The Dog Cancer Survival Guide (110 page)

When you need to look up the definition of a word or phrase, find it listed in
Chapter 5
, which begins on
page 46
.

Sarcomas, cancers that develop from connective tissues, account for the other one-third of nasal tumors. Fibrosarcomas develop from connective tissue, osteosarcomas develop from bone, and chondrosarcomas develop from cartilage. While the lymph tissues in the nasal and sinus cavities can also develop cancer (lymphoma), dogs suffer less often from nasal lymphoma than cats do.

Environmental toxin exposure is a risk factor for developing nasal tumors. Substances like secondhand tobacco-smoke, topical insecticides (flea and tick control medications), and indoor coal and kerosene heaters have been associated with nasal tumors.

The nose and sinuses act as a filter for the lungs, removing these and other pollutants and irritants from the air before they reach the interior of the body. Dogs with long noses likely filter more of these pollutants, which is why they are at a higher risk for nasal cancer.

There is also a link between elevated levels of the enzyme called COX-2, which is involved with inflammation, and dogs with carcinomas. It’s possible that inflammation and excess COX-2 expression plays a role in the development of nasal tumors.

Certain breeds are at a higher risk for developing nasal tumors, all having long noses: Airedale Terriers, Basset Hounds, Collies, German Shepherds, German Short-Haired Pointers, Keeshounds and Old English Sheepdogs.

The first sign of a nasal tumor is nasal discharge; unfortunately, a runny nose is not always a red flag for owners, so, the average length of time between first noticing symptoms and getting a diagnosis is three months.

Nasal discharge from one or both nostrils (nares) can be clear, yellow, green, thick or runny. There may be blood in the discharge or your dog could even have a chronic bloody nose (called epistaxis). Some dogs will sneeze a lot. The first diagnosis is often a nasal or sinus infection, and antibiotics may be given. This often improves or even clears up the symptoms at first, but they usually return after the medications are stopped.

Eventually the tumor will fill up the airway and obstruct breathing. As this happens, dogs may breathe noisily or have difficulty breathing (some owners notice this most when their dogs are sleeping). The muzzle may become visibly deformed, and the eyes may bulge out of the skull as they are displaced by the tumor.

A nasal tumor can sometimes affect the temporomandibular joint (TMJ), which is the joint that attaches the jawbone to the rest of the skull. When this happens, your dog can find it painful to open her mouth or chew her food.

In the rare cases when the tumor invades the bone and reaches the brain, there can be seizures or behavioral changes: running around in circles, barking for no reason or other odd behaviors.

Nasal tumors are diagnosed through imaging tests and a biopsy. The first step is to get blood work and a urinalysis, so you can have an overall snapshot of the baseline health of your dog.

“Cry if you need to; but then sit down with the book and a notebook. Write down what supplements sound right to you. Find them on the Internet. Do some research. Consult Dr. D’s blog. Act as if you’re in grad school and really get educated and be proactive. The vets here in North Dakota are not very receptive, and from what I hear, that’s not uncommon. If you don’t have vet support; keep going.”

-Kris Kitko, Bismarck, North Dakota

If your dog is suffering epistaxis (a bloody nose), the cause could be a tumor, and it could also be high blood pressure or blood clotting abnormalities. Make sure her blood pressure gets checked, and that the blood test called a coagulation panel is run to rule out other issues. High blood pressure and excessive bleeding tendencies can also cause problems during nasal tumor biopsy and treatment, so it’s important to have this information in any case.

Imaging tests should be performed to measure the extent and severity of the tumor and to see if it has invaded the bone (many have). While it may seem logical to perform the less invasive and less expensive X-ray screening, it is not sensitive enough to pick up most of what is happening inside the skull, and does not help to diagnose nasal tumors. Good skull X-rays require heavy sedation or anesthesia, too, and do not provide enough information. I recommend saving money and time by skipping the X-ray and getting a CT (computed tomography) scan, instead. It provides much more detail and it is also a requirement for radiation therapy, the standard treatment for nasal tumors.

A CT scan helps the vet know where to look for tumors during a rhinoscopy, or nasal biopsy, also. During a rhinoscopy, a fiber-optic scope is passed up through the nostrils into the nasal cavity to visually inspect the passages for tumors, clumps of fungus (called fungal plaques) and other possible causes of nasal symptoms. Suspicious masses should be sampled this way – through the nose – rather than through the outer surface of the skin, so that cancer cells are not pulled into otherwise normal tissues. Multiple samples must be taken, both for biopsy and fungal cultures.

A recent study shows that a nasal hydropulsion technique, which collects pieces of nasal tumors for biopsy by pushing a large volume of water through the nasal cavity, can literally dislodge and “flush out” nasal tumors in 90% of cases. While this technique does not completely remove the entire tumor, especially a tumor that has invaded the deeper tissues and bones, it can dislodge large enough pieces of tumor to use for biopsy samples. It also can relieve some of the obstruction in the nasal and sinus cavities, making it easier for the dog to breathe for the time being. This technique is worth considering as a biopsy collection strategy because of its debulking and palliative effects (simple saline flushes do not provide large enough biopsy samples to have the same effect). This procedure is typically done under anesthesia.

Rhinoscopy, biopsy and CT scans all require general anesthesia, so they are best done together. The CT scan will be administered first, because rhinoscopy and biopsy can cause bleeding that will show up on the scan and could be misinterpreted as a tumor.

Metastasis at the time of diagnosis is uncommon, but it does happen, and 40% of all dogs with nasal tumors will experience metastasis as the disease progresses. For this reason, and because treatment strategies may alter, depending upon the extent of the metastasis, I recommend staging the cancer – finding out where it is in the body – before starting treatment.

The most common sites of spread are the regional lymph nodes and the lungs. About 10% of dogs have lymph node metastasis at diagnosis, so I typically aspirate the regional lymph nodes under the same anesthesia as the head CT scan, rhinoscopy and biopsy. Aspirate every accessible lymph node, even those of normal size. Three-view thoracic X-rays or a chest CT can show metastasis to the lungs.