Nasal Tumors in Dogs
Alan R. Klag, DVM, DACVIM
Chief of Internal Medicine
Nasal tumors account for approximately 1% of all tumors in dogs. These cases present to the Internal Medicine Department at VSEC with regularity. The most common tumor type is carcinoma with adenocarcinoma being the most common sub-type of carcinoma. Sarcomas comprise most of the remaining tumors with chondrosarcoma and fibrosarcoma being most common. Nasal lymphoma is uncommon in dogs but does occur. In my experience, nasal lymphoma tends to be isolated to the nose +/- regional nodes, although it can be a component of multicentric disease. Non lymphoid nasal tumors tend to be locally invasive with limited metastatic potential. Most dogs with nasal tumors are older, however, certain tumors, such as chondrosarcoma and lymphoma, can occur in younger adults as well. Large breed dogs and those with a longer nose seem to be predisposed to nasal tumors in general. Primary tumors of the sinuses, especially the frontal sinuses can occur, however, they are far less common than tumors originating in the nasal cavity and it is more common for nasal tumors to spread to the frontal sinuses rather than the other way around.
The most common presenting signs for dogs with nasal tumors include: epistaxis, sneezing and nasal discharge. These signs tend to be chronic and progressive over weeks to months. The signs are typically refractory to antibiotics although some improvement can occur if secondary infection is present. It is important to note that the epistaxis and/or other nasal discharge will most often be unilateral in the case of a nasal tumor. The exception to this rule is if the tumor has invaded the ipsilateral nasal cavity, in which case the signs can progress to become bilateral. Many dogs with nasal tumors that occupy a substantial portion of the nasal lumen will also present with stertorous breathing. Less common signs of a nasal tumor include deformity of the nasal, frontal or periorbital bones and if the tumor has breached the calvarium, seizures and other neurologic signs are possible.
Advanced imaging is necessary to investigate for a nasal tumor. Skull radiographs can be done, however, we no longer advise them as the results are often equivocal with further testing needed. We typically combine a CT scan of the head with endoscopy of the nasal cavity and nasopharynx. The two imaging techniques are complementary; the CT scan will allow for visualization of a tumor and identify the extent, location and any bone involvement. The CT scan will also allow for evaluation of the frontal sinuses and other sinus cavities. What the CT scan will not do is tell us what type of tumor we are dealing with and furthermore, if no tumor is present, the CT will not be very informative regarding inflammatory disease. If a foreign body or dental root abscess with oro-nasal fistula is present, the CT can be helpful in detecting this, however, foreign bodies are not always clearly identifiable on CT. The endoscopy will allow for direct visualization of most nasal tumors and targeted biopsy. It also will allow for biopsy of the nasal mucosa in cases of inflammatory disease where no tumor is found on CT, or further evaluate for and allow removal of a foreign body. Although metastases to the lungs are uncommon for nasal tumors, it is usually advisable to image the chest, especially if the patient is going on to have advanced treatment for the nasal tumor. This can be done with chest radiographs or by imaging the chest with the CT scanner at the same time as the head CT. Adding a thoracic CT to the head CT typically results in less cost than 3 view thoracic radiographs and is more sensitive for detection of metastases. Given the advantages of thoracic CT over chest radiographs (including lower cost for patients already receiving a head CT!) and given that pulmonary metastases are unlikely in these patients, it is typically my preference to do the CT of the chest when the patient is anesthetized, rather than have chest radiographs done prior.
As part of our commitment to our referral community and patients, we are excited to have just commissioned a new state of the art 64 slice Toshiba CT scanner at VSEC, which will be up and running by the time you read this. While our older CT unit did an acceptable job of providing good images, the new machine will allow for much greater resolution and for the scans to be done much more quickly. Where the scans previously took an average of 30 minutes with our older scanner, the same study can now be done in a fraction of that time and with much higher resolution. In addition to decreasing the total anesthesia time for patients, the other advantage of this unit is that it allows for rapid scans under sedation/very brief anesthesia for unstable patients.
Treatment for nasal tumors in dogs can be broken down into lymphoid and non- lymphoid tumors. The treatment of choice for non-lymphoid tumors is radiation therapy, which can be palliative (less aggressive) or definitive (more aggressive). The prognosis will vary for each case depending on tumor type, extent of tumor and type of radiation elected. Our radiation oncologist, Dr. Siobahn Haney, can offer our VSEC clients/patients both forms of radiation on-site at VSEC, as well as the newer Cyber Knife radiation therapy off-site. Chemotherapy has little to no benefit for most non lymphoid nasal tumors. Surgery is rarely if ever recommended, due to the invasiveness of the surgery, unpleasant recovery period and most importantly, fairly rapid recurrence of tumor burden (and therefore clinical signs) post operatively. In the case of lymphoma, both radiation therapy and chemotherapy are very effective treatment options and the best outcomes are typically seen when both are used.
Dr. Alan Klag is a Board-Certified Internal Medicine Specialist at Veterinary Specialty & Emergency Center. The Veterinary Specialty & Emergency Center operates state-of-the-art emergency and specialty veterinary hospitals that are open 24/7/365 in both Levittown PA and Philadelphia PA. For more information about our world-class emergency and specialty care, please visit VSEC on the web at www.VSECVET.com.