Download Oral Cancer (Mouth Tumors) in Cats and Dogs

Oral Cancer (Mouth Tumors
) in Cats and Dogs
로얄벳 동물병원(월계점)
원장 김 희 용
Oral tumors
•
The oral cavity (mouth) is a common site for a variety of tumors, both be
nign (noncancerous) and malignant (cancerous).
The most frequent benign oral tumors are epulides, firm masses involvin
g the gingival tissue (gums). In dogs, the most
common malignant oral tumors are (in decreasing order): oral melanoma,
oral squamous cell carcinoma, and oral
fibrosarcoma. Less common malignant oral tumors in dogs include osteo
sarcoma, chondrosarcoma, anaplastic sarcoma,
intraosseous carcinoma, myxosarcoma, hemangiosarcoma, lymphoma, ma
st cell tumor, and multilobular tumor of bone.
In cats, squamous cell carcinoma (SCC) is the most common oral cancer,
followed by oral fibrosarcoma. To learn about
diagnosis and treatment options specific to feline oral SCC, please click h
ere.
• How common are oral tumors in cats and dogs?
Oral cancer accounts for approximately 6% of all cancers in dogs
and is the fourth most common cancer overall. In cats, it
accounts for 3% of all cancers. Oropharyngeal (oral cavity and ph
arynx) cancer is 2.6 times more common in dogs
compared to cats, and male dogs have a 2.4 fold greater risk of d
eveloping oral cancer compared to female dogs. Dogs
with heavily pigmented oral mucosa, such as chow chows, are at i
ncreased risk of developing oral melanoma. Squamous
cell carcinoma and fibrosarcoma are more commonly seen in larg
e-breed dogs. The median age for developing oral
melanoma is 11-12 years, 8-10 years for squamous cell carcinoma
and 7-9 years for fibrosarcoma.
• What are the symptoms of oral tumors in cats an
d dogs?
Most cats and dogs with oral cancer have a mass in
the mouth noticed by the owner but tumors are rare
ly seen by the
owners in the pharynx. Pets with oral tumors have sy
mptoms of increased salivation (drooling), facial swel
ling, mouth
bleeding, weight loss, foul breath, oral discharge, diff
iculty swallowing, or pain when opening the mouth.
Loose teeth could
be indicative of bone destruction due to the tumor.
How is the diagnosis of oral tum
ors made?
•
A thorough diagnostic evaluation of oral tumors is critical due to the variety of different tumors that could be
present.
Sedation or anesthesia is often required in order to examine the pet's mouth, especially if the suspected tum
ors are
located in the back of the mouth or on the tongue. If the tumor is suspected to be malignant, chest X-ray ca
n be done prior
to biopsy to check for metastasis (spread) to the lungs. Bone destruction is not typically seen on X-rays of th
e mouth until
>40% of the bone is destroyed so what appears to be a normal X-ray cannot exclude the tumor's bone invasi
on. Advanced
imaging such as CT (computed tomography) or MRI (magnetic resonance imaging) can be valuable tools in st
aging the
disease (determining how advanced it is), especially for evaluating bone invasion and tumor's potential extens
ion into the
nasal cavity, pharynx or the eye. The use of CT may eliminate the need for regular X-rays but CT/MRI imaging
is more
expensive.
Regional lymph nodes should be carefully assessed for any abnormalities, although lymph node size is not an
accurate
predictor of metastasis. In a study of 100 dogs, 40% showed normal sized lymph nodes despite being positiv
e for cancer
cells, and 49% of dogs who showed lymph node enlargement did not actually have lymph node metastasis. L
ymph node
aspirates (isolation of cells for microscopic analysis to check for the presence of any cancer cells) are, therefor
e,
recommended for pets with oral cancers.
The final diagnostic step, which is done under anesthesia, is a large incisional biopsy. Biopsy is preferred over
cytology to
definitively differentiate between benign (noncancerous) and malignant (cancerous) tumors and to determine
the exact
type of the tumor present. This is important in order to plan treatment that will best maximize the pet's respo
nse and
survival. For small lesions (e.g. epulides, papillomas, or small labial mucosal melanoma), excisional biopsy (sur
•
Does cancer cause pain in cats and dogs?
Pain is common in pets with cancer, with some tumors causing more pain than others. I
n addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as s
urgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery
from the illness, treatment or
injury. It is, therefore, essential that veterinary teams taking care of pets with cancer sho
uld also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way
to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates
pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the
pet's maximum comfort.
To learn more about how to recognize pain in pets with cancer and what cancer pain m
anagement options are available for
your pet, please visit the Cancer Pain Management section.
•
How important is nutrition for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets wit
h cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered m
etabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically
interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer tr
eatment (for example,
some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth infla
mmation).
Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, impr
ove survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decreas
e the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pet
s with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient
. To learn more, please
visit the Cancer Nutrition section.
• What are the treatment options and prog
nosis for oral cancer in cats and dogs?
To learn about treatment options and prog
nosis for specific subtypes of oral tumors, p
lease click on the appropriate
section below:
Oral
Oral
Oral
Oral
Oral
melanoma
squamous cell carcinoma (dogs)
squamous cell carcinoma (cats)
fibrosarcoma
epulides
•
Where do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your
pet's cancer condition or to provide you with a second opinion, please visit the "Locate a veterinary oncologist" section.
Additional online resources
Tumors of the mouth in dogs - Oral cancer by Vet Surgery Central
•
Finding and treating oral melanoma, squamous cell carcinoma, and fibrosarcoma in dogs by Dr. Coyle and Dr.
Garrett, DACVIM (Oncology)
•
Oral tumors by American Veterinary Dental Society.
•
Canine non-melanoma oral tumors by Dr. Betsy Hershey, DVM, DACVIM (Oncology)
•
Sources:
Finding and treating oral melanoma, squamous cell carcinoma and fibrosarcoma in dogs by Virginia J. Coyle, DVM,
Laura D. Garrett, DVM, DACVIM (Oncology)
•
Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
•
Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998
Fibrosarcoma
Melanoma, squamous cell carcinoma