Nasal Tumors in Dogs
Nasal tumors make up approximately 1% of all cancers seen in dogs. It is thought that long-nosed breed dogs living in urban environments are at higher risk for the development of nasal tumors. Nasal tumors are seen less commonly in cats and are more frequently seen in older animals.
What are the signs of a nasal tumor?
Symptoms may include the following:
- Nasal discharge
- Bleeding from one or both nostrils
- Facial deformity
- Neurologic signs
Transient improvement in clinical signs is often noted with symptomatic treatments such as antibiotics, antihistamines and steroids, which often delays diagnosis.
Other diseases of the nasal cavity such as fungal infections, foreign bodies and allergies have symptoms similar to nasal tumors.
How are nasal tumors diagnosed?
A CT scan is the ideal way to diagnose and plan treatment of a nasal tumor because it can indicate the presense and extent of the tumor. A tissue biopsy can be planned based on the location of the tumor identified from the CT. A nasal biopsy is easily procured by passing a forceps up the nostril and into the tumor.
Once a nasal tumor is diagnosed, radiographs of the lungs are recommended to evaluate for metastases. Needle aspirates of the local lymph nodes are also recommended to evaluate for spread of disease. Your vet may also recommend an abdominal ultrasound to complete staging.
How are nasal tumors treated?
Dogs and cats with nasal tumors usually present with a relatively advanced stage of the cancer in a critical location near the brain and eyes. Invasion into bone often occurs early and curative surgery is not possible. Chemotherapy alone yields only a 30% response rate and this response is usually short-lived.
Definitive radiation therapy is the treatment of choice in dogs and cats with intranasal cancers. This involves 18-22 treatments administered daily Monday-Friday. Additionally, stereotactic radiosurgery is a procedure that consists of a one-time, high dose of radiation delivered in multiple arcs that target the center of the tumor, minimizing damage to normal tissue around the tumor.
If the tumor is close to or invading important structures such as the eyes or the brain, it may be neccessary to use stereotactic radiation therapy (SRT). The difference between the two is that instead of delivering one large dose, SRT would consist of several (up to three) smaller doses to minimize side effects of the eyes and the brain. Radiation therapy will result in improvement or resolution of clinical signs in the majority of patients.
What are the side effects of treatment?
Side effects are usually minimal but can include the following:
- Change in fur color
- Peeling of the skin
Ulcers and burn-like side effects are temporary and can usually be managed with antibiotics and anti-inflammatory medications. Depending on how close the tumor is to the eyes, the tear production can be compromised, resulting in dry eye.
What is the prognosis for nasal tumors?
Nasal cancer in dogs and cats is not curable. However, patients undergoing radiation therapy can achieve clinical remission with good quality of life. For cancer other than nasal lymphoma, radiation therapy will result in remission times ranging from 9-15 months, with an average of 12 months. Dogs and cats with significant extension into the brain have a poorer prognosis, with average survival times of 4-6 months, even with radiation therapy.
Survival times in patients with nasal lymphoma following radiation are often 2 years or longer, although some patients may develop systemic lymphoma months to years after radiation treatment.