Four dogs with similar respiratory signs were referred to Veterinary Medical Teaching Hospital, Seoul National University. The clinical signs observed in these cases were anorexia, nasal discharge, sneezing, epistaxis, ocular discharge, and exophthalmoses. The routine laboratory tests revealed leukocytosis in two cases. On the skull radiographs, soft tissue density filled nasal cavity with loss of turbinate detail and increased density in frontal sinuses were found in all cases. Lysis of nasal bone was seen in two cases. Lysis of zygomatic arch was seen in one case. On computed tomography scan images, asymmetrical destruction of turbinate and nasal septum, and the superimposition of a soft tissue mass over the turbinate with peripheral contrast enhanced effect were identified in all cases. Destruction of ipsilateral orbital bone and invasion to retrobulbar region were visualized in all cases. In addition, all cases had lysis of cribriform plate. Lysis of nasal bone and destruction of hard palate were seen in two cases. Swelling of submandibular lymph node and salivary gland was seen in a case. Invasion to brain was identified in a case. All cases were diagnosed as nasal adenocarcinoma by cytology with fine needle aspiration and curettage.