A case of odontogenic myxoma in an old Doberman bitch involving the periodontal region of the mandible was recorded. Grossly, the tumour mass was soft and slimy, having brownish-black foci on cut surface. Histopathologically, the tumour predominantly consisted of mesenchyme-like cells with prominent nuclei and nucleoli. The tumour had abundant ground substance, rich in acid mucopolysaccharides.