Nose Cancer in Dogs

A dog’s nasal cavity is divided into two chambers (each made up on turbinate bones and paranasal sinuses) by a cartilaginous septum and extends into the two nostrils you see at your dog’s snout. The front of your dog’s nasal cavity handles respiration while the back part handles smell and taste.  The nasal cavity and paranasal sinuses are a complex network, and a cancerous tumor obstructs your dog’s breathing and causes significant other complications.

Nose cancer is an aggressive cancer more commonly found in older dogs, dogs with longer snouts, and dogs living in urban areas. Two-thirds of all nasal tumors are carcinomas, which form in the lining of the nose, and about one-third are sarcomas, which form in the cartilage, bone or connective tissue within the nose. A nasal tumor may also be lymphoma; however, this is rare. It can be treated if caught early, but nose cancer is by definition malignant, with a high frequency of metastasis to the lungs, skull cavity, or lymph nodes.

• Epistaxis (bloody nasal discharge)
• Mucous or pus in nasal discharge
• Sneezing
• Dyspnea (shortness of breath)
• Stertorous breathing (labored, noisy breathing)
• Anorexia
• Seizures
• Facial deformity
• Visible pain around nose
• Excessive ocular discharge

The exact cause of the cancer is not known, although it is correlated with certain risk factors. The most telling is an elevated risk in dogs living in urban areas, which suggests that exposure to pollutants, smoking, and fossil fuel combustion byproducts increase a dog’s risk of developing nose cancer.

The veterinarian will take tissue samples from lymph nodes in order to analyze for cancerous cells and detect possible metastasis. The nasal bacterial culture will be harvested and analyzed. In addition to the nasal bacterial culture, a rhinoscopy, or examination of the nasal passages, will be completed. Further, a combination of X-rays, computed tomography (CT) scans, and radiographic scans will be taken in order for the veterinarian to identify and diagnose the tumor, the extent of its proliferation, and to see if it has spread. An additional tool for diagnosis might be the biopsy of the cancerous growth for microscopic analysis by a laboratory pathologist.

Because adenocarcinoma advances so rapidly, it is typically very advanced at the time of diagnosis. For this reason, getting treatment as soon as possible increases your chance of survival. With a positive diagnosis, the veterinarian may refer you and your dog to a veterinarian oncologist. An oncologist specializes in treating tumors, and will be able to best advise you on your dog’s prognosis and help you make decisions regarding treatment.

Surgery

Adenocarcinoma is not amenable to surgery, due to the complex nature of your dog’s nasal cavity and the fact that the tumor is close to the brain and eyes. Therefore, the risk of complication outweighs benefits. In rare cases, rhinotomy, or an incision into the nose to remove the tumor, is attempted; however, success rates have not been encouraging, and rhinotomy correlates with significantly reduced survival time, average between three to six months.

Radiation and Chemotherapy

At this time, radiation therapy and chemotherapy have not proven effective at treating adenocarcinoma. The good news, radiation therapy is still considered an option to prolong life and relieve pain. Depending upon your dog’s tumor, you may consider one of the following options for radiation therapy:

• Stereotactic Radiosurgery delivers a high dose of radiation targeting the center of the tumor and is a one-time treatment designed to minimize damage to tissue surrounding the tumor.
• Stereotactic Radiation Therapy delivers up to three smaller doses at different times in order to further minimize the risk of damaging tissue around the tumor. This involves multiple visits to a radiation specialist as opposed to one and is used when a tumor is located dangerously close to essential structures such as your dog’s brain and eyes.

When considering radiation therapy, it is important to discuss the risks of possible side affects with the veterinarian, which can include inflammation, runny nose, skin shedding, atrophy, hemorrhage, degeneration, brain necrosis, seizures, optic nerve degeneration, fibrosis and bone collapse.

Untreated adenocarcinoma is very deadly, and affected dogs typically die within two to seven months of diagnosis. The median survival time of dogs administered with radiation therapy is eight to twenty months.

If your dog undergoes radiation therapy, be sure to carefully monitor symptoms and follow up with the veterinarian as scheduled and whenever symptoms warrant. Some side affects are treatable with antibiotics or other treatments; however, some of the most severe side affects are non-treatable.

The most critical task is keeping your dog comfortable. To ease pain, anti-inflammatories, pain medication, and sleeping pills may be prescribed. In serious cases, with a poor prognosis and debilitating pain, euthanasia may be considered as the best option.