by Dr. Gail Mason, DVM, MA, DACVIM
Nasal tumors are a type of cancer that result from uncontrolled growth of abnormal (glandular) cells lining the nasal cavity or sinuses. Though considered uncommon in dogs, the most prevalent nasal tumor is an adenocarcinoma. It is most commonly diagnosed in medium to large breed dogs that are senior in age. Nasal tumors can be difficult to detect as they are hidden away within the nasal cavity and progress slowly over time. The average patient diagnosed with a nasal tumor has been symptomatic for at least 3 months.
Nasal discharge: is the most common early symptom of
a nasal tumor. The discharge may contain mucus, pus, and /or blood. Most often, the discharge is noted from only one nostril. Droplets of discharge found on bedding is an early clue.
Excessive sneezing: is not
always present with nasal tumors. In fact, sneezing is more commonly attributable to allergies or infections. Any persistent sneezing, unresponsive to symptomatic relief should prompt further investigation.
- Snoring: tumors of the nasal cavity are usually locally destructive. As they slowly enlarge, they can erode the bone and tissues around them. Eventually, they can partially or fully obstruct one or both sides of the nasal cavity.
Progressive "snoring" which is particularly audible when the dog is sleeping can be associated with nasal tumors. Some dogs adopt "mouth-breathing" to compensate for this.
- Bleeding: is common in more advanced nasal tumors but does not result in an automatic diagnosis. It is a concerning symptom and should be investigated promptly. Tumors tend to have abnormal, fragile blood vessels which can bleed intermittently. More rarely, the bleeding can be profuse. Other causes of bleeding from the nose include fungal infections, bacterial infections, dental infections, foreign material lodged within the nasal cavity, and bleeding disorders.
- Rubbing face: dogs may experience some discomfort from the presence of the tumor and may rub their faces on the ground or other surfaces and may also paw at their faces.
Facial deformity: As nasal tumors gradually expand, they can distort the facial muscles and bones. Swelling of the face, muzzle, or near the eyes can be the result of advanced
- Seizures: (uncommon) can occur as a result of a nasal tumor's invasion into the area of the brain. Other changes in the dog's behavior can include lethargy, aggression, or circling
behaviors. It is important to remember that these symptoms are NOT diagnostic for nasal tumors. In fact, severe fungal infections (acquired through the environment) can mimic many of the signs of a nasal tumor.
- A diagnostic investigation by your veterinarian or a veterinary specialist would include a full medical history and screening blood work to assess overall patient health. Radiographs (X-rays) of the skull can provide important clues to the diagnosis. Nasal tumors often demonstrate destruction of the fine bony architecture within the nasal cavity and/or erode surrounding bone. In order to be useful, these radiographs must be taken under deep sedation or anesthesia for proper positioning.
Rhinoscopy is examination of
the nasal cavity using a very small fiberoptic Instrument. Much of the nasal cavity can be visualized, though the sinuses within the dog's skull cannot be reached in this manner. At least 85% of nasal tumors are in the "muzzle" portion of the sinuses and therefore amenable to rhinoscopy to procure a tissue biopsy.
CAT (CT) Scan
A CT scan is an extremely useful and detailed imaging modality to evaluate the skull and nasal cavity in dogs. It is particularly useful in diagnosing tumors that are far back in the nasal cavity and/or those that are within the frontal sinuses of the dog's skull. Ideally, these two procedures are combined to enable a targeted biopsy procedure.
There are treatment options for dogs with nasal tumors that can result in an extension of good quality of life. Currently, there is no cure for such tumors and untreated dogs have a median survival time of about 95 days after diagnosis. Dogs who receive treatment for their tumor average 6-18 months. Surprisingly, surgery is not a recommended option for nasal tumors. It is impossible to remove the entire tumor, and it does not appear to lengthen or improve the patient's life.
Radiation therapy as the sole treatment modality has become a therapy of choice for canine nasal tumors. It has the advantage of treating the entire nasal cavity, including bone, and its use has been associated with great improvement in survival. While the term “radiation" invokes negative images for most pet owners, it is an excellent therapy and well tolerated by dogs. They
do not suffer radiation sickness as humans do and usually only have
mild inflammation of the oral cavity. Chemotherapy has not traditionally had a place in the treatment of nasal tumors, but more recently, it has been found that tumors can be responsive to certain agents to extend good quality of life. As with radiation therapy, dogs tolerate these treatment modalities extremely well. For those who elect to have their pet treated, very few halt therapy due to perceived poor quality of life. New treatments are entering the veterinary market at an ever-increasing rate. We are gaining on this and many other tumors!