The majority of nasal tumors in dogs and cats are malignant. 

The most common clinical sign is nasal discharge. 

CT scans are much more sensitive than routine radiography for imaging nasal tumors and determining the extent of disease. 

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. 

What are Nasal Tumors?

• The majority of nasal tumors in dogs and cats are malignant. 
• The most common nasal tumors in dogs are adenocarcinoma, squamous cell carcinoma, undifferentiated carcinoma. 
• The most common nasal tumors in cats are lymphoma and adenocarcinoma. 
• Other tumors seen in both species include fibrosarcomas and other sarcomas.  Benign tumors include adenomas, fibromas, papillomas, and transmissible venereal tumors (TVTs in dogs only). 
• Older animals are more commonly affected, but nasal tumors can be found in animals of any age.

Clinical Signs

• 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 (ie no nasal discharge). 
• Anorexia and weight loss can accompany the respiratory signs.

Diagnosis

• Diagnosis of nasal tumors is made by identifying abnormal tissue on physical exam, radiography (xrays), 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 histologic (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.  Cats with lymphoma should also be tested for feline leukemia and FIV.

Treatment

• 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.  Lymphoma in cats should be treated with standard lymphoma chemotherapy protocols or radiation therapy.  Radiation therapy does not have the systemic side effects of chemotherapy, but may not be effective if the tumor involves other organs.

Complications

• 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.

Prognosis

• 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. 

References

• Nelson, Richard W. and C. Guillermo Couto.  Small Animal Internal Medicine.  Mosby, Inc.  St. Louis, 1998.
• Ettinger, Stephen J. and Edward C. Feldman.  Textbook of Veterinary Internal Medicine.  W. B. Saunders Company.  St. Louis, 2000.