Ceruminous gland carcinoma arises from the wax-producing glands (ceruminous glands) lining the external ear canal. It is the most common malignant tumour of the canine ear canal. Chronic ear infections (otitis externa) may serve as a predisposing factor, as the ongoing inflammation is thought to promote abnormal cell growth over time. The tumour's location within the ear canal often delays diagnosis, as early signs — such as ear discharge, head-shaking, or a foul odour — can be mistaken for a simple ear infection. By the time of diagnosis, the tumour may have invaded the deeper structures of the ear, including the bony bulla (the chamber behind the eardrum). Treatment typically requires total ear canal ablation with bulla osteotomy (TECA-BO) — complete surgical removal of the ear canal combined with opening and cleaning of the bony chamber behind the eardrum.