Nasal Tumors in Dogs
What Are Nasal Tumors in Dogs?
In dogs, canine cancers can develop in many locations throughout the body–most commonly they are found in the nasal passages.
Cancer occurs when genes within a cell mutate and the cell continues to divide with the abnormal genes. In most cases, nasal tumors have grown significantly large before they are diagnosed. They are unlikely to spread to other parts of the body (metastasize), but they can be very damaging to the nose and face if left untreated.
Most Common Types of Nasal Tumors in Dogs
Common forms of nasal tumors can be divided into the following types:
Adenocarcinomas develop from glands that secrete mucus in the nose and tend not to spread to other parts of the body. However, they can cause a lot of damage to nasal tissue. These are the most common types of nasal tumors, most often seen in medium- to large-sized older dogs (10-12 years) that have long noses.
Sarcomas are tumors occurring in connective tissues within the nasal and surrounding (paranasal) sinuses. Connective tissues are the strong, fibrous tissues found beneath the skin, and include bone, muscle, and cartilage. Sarcomas are named for the area in which they occur:
Chondrosarcomas originate in the nose cartilage and tend to occur in younger dogs, compared to other nasal tumors with an average age of 7 years at the time of diagnosis. Chondrosarcomas tend to occur more often in Labrador Retriever, Golden Retriever, Boxer, and German Shepherd breeds.
Fibrosarcomas arise from the connective tissue around the bones in the nose.
Osteosarcomas are tumors that originate in the bones that make up the nose. It is more common to see osteosarcoma of the bones of the limbs.
Squamous Cell Carcinoma is a cancer of the nasal planum, the hairless tip of a dog’s nose. This cancer is rare in dogs, and can be detected early because it is visible on the nose surface. When these cancers occur, they are most often seen in males and in Labrador Retrievers.
Transmissible Venereal Tumor (TVT) is a tumor that can be spread from dog to dog and tends to be seen on the genitalia of dogs from warmer regions like the southern United States. Occasionally, this tumor will grow on the nose and produce a red mass that tends to crumble off the nose. It is more common in dogs that have not been neutered.
Symptoms of Nasal Tumors in Dogs
Nasal tumors often occur within the nasal passages and may go undetected until they are advanced. Many of the early symptoms of nasal tumors may appear similar to an upper respiratory tract infection or allergies and may be treated with antibiotics, antihistamines, or steroids.
Symptoms may initially respond to such treatments, but as the disease progresses, remission of clinical signs with those treatments is no longer possible. Some signs that may be noted in dogs with nasal tumors include:
Sneezing or reverse sneezing
Bad breath, which occurs if tumors protrude into the mouth
Nasal discharge, often appearing like pus (and may be streaked with blood). Nasal discharge may be noted from one or both nostrils
Noisy breathing and sudden snoring
Swelling around the nose, bulging eyes, or other facial deformities
If nasal tumors spread to the brain, a dog may show neurological signs of disease, such as:
Changes in behavior
Causes of Nasal Tumors in Dogs
Nasal cancers have many causes, including both genetic and environmental factors. Any dog can develop a nasal tumor, but they tend to occur more often in medium-to-large breeds, and in older dogs with long noses.
Dogs living in urban areas are more likely to develop nasal tumors, possibly due to pollutants within the nasal passages. Dogs exposed to cigarette smoke may also be at higher risk to develop nasal tumors.
How Veterinarians Diagnose Nasal Tumors in Dogs
Imaging tests such as x-rays, CT scans, and MRIs are usually required to diagnose nasal tumors. X-rays may be used initially to screen for evidence of a nasal tumor, but more advanced imaging with CT scans and MRIs is needed to determine how much the tumor has advanced (called staging) and to develop a treatment plan. CT scans often provide the best picture to gauge the cancer’s spread.
Understanding what caused the tumor is important as well, which means collecting and examining cells from the tumor.
Fortunately, these kinds of tumors do not usually spread, but when planning treatment, veterinarians must ensure that nasal tumors haven’t metastasized. Lymph nodes will be biopsied to look for evidence of cancerous cells. Bloodwork, chest x-rays, and possibly abdominal ultrasound will also be needed to look for spread of the cancer.
Treatment of Nasal Tumors in Dogs
Once nasal tumors are identified in dogs, radiation therapy is the treatment of choice. Although a cure is unlikely, it can reduce symptoms and improve quality of life. A combination of surgery and radiation therapy may be recommended to improve the response to treatment and increase the chances of a cancer remission.
The type of radiation therapy may be determined on how close the tumor is to the brain and eyes. This is because radiation therapy can damage healthy tissue.
If it appears the tumor invaded a bony structure—the cribriform plate—near the brain, a treatment called stereotactic radiation may be recommended. This method divides the overall radiation into smaller doses.
In some cases of nasal tumors in dogs, an anti-cancer pill called Palladia may also be recommended, in addition to radiation therapy, to help shrink the tumor.
Recovery and Management of Nasal Tumors in Dogs
Nasal tumors in dogs are rarely cured, but with radiation therapy, quality of life can be greatly improved and a clinical response is often noted within 2-3 weeks of treatment. Dogs treated with radiation therapy often have a median survival time of 12-18 months, compared to a median survival time of 2-6 months if left untreated.
In addition to treating the tumor itself, medications to manage the symptoms may also be used. Antibiotics, antihistamines, and/or steroids may help initially with nasal discharge. As the disease progresses, appetite stimulants may be needed to help encourage dogs to eat.
Elliot KM, Mayer MN. Radiation therapy for tumors of the nasal cavity and paranasal sinuses in dogs. Canadian Veterinary Journal. 2009;50(3):309-312.
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