What are Nasal Tumors?
Nose cancer (or nasal adenocarcinoma) occurs when too many cells in the animal's nasal and sinus passages come together. The disease progresses slowly and occurs both in dogs and cats. Studies have shown nose cancer is more common in larger animal breeds than in smaller ones, and it may be more common in males than females. Options exist when the disease is caught early and aggressively treated.
In some cases, chronic inflammation of the nose (rhinitis) leads to proliferation (hyperplasia) and formation of polyps in the nose or throat. These are not cancerous but may need removal. The chronic inflammation is often due to infections with viruses, bacteria and/or fungi and also occurs in animals with a tendency to allergies (atopic animals). Some chronic infections predispose to cancer.
Most cancers originate from the lining of the nose (epithelium). Benign tumors (adenomas) are rare but if they are surgically removable, they are curable. Malignant tumors (carcinomas) are more common with many different types. All of them invade and destroy adjacent structures. They rarely spread (metastasize) elsewhere in the body. A few carcinomas originate from hormone producing neuroendocrine cells. These may invade the brain.
A few cancers originate from the supporting connective tissues of the nose (cartilage, fibrous tissue or bone). These sarcomas tend to be less aggressive than carcinomas but can rarely be removed surgically. They may also recur following surgical removal.
Non-cancerous proliferation of the lymph tissue (which includes the tonsils) forms nodules that physically obstruct air flow. These are common and probably the result of chronic or multiple infections. Cancer of the lymph tissue in the nose and throat is rarer but occurs in cats.
How common are nasal cavity tumors in dogs?
Tumors in the nasal cavity and paranasal sinuses are not very common and account for approximately 1% of all tumors in dogs. However, approximately 80% of these tumors are malignant and have a poor long-term prognosis. The average age of dogs with this disease is about 10 years and medium to large breeds may be at higher risk
- The most common clinical sign is nasal discharge. The discharge can be serous, mucoid, mucopurulent, or hemorrhagic. One or both nostrils can be involved, however if bilateral nasal discharge is seen, one side is usually worse than the other. Many animals start with discharge from one nostril, which progresses to both nostrils.
- Sneezing and decreased or absent air flow through one of the nares may also be seen.
- Deformation of the facial bones, hard palate or upper dental arcade may be seen.
- If the tumor grows into the cranial vault, neurologic signs can be seen.
- Tumor growth into the orbit can cause protrusion of the eye or inability of the eye to be gently pushed back into the orbit. Neurologic signs and ocular abnormalities are rarely the only signs seen (i.e. no nasal discharge).
- Anorexia and weight loss can accompany the respiratory signs.
- Diagnosis of nasal tumors is made by identifying abnormal tissue on physical exam, radiography (x-rays), CT scan, fine needle aspirates of the mass or areas of facial deformity, or rhinoscopy with biopsies of the abnormal tissue. Biopsies should be obtained in all animals for histological (microscopic) confirmation.
- A definitive diagnosis often requires repeated evaluation, especially in dogs, because, unlike cats, they do not develop chronic nasal inflammation caused by viruses.
- CT scans are much more sensitive than routine radiography for imaging nasal tumors and determining the extent of disease.
- Thoracic radiographs should be evaluated for spread of cancer to the lungs, although lung metastases are uncommon.
- In the case of lymphoma, bone marrow aspirates and abdominal radiographs or ultrasound should be evaluated.
A pollutant-filled environment is a known cause of nose cancer in dogs.
Pathology reports identify most canine nasal tumors as carcinomas. Most of them are respiratory adenocarcinoma followed by squamous cell carcinoma and a few miscellaneous or undifferentiated carcinomas.
About one third of nasal cavity neoplasia in dogs are sarcomas, with fibrosarcoma being most common followed by chondrosarcoma, osteosarcoma, lymphoma, and then other miscellaneous and undifferentiated sarcomas.
- Benign tumors should be surgically excised.
- Treatment options for malignant tumors include surgical excision, radiation therapy, chemotherapy, or a combination of these therapies.
- Radiation therapy is the treatment of choice.
- Surgery alone does not result in prolonged survival times. A recent study indicated that a combination of surgery and radiation therapy results in longer survival times if the pet has a sarcoma tumor in the nasal cavity.
- Chemotherapy can be attempted when radiation therapy has failed or is not a viable option. Radiation therapy does not have the systemic side effects of chemotherapy, but may not be effective if the tumor involves other organs.
- Recurrence of the tumor in most cases is expected.
- Chronic nasal discharge and recurrent infection in the nasal cavity is a common problem following radiation and surgery of the nasal cavity, thus intermittent treatment with antibiotics may be needed.
- Complications of radiation therapy include: radiation-induced mucosal inflammation in the nasal cavity (seen as congestion, increased mucous production and bloody nasal discharge); oral inflammation (seen as increased salivation, oral pain, and bad breath); skin reactions; ocular manifestations (conjunctivitis and eyelid irritation, decreased tear production, corneal ulceration, cataracts, nasolacrimal duct obstruction, retinopathy, and optic nerve injury; and a transient central nervous system syndrome (seen as disorientation and lethargy).
- A temporary complication of surgery may be air that develops under the skin (subcutaneous emphysema) which usually resolves within two to three weeks. Dogs that have had a nasal tumor removed will not have any normal turbinate bones left within the nasal cavity, therefore chronic nasal discharge is not uncommon.
- Persistent weight loss, anorexia and weight loss, neurologic signs, and labored breathing are common complications of nasal tumors, which lead to euthanasia.
- The prognosis for untreated malignant nasal tumors is poor, with survival times of only a few months after diagnosis.
- Radiation therapy can prolong survival and improve quality of life in many animals.