Nasal tumors in dogs are not very common – they account for about one percent of all tumors in dogs. However, about 80% of nasal tumors found in dogs are malignant (cancerous).
Several tumor types can be found in the dog’s nasal cavity, which is a large air-filled space above and behind the nose.
The most frequently occurring nasal tumor in dogs is squamous cell carcinoma, although fibrosarcoma and many others can also occur.
All of these tumors arise within the inside of the nose or the sinuses. Both carcinomas and sarcomas are locally invasive. It means that they are aggressive, fast developing, and can invade vital surrounding structures such as the throat.
Occasionally, some tumors also metastasize (spread) to more distant areas of the body.
Up to 30% of nasal tumors in dogs will spread to the lungs, but this usually happens long after the tumor first forms.
These nasal tumors can also spread to the lymph nodes, the bones, the liver, the brain, and rarely to other areas of the body.
Causes of Nasal Cancer in Dogs
The exact cause of this canine cancer is not known. But it appears that certain breeds (e.g. the Collies) are more predisposed to nasal tumors than others.
Environmental airborne carcinogens (cancer-causing agents), such as cigarette smoke, fume from kerosene heaters, and car exhaust, are also risk factors that can increase the risk for nasal cancer in dogs.
Age is a risk factor – Older dogs (average age 10 years) are at higher risk of developing nasal cancer.
Symptoms of Nasal Cancer in Dogs
Some typical symptoms of nasal cancer in dogs include:
- Nasal Discharge: One typical symptom is a greenish-yellow nasal discharge (most commonly from only one nostril). Sometimes the discharge can be bloody.
- Respiratory Symptoms: A dog with nose cancer will also show respiratory symptoms, such as excessive sneezing. Unfortunately, especially at its early stage, many vets may misdiagnose sneezing as something less serious such as allergies. In addition, the dog will most likely snore and snort while sleeping and his breathing may be labored and noisy as well. The dog may also show symptoms such as coughing and gagging.
- Bad Breath: As the tumor develops inside your dog’s nasal cavity, you may notice a foul smell from your dog’s nose and he may also have bad breath.
- Facial Deformity: Also, as the tumor continues to grow, it causes a visible swelling on one side of your dog’s face. The nose also looks deformed. If the tumor grows upward towards the eye socket, your dog may have a bulging eye. Your dog may also have eye discharge due to the tumor obstructing the tear ducts.
As you can imagine, nasal tumors can a lot of discomfort and pain to a dog. To alleviate the pain, the dog may rub his face on the couch, his bed, or the carpet. He may also try to lick and paw at his nose.
Diagnosis of Dog Nasal Cancer
A vet will conduct blood tests and physical examinations including checking for facial deformity and nasal passage blockage.
To definitively confirm the type and malignancy of the tumor, the vet usually performs a tissue biopsy.
He also uses CT scan to evaluate the extent of tumors in the nasal cavity. He will also take chest x-rays to determine if the cancer has metastasized to the lungs.
Treatment of Nasal Cancer in Dogs
In addition to addressing the immediate issues (e.g. pain, nasal discharge, etc.), the vet will look at various treatment options available for the dog patient. These options include:
Conventional treatment of choice for nasal tumors in dogs is radiation.
Radiation cannot cure the dog of nasal cancer. The goal is to shrink the tumor in order to increase lifespan and keep a good quality of life for the dog.
Radiation therapy is available only in select cities and veterinary schools. (In the USA, the University of Wisconsin Veterinary School has the most precise radiation for nasal tumors.)
For radiation to be most effective and successful, it should be combined with CT scans which are capable of locating problem areas even at the back of the sinuses in the nasal cavity (areas usually overlooked by x-rays).
For most nasal tumors, radiation therapy by itself can increase survival by one year in about half of the dogs treated.
Some studies showed that one dog in four will live 2 years following radiation treatment.
Recently, there is a new treatment plan for nasal tumors in dogs which includes radiation therapy every weekday for 3 weeks, along with a chemotherapy drug, cisplatin.
The cisplatin is contained in a sponge-like material which is surgically implanted in the muscle. The sponge-like material slowly delivers the drug into the bloodstream and works on the tumor over the 3 weeks of radiation.
The approximate survival time using this treatment plan is 580 days.
If the tumor is located close to the front of the muzzle, surgery, either alone or in combination with radiation, may be possible to remove the tumor.
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