The work reports a rare case of canine two primary malignant tumours concurrent with one benign tumour occurring within a single organism. Soft palate malignant melanoma with metastases to the regional lymph nodes and internal organs was classified as the index tumour, while thyroid carcinoma was defined as incidentaloma. The third tumour recognised was a large lipoma located in the abdominal cavity. The presented case proves that in the animal organism affected with a malignant tumour, other tumours may develop.