Canine anal sac adenocarcinoma is often already metastatic at presentation (sublumbar lymph nodes and more rarely to other sites); paraneoplastic hypercalcemia is also frequent. Surgical candidates are those with the primary tumor and metastasis not beyond the sublumbar lymph nodes; postoperatively, a survival time of 19-24 months or more may be expected when no sublumbar lymphadenopathy is detected on presentation; adjuvant chemotherapy may also be useful. Feline anal sac adenocarcinoma is rare and both metastasis and hypercalcemia are unusual while local recurrence represents the main reason of death/euthanasia.