The nose consists of an outer part (the muzzle or nasal plane), and an inner part (the nasal cavity). The nasal cavity is split in two by a nasal septum. Tumours can occur on the muzzle, septum and nasal cavities.

Behaviour

Tumours located in the nasal cavity can be tumour types such as carcinomas, sarcomas, and rarely other types as well. Clinical signs include sneezing, nasal discharge, nose bleeds, sneezing episodes and/or changes in the shape of the nose and/or head. The tumour will grow inside the nose and involve several cavities, such as the frontal sinuses, maxillary sinuses and may even involve the eye sockets and brain cavity. For intranasal tumours, there’s a low rate of metastasis at diagnosis, although at the time of death, metastases are found in 40-50% of cases. If metastases occur, they’re mostly located in the nearby lymph nodes and lungs.

Prevalence

Tumours located in the nasal cavity are relatively rare (1-2% of tumours in dogs and cats).

The clinical signs can be varied, and include visual anomalies of the muzzle, discharge from the nose (mucus, blood), sneezing (episodes), gagging, and audible breathing. On clinical examination, the following changes may or may not be present: changes of the muzzle (depigmentation, swelling, abnormal growth), decreased air passage, pain, dental problems and/or swollen lymph nodes.

For intranasal tumours, the clinical signs are not very specific (purulent or mucous nasal discharge) and imaging is often necessary to detect the presence of the tumour. The symptoms become gradually worse and on average the diagnosis is only made 2-3 months after the first appearance of symptoms. A radiograph is not very specific but can indicate a mass and possibly also damage to the bones. A CT scan is most useful to estimate the real size, extension and location of the tumour, and hence is considered the best imaging tool for intranasal tumours. It also allows staging and planning for surgery/radiotherapy. An MRI scan may be needed, if involvement of the brain is suspected or confirmed. Radiographs, CT and/or MRI scans are taken under general anaesthesia as the dog has to lie perfectly still. The exact tumour type can be determined via tissue sampling, usually via endoscopy for intranasal tumours, or via fine needle aspirates (under ultrasound guidance), if the tumour is accessible enough. The result of the tissue sampling will help the veterinarian choose the most suitable treatment.

For tumours on the muzzle, various options are available: radiotherapy, resection of a part of the nose, hyperthermia, , cryosurgery, photodynamic therapy and electrochemotherapy.

For intranasal tumours, radiotherapy is the treatment of choice. Depending on the tumour type, different results have been obtained with chemotherapy or targeted therapy. Other options include immunotherapy, cryotherapy, photodynamic therapy, electrochemotherapy or endoscopic removal. Often multiple treatment options are combined. So depending on the tumour type, radiotherapy may be followed up with chemotherapy or targeted chemotherapy and combined with anti-inflammatory drugs.

For intranasal tumours, dogs generally live for about 3 months without therapy. With surgery, survival is between 3-6 months. With radiotherapy in early stages, most dogs have no tumour progression for years, whereas once there’s invasion of the bone of the eye socket or the brain/a mass deeper in the throat/a submucosal mass survival is between 6 months and 2 years. Prognosis however is very dependent on the tumour type. The risk of relapse is very high with all treatment modalities, meaning this is a management rather than a cure. In case of a relapse, the dog can receive additional radiation therapy sessions, although this increases the risk of long-term complications due to the increased total radiation dosage. The more advanced the tumour stage, the shorter the survival.