What is a nasal tumor? 
A nasal tumor is a type of cancer that results from the disorganized uncontrolled production of cells that line the nasal airway. In dogs, the most common nasal tumor is nasal adenocarcinoma. Nasal adenocarcinomas originate from the glandular cells (e.g., sebaceous glands) in the nasal cavity. In cats, the most common nasal tumor is nasal lymphoma.
What causes this cancer?
The reason why a particular pet may develop this, or any, cancer is not straightforward. Very few cancers have a single known cause. Most seem to be caused by a complex mix of risk factors, some environmental and some genetic or hereditary. In the case of nasal tumors, exposure to cigarette smoke and living in urban environments appear to be risk factors. In cats, the risk may increase with the exposure to certain viruses. Cats with histories of feline leukemia virus or feline immunodeficiency virus may be predisposed to developing lymphoma, including nasal lymphoma.
What are the clinical signs of nasal tumors?
Most pets with nasal tumors have a nasal discharge (usually pus-like or streaked with blood) from one or both nostrils, noisy breathing (from airflow obstruction), coughing, lethargy, decreased appetite, and weight loss. Some pets, especially cats, will develop facial deformities as the tumor grows. Neurological signs (e.g., seizures, sudden onset of blindness, walking in circles, muscular weakness, and behavior changes) are rare, but may be the only signs seen.
How are nasal tumors diagnosed?
Nasal tumors are typically diagnosed with the use of imaging (X-rays, CT scan, or MRI) of the nasal area. Imaging is especially helpful to determine the size and location of the tumor. To identify the type of tumor, a flush of the nasal cavity may be performed. The cells collected in the fluid are examined under a microscope. If the nasal flush does not provide a diagnostic sample, a biopsy (surgical excision of a piece of the tumor) will be required. The piece (or pieces) of the tumor are then examined under a microscope. This is called histopathology.
How does this cancer typically progress?
Although less than 25% of pets will show signs of spread to the local lymph nodes, routine staging (searching for potential spread to other locations in the body) is highly recommended. This may include a complete blood cell count, chemistry profile to check organ function, urinalysis, repeat X-rays or CT scan of the lungs, and possibly an abdominal ultrasound. Typically, fine needle aspiration (FNA) of the local lymph nodes is recommended. FNA involves taking a small needle with a syringe and suctioning a sample of cells directly from the lymph node and placing them on a slide. A veterinary pathologist then examines the slide under a microscope.
"Treatment is very important as soon as a diagnosis is reached."
Even with a low tendency to spread elsewhere, these tumors have a high tendency to spread locally. Since they spread, are often painful, and can affect the brain (since the nasal cavity is so close to the brain), treatment is very important as soon as a diagnosis is reached. Treatment can control the tumor and relieve the signs. If the nasal tumor is part of a systemic disease (e.g., lymphoma in cats), various signs may develop depending on which organs and parts of the body become affected. Again, timely treatment is helpful to control the tumor and relieve the signs.
What is the treatment for this type of tumor?
The treatment for nasal tumors depends on the specific type of tumor. Radiation therapy is the treatment of choice for dogs with adenocarcinoma. Radiation therapy can provide excellent control of the tumor, as well as relief of the clinical signs. Lymphomas, especially in cats, are also treated with radiation. However, given that lymphoma is usually a systemic disease, tests should be performed to ensure it is not present elsewhere. If it is, chemotherapy is often pursued instead. Regardless, lymphoma is sensitive to both radiation therapy and chemotherapy, and your veterinarian (or veterinary oncologist) will make recommendations on the best course of treatment for your pet.
