Tumors of the Mouth in Dogs - Oral Cancer
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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Key Points

Tumors of the oral cavity are best treated when the tumors are small

For many of the tumors aggressive is needed to obtain a cure

In spite of removing substantial sections of the jaw the appearance is still cosmetic

Reconstructive surgery can be done to restore the shape of a jaw bone using bone grafts


Prevalence of oral tumors

  • 6% of all types of cancers in dogs are located in the mouth cavity
  • These are the fourth most common type of cancer

 

Types of tumors

  • Benign - don't spread and potentially can be successfully removed
  • Malignant - grow deeply into the tissues (have roots) and/or spread to the rest of the body very quickly

 

Oral epulis

  • Do not spread to the rest of the body
  • Fibromatous epulis
    • usually a tumor that is located at the margin of the gums
    • generally are smooth, pink and do not have an ulcerated (raw) surface
    • surgical removal is generally curative
  • Ossifying epulis
    • tumor is smooth and nonulcerated
    • can be more difficult to cure by simply cutting the mass off
    • after this type of mass has been removed the bed is treated with cryosurgery (3 cycles of freezing)
    • sometimes a more radical surgery is needed, which involves removal of a part of the underlying bone (partial maxillectomy, partial mandibulectomy)
  • Acanthomatous epulis
    • tumor may have ulcerated or smooth surface
    • these tumors most commonly affect the front part of the lower jaw
    • tumor originates from the ligament (periodontal ligament) that holds the tooth root in the bone
    • tumor is very locally invasive and therefore is considered a type of cancer
    • in order to remove the tumor a portion of the bone also needs to be removed (maxillectomy, mandibulectomy)
    • with surgery these tumors have a 95% chance to be cured
    • if the tumor is very small, radiation can be used
    • Photo right is an x-ray of "Bella's" front jaw - take note of the space between the middle teeth which is caused by the tumor that is spreading the teeth apart;  Bella below has a very good cosmetic appearance following removal of the front portion of the jaw

     

Locally invasive malignant tumors

  • These tumors are locally invasive, that is they have roots of cancer that are deeply seated in the jaw bones
  • These tumors have a lower tendency to spread to the rest of the body
  • Fibrosarcoma, soft tissue sarcoma
    • less than 20% spread rate to lungs
    • must perform a radical surgery to attempt to remove this type of tumor
    • radiation therapy is usually recommended following this type of surgery to try to kill the roots of the tumor that may be left behind
    • chemotherapy may be recommended if the tumor is high grade based on biopsy results
    • median survival is about 7 months with radiation alone
    • survival with surgery and radiation therapy is about 1 to 2 years
    • the primary goal of surgery is palliative...to buy time
  • Squamous cell carcinoma
    • if the tumor is located in the front of the mouth there is a very good prognosis as surgery can be curative
    • if the tumor is located in the back part of the mouth, tongue, or tonsils, the spread rate is very high therefore prognosis is poor
    • photo right is an example of a squamous cell carcinoma on the front of the lower jaw, the excised tumor, and appearance of the patient immediately after surgery
    • photo below is the appearance after the front portion of the mandible has been removed. The dog had excellent function of the jaw and was cured of the disease with surgery alone.

Malignant tumors that tend to metastasize (spread)

  • Melanoma
    • may appear as a black mass, but some do not have the pigment (amelanotic)
    • locally invasive
    • at the time of diagnosis, many have already spread to local lymph nodes or the lungs
    • radical local surgery is needed to remove the tumor
    • if the lymph nodes are large, radiation therapy may be used as they tend to respond well to this treatment
    • chemotherapy may also be recommended
    • size counts with this tumor
      • if the tumor is less than 2 cm in size, the median survival is 511 days
      • if the tumor is greater than 2 cm, the median survival is 164 days
    • the grade of the tumor on biopsy also dictates prognosis
    • the stage, or evidence of spread of tumor to the rest of the body is important
      • stage 1 (tumor isolated the jaw alone) - as a greater than 2 year survival
      • stage 2 (tumor spread to local lymph nodes) and stage 3 (tumor in nodes and lungs) - have a poor prognosis
  • Osteosarcoma
    •  if this type of tumor is located on the upper jaw (maxilla) the prognosis is generally poor with mean survival of about 5 months due to spread of tumor to the lungs and other parts of the body (in this set of cases only surgery was performed);  our oncologist has seen a mean survival of about 1 year with surgery and chemotherapy
    • the photo right is a case of osteosarcoma of the roof of the mouth (hard palate)
    • if this tumor is located on the lower jaw (mandible) the prognosis is much better and surgery can be potentially curative; one report showed a 71% survival rate at 1 year after surgery (this means that nearly 3/4 of the dogs were still alive at 1 year!)

 

Diagnostic tests

  • Complete blood cell count, Chemistry profile, Urinalysis are performed to evaluate the overall health of the patient
  • Chest radiographs (x-rays) are used to help see if the tumor has spread to the lungs
  • Oral radiographs (x-rays) are taken of the tumor site to see how invasive the tumor is in the bone
  • Biopsy of the tumor - a small piece of the tumor is sent for analysis by a pathologist to determine the type of tumor that is present as this will give an idea on the prognosis
  • If any lymph nodes are enlarged, a fine needle biopsy is done to help determine if there is spread to the nodes
  • After surgery has been completed, the entire tissue specimen is sent to the lab to check the margins to ensure that all of the cancer has been removed

Surgery

  • Maxillectomy - removal of the upper jaw
  • Mandibulectomy - removal of the lower jaw
  • In some cases the entire jaw bone is removed and in other cases in which the tumor is smaller, only a portion of the jaw is removed
  • In spite of removing relative large portions of a jaw bone, the cosmetics are still very good
  • Dr. Degner has the capability to rebuild a jaw bone using microvascular surgery and transplantation of a bone graft from the shin bone or other bones.
  • In the photo right (put cursor on image to see removed part), the front part of the upper jaw was removed to treat an acanthomatous epulis; take note of the very good cosmetic appearance of the "Duchess" three years after surgery

                 

 

 

 

 

 

 

 

  • Photos right is a fibrosarcoma which was treated by removing the entire left lower jaw bone (mandible); take note of the good cosmetic appearance after surgery in the photo below.

             

 

Aftercare

  • Feed soft food for about 3 weeks or until your veterinarian indicates that the incisions have healed well
  • No chew toys or raw hides for 3 weeks
  • Limit activity - no rough play until your veterinarian indicates that it is safe to return to normal activity
  • Hot pack the face three times daily 10 minutes each time until the swelling resolves
  • Flush mouth with water or antiseptic such as Nolvadent after eating
  • If malignant tumor was removed chest radiographs should be taken every 3 months
  • If chemotherapy or radiation is recommended, schedule an appointment with an oncologist

VIDEO - ROSTRAL MANDIBULECTOMY - CLICK HERE TO SEE SURGERY - WARNING...DO NOT WATCH IF YOU HAVE A WEAK STOMACH

Frequently Asked Questions After Surgery

When should my dog have the first bowel movement after surgery?

  • Many dogs will not have a bowel movement for the first 4 to 5 days after surgery
  • Reasons that a dog will not have regular bowel movements after surgery include:
    • The dog has been fasted prior to surgery
    • Dogs do not eat well during the hospital stay
    • They frequently do not eat well when they go home
    • They are fed highly digestible food that produces little stool
    • Pain medication that contain narcotics (such as morphine, fentanyl patches, and tramadol) can be constipating
  • If a pet does not have a bowel movement on the 5th day of being home, a stool softener such as metamucil can be fed
    • Dose of metamucil is 1 tsp per 25 Kg mixed in with each meal (canned dog food); feed immediately after mixing, as the metamucil will gel the food and may make it less palatable

My pet had surgery and will not eat.  What can be done?

  • Dogs
    • Most pets will not eat their regular dog food after surgery, especially if it is kibble.
    • Offer a cooked diet having a 1:1 ratio of a protein source and carbohydrate source.  The protein source can be any meat (example: chicken breast, turkey breast, lean hamburger) that is low in fat and should be cooked (drain off all fat after the meat has been cooked).   The carbohydrate can be pasta, potato or white rice.
    • Try canned dog food; to enhance the flavor sprinkle a very small amount of garlic powder or chicken or beef broth (Chicken-in-a- MugTM or Beef-in-a-MugTM products)
    • Try Gerber strained meats for babies such as the chicken, beef, turkey, or veal
    • Try Hill's A/D diet available at most veterinary hospitals
    • Hand feeding: place a small amount of food in the mouth so that your dog gets the flavor
    • Warm the food slightly in a microwave, as the food will be more aromatic; stir the food before feeding and test the temperature on the bottom side of your wrist; it should only be luke warm.
    • Remember that most pets will not eat the first day or two after they get home from surgery
  • Cats
    • Offer smelly foods that contain fish such as tuna or smelly cat foods
    • Try Gerber strained meats for babies such as the chicken, beef, turkey or veal
    • Hand feeding:  with your finger place a small amount of food on the roof of your cat's mouth; use a syringe to get soft food into the mouth
    • Warm the food slightly in a microwave as the food will be more aromatic; remember to stir the food before feeding and test the temperature; it should be only luke-warm
    • Some cats will only eat dry food, try kibble if your cat normally has been fed that food
    • Petting and stroking your cat frequently will help to stimulate appetite
    • Remember that most pets will not eat the first day or two after they get home from surgery
    • Appetite stimulants such as cyproheptadine may be helpful
    • If your cat refuses to eat anything for 7 days a stomach tube or nasogastric tube should be placed to provide nutrition so that a serious liver problem (hepatic lipidosis) does not develop

My pet is vomiting.  What can be done?

  • The first thing for you to discern is whether your pet is vomiting or regurgitating.  Both will result in fluid or food being brought up.  Vomiting always will have heaving or retching of the abdomen prior to expulsion of the vomitus.  Regurgitation is not associated with heaving and the pet usually just opens the mouth and fluid or food will be expelled.  Usually the regurgited material will be clear or brown colored fluid. 
  • Next is to identify the cause of the vomiting or regurgitation.
  • Causes and treatment of vomiting after surgery
    • When some pets return home after a stay in the hospital they may drink excessive amounts of water at one time and then vomit; if this appears to be the case, the water should be limited to frequent smaller amounts.
    • Medications such as antibiotics, narcotics or nonsteroidal anti-inflammatory medication commonly cause vomiting after surgery.  In order to see which medication is causing the problem, the administration of each drug should be separated 2 hours apart.  Usually the pet will vomit or appear nauseated (drooling and sick look) within 1 hour of administration of the medication that they are sensitive to.  The antibiotic in some cases may be changed to a different one, or may be discontinued. 
    • Stomach upset from anesthesia is a potential cause of vomiting and will pass within a couple of days. 
    • An uncommon cause of vomiting after surgery is internal organ failure.  Blood testing will confirm this problem. For this reason vomiting should not be ignored if it persists for more than 24 hours.
    • If your pet had surgery of the bowels or stomach, vomiting is always a concern, as it may indicate that infection of the abdominal cavity, called peritonitis, is present.  Do not ignore this sign.
    • Symptomatic treatment of vomiting involves withholding food for 12 to 24 hours, then introducing small amounts of bland food such as rice and lean cooked hamburger, if your pet does not vomit after that then gradually wean him/her back onto the regular diet after 3 days.  In order to decrease the acidity of the stomach, Pepcid AC 0.5 mg/kg can be given by mouth twice daily for 5 days.  Metoclopramide and Cerenia are good anti-vomiting medications for dogs and cats.  You should always consult a veterinary healthcare professional before administering medication.
  • Causes and treatment of regurgitation after surgery
    • The most common cause of regurgitation is reflux of acid from the stomach into the esophagus while your pet is under anesthesia.  Acidic fluid from the stomach can cause a chemical burn of the esophagus and result in a bad case of heart burn, called esophagitis.  This results in poor motility of the esophagus, therefore water and food will accumulate in this structure.  In most cases, esphagitis is self-eliminating and will resolve within two or three days. 
    • If the esophagitis is severe the esophagus may develop one or more strictures.  A stricture is a narrowing or stenosis of the esophagus and does not allow passage of food down the esophagus, in regurgitation that lasts longer than one week.  This problem should be brought to the attention of your pet's doctor within the first two weeks so that it can be treated by ballooning the stricture (minimally invasive procedure, as it is done with the aide of an endoscope).  If an esophageal stricture is chronic surgery is needed.
    • Symptomatic treatment of regurgitation caused by esophagitis includes feeding bland food, and administering a coating agent (sucralfate) and an acid blocker (omeprazole or other).  Consult a veterinary health care professional if the regurgitation continues for more than a couple of days.

How do I know that my dog is in pain following surgery?

  • Signs of pain include
    • crying
    • biting if you get near the surgical site
    • grimacing (lips are pulled back and the the dog looks anxious)
    • tragic facial expression
    • panting
    • restlessness and unable to sleep; pacing
    • if abdominal surgery was done the pet will not lie down on the incision, or will continually sit up in spite of appearing very tired
    • the worst pain will be for the first 2 to 3 days after surgery

What can I do to control my dog's pain?

  • Narcotic medications that control pain: tramadol, butorphanol, Duragesic (fentanyl patch)
  • Anti-inflammatories used to control pain: Deramaxx, Rimadyl, Previcox, or Etogesic
  • If an orthopedic surgery has been done cold packing the surgical site may be helpful
    • A cold pack may be a pack of frozen peas, crushed ice in a Ziploc bag, or a cold gel pack; place a thin barrier between the skin and the cold pack.  An alternative to a cold pack is to freeze water in a styrofoam cup; after frozen cut the bottom of the styrofoam cup out. Cool the surgical site around the incision by rubbing the exposed ice directly on the skin in a circular pattern.  Cooling the surgical site helps to numb the area.

How do I know that my cat is in pain following surgery?

  • Pain is more difficult to assess in cats versus dogs, as signs can be more subtle and they usually do not vocalize when in pain
  • Signs of pain in a cat include the following:
    • biting if you get near the surgical site
    • growling or deep cry
    • not wanting to eat
    • hiding and not wanting to be near owner (remember that this could also be caused by the cat just being upset about leaving home and coming back)

What can be done for pain at home for my cat?

  • Pain medication such as buprenorphine or a Duragesic (fentanyl) patch
  • Tylenol will kill a cat as they lack abundant glutathione enzyme in the liver
  • Anti-inflammatories can be used, but the dose is much less than dogs

Is it okay for my pet to lick the incision?

  • If a dog licks the incision, the healing process may be delayed.
  • Licking can remove stitches and cause the incision to open
  • Licking can become a severe habit that is difficult to break
  • Licking can cause infection as the mouth has many bacteria
  • Dogs will frequently lick the incision when the owner is not watching such as at night time; if the skin looks red or excoriated the most common cause is from licking.
  • To stop your pet from licking the following can be tried:
    • Elizabethan collar can be placed on the neck; this will not help stop your pet from scratching at the region
    • Cervical collar (bite not collar) is a less awkward device and can be effective at stopping a pet from licking the surgical site
    • A tee shirt can be used to cover an incision on the chest or front part of the abdomen; gather the waist of the shirt up over the dog's back and wrap an elastic band around this part of the shirt.
    • A bandage or sock can be used to cover an incision on a limb; fasten the top of the sock to the dog's limb with tape.
    • Bitter apple can be applied around the incision; many dogs will continue to lick  after application of this topical
    • Bitter Apple and Liquid HeetTM (obtain this from a drugstore...it is used for sore muscles) mixed in a 2:1 ratio can be applied around the skin incision
    • Antipsychotic medication in some cases is needed

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What does it mean?

  • Four years of advanced training in surgery beyond the Doctor of Veterinary Medicine Degree

  • Experience in the development of new surgical treatments

  • Rigorous examination by the American College of Veterinary Surgeons to ensure competency in advanced surgical techniques

  • Assurance that a veterinarian is a surgical specialist

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