Nasal Tumors in Pets
The most commonly reported symptom of a nasal tumor is nasal discharge. This discharge is often bloody in nature. Other symptoms include sneezing, reverse sneezing, swellings on the face, and exophthalmia (the globe of the eye being pushed out of the orbit). Nasal tumors tend to occur in middle-aged to older animals. Often the discharge is only from one nostril in the beginning. Other causes of one-sided nasal discharge include trauma and foreign bodies. Infectious causes of nasal discharge generally cause bilateral (both sides) of the nose to have discharge.
Because of the destructive nature of these tumors, most animals improve initially when placed on antibiotics. This is because the tissue is more susceptible to infections and the antibiotic helps with the infection and things seem to improve. It is fairly common for us to see pets that have been treated multiple times with multiple antibiotics and often antihistamines as well. With more advanced imaging techniques, we are starting to diagnose these pets sooner than we previously did. CT scans and rhinoscopy are the most common tools used to diagnose nasal tumors. Because of the very vascular nature of the nasal cavity, it sometimes can be difficult to obtain a definitive diagnosis. Often results that are called inflammatory are obtained. In these cases, when signs and symptoms persist, further work up and repeat biopsies may be required.
The most common nasal tumor in dogs is carcinoma. Sarcomas are the next most common tumor in the nose. These tumors can occur anywhere within the nasal passage including the sinuses. While these tumors are malignant and can spread to other parts of the body, the local disease within the nose is the most common problem. The most common nasal tumor in cats is lymphoma. All of these tumors can all be quite destructive to the normal tissues and the surrounding bone. Because of the proximity of the brain to the nasal cavity, neurologic signs are sometimes seen. Only a small piece of bone called the cribiform plate separates the nasal cavity from the brain. It is rather easy for a nasal tumor to destroy this bone and invade into the brain. When this occurs, the prognosis is worse.
For most tumors, surgery is considered the treatment of choice when possible. For nasal tumors however, surgery has been shown to be a negative prognostic indicator (i.e. dogs did worse when they had surgery compared to no treatment at all). Therefore, radiation has been the treatment choice for dogs and cats and people for many years. Historically, conventionally fractionated radiation therapy, multiple treatments with smaller doses of radiation, has been used for nasal tumors. Treatment consisted of 18 treatments over 3 ½ weeks, after which dogs and cats would have quite severe side effects including hair loss and blister like lesions on the face and within the mouth. With stereotactic radiosurgery, nasal tumors can be treated in only 1 to 3 treatments and side effects are kept to a minimum. Some hair loss on the face is possible and depending on the location of the tumor, dry eye and eventual cataract formation may occur. While cataracts can make your friend blind, they don’t tend to occur for more than one to one and a half years after the treatment and thus, are a sort of blessing in disguise.
With conventionally fractionated radiation therapy, survival times for dogs with nasal tumors was often listed as 10 to 14 months. While data for stereotactic radiosurgery is still immature, we feel it is likely that we are doing at least as well. Because the treatment is delivered so much faster and without all the side effects though, we are clearly in a much better place with stereotactic radiosurgery.
Both carcinomas in dogs and nasal lymphomas in cats seem to be very responsive to stereotactic radiotherapy. It is not unusual for us to see significant improvements in breathing within the first few days to weeks following treatment. Sarcomas however tend to respond much slower. That is not to say that they will not respond, only that it may take many months.
An NSAID (non-steroidal anti-inflammatory drug) called Piroxicam is often prescribed to dogs with carcinomas. While this medication has a narrow safety margin, we find with judicious use it can often slow the progression of these tumors. We do recommend regular bloodwork and checking the pet’s body weight any time an animal is receiving this medication. While this drug won’t stop the tumor, it may assist in our fight against it. Your veterinarian can help with this medication or you can continue to come to Arizona Veterinary Oncology.
Palladia is a newer chemotherapy licensed for use in dogs that likely has a beneficial effect in dogs with nasal tumors that are treated with radiation. This chemotherapy is given at home, usually every other day, for a minimum of 4-6 months following the radiation treatments. It is typically well tolerated but we do recommend monthly bloodwork and checks of the body weight to make sure it is being tolerated well. Some early data that is being submitted for publication looks like the addition of this drug to conventionally fractionated radiation (CFRT) my double the survival times. We hope that SRS and this medication will do even better than that!!
Nasal tumors in pets are more treatable than ever. Talk to your veterinarian today and see if this treatment is right for your friend.