Canine apocrine gland anal sac adenocarcinoma (AGASACA) is a locally invasive, malignant neoplasm with paraneoplastic hypercalcemia and metastatic potential, commonly affecting middle-aged to older dogs, with certain breeds overrepresented. Pathogenesis involves aberrant proliferation of secretory epithelial cells with inconsistent expression of COX-2, VEGFR-2, PDGFR, KIT, EGFR, and other receptor tyrosine kinases. Clinical signs include perianal swelling, scooting, and systemic symptoms due to hypercalcemia. Diagnosis involves physical examination, cytology, and staging. Treatment typically involves surgery, often a closed anal sacculectomy, with potential complications such as wound dehiscence and rectal perforation. Lymphadenectomy is advised for metastatic lymph nodes. Multimodal approaches, including surgery and chemotherapy, are recommended for optimal management. The chapter discusses the treatment options for AGASACA in dogs, focusing on primary tumor removal, adjuvant therapy, and small-molecule inhibitors. It highlights the importance of reducing disease burden and obtaining a definitive diagnosis, as well as the potential benefits of genetic analysis and autologous cancer vaccines. The text also reviews the use of small-molecule inhibitors, such as toceranib and imatinib, in treating AGASACA, with a focus on their mechanisms of action and clinical outcomes.