- Osteosarcoma is the most common bone tumor in the dog.
- Other bone tumors such as chondrosarcoma and fibrosarcoma can affect the bone
- Over 10,000 new cases are reported each year in the United States.
- Any bone in either the limbs or spine or skull can be affected, with the lower part of the radius bone (bone of the front limb) being the most common location.
- Traditionally, surgical management for canine distal radial osteosarcoma has been amputation of the affected limb.
- Limb-spare surgery can be done for dogs that have cancer of the radius bone
- Reasons to avoid amputation and consider limb-sparing surgery instead
- concurrent degenerative joint disease (i.e. elbow dysplasia, hip dysplasia, cruciate rupture)
- neurologic disease
- size of dog being large - large and giant breeds
- Limb-spare surgery can be done in four different ways:
- Replacement of the radius bone with a bone from a cadaver (deceased dog)
- this technique is associated with a very high risk (about 50%) of chronic severe infection that cannot be cured with antibiotics
- this is the most common way that limb-spare surgery has been done
- this is the easiest way to do a limb-spare surgery
- this is NOT the best way to do a limb-spare surgery due to high infection rates
- Replacement of the radius by growing the bone using an Ilizarov technique
- in this technique the section of radius bone with the offending tumor is removed; a second cut is made near the end of the in the remaining stump of the radius bone (about 1 inch of bone); the small segment of bone is slowly moved at a rate of 1 mm per day down the region where the tumor was removed; as the bone segmented is slowly moved new bone forms, basically growing a new bone.
- this procedure can be very successful
- the main disadvantage to this technique is that it can take 4 to 6 months until the healing process is complete and a second surgery is needed to get the bottom portion of the traveling graft to unite with the wrist bones; during this time the dog must wear a circular external skeletal fixator, which is a set of rings and bars with pins that go through the skin a bones
- Replacement of the radius with a metal rod integrated in a plate construct
- the diseased section of radius is removed
- the implant is secured to the bones with screws
- this technique has shown some promising results
- implant is not commercially available to my knowledge, and is being used in clinical research
- Replacement of the radius by with a segment of the ulna bone (living graft) from the patient
- a segment of the ulna is harvested from the limb in which the tumor has been removed
- the blood supply to the ulnar bone graft is re-established using microsurgery; in some cases the ulna bone can be cut, leaving the blood supply intact, and "rolled" into the bony defect, thereby eliminating the need for microsurgery; a CT scan is usually needed to determine if your pet is a candidate for this technique
- this technique has a very low incidence of infection because the bone graft that is used to repair the limb is kept alive by re-establishing the blood supply to the graft
- the graft will rapidly heal to the bones and will become thicker in response to weight-bearing
- the final outcome generally is very good function of the limb
- this is the technique that I recommend due to the low complication rate
- the disadvantage of this technique is that the surgeon needs to be able to perform microsurgery and the procedure takes longer to perform than when a cadaver bone is used
Criteria for a suitable candidate for vascularized limb-spare surgery
- The bone tumor is affecting the radius bone
- The tumor should be localized to the lower part of the bone
- No more than 1/3 of the bone should be affected
- The tumor should not have gross invasion into the soft tissues
- The patient should not have evidence of macroscopic metastatic disease (spread of cancer seen on chest radiographs)
- The patient should not have evidence of infection at tumor site
- The patient should not have any concurrent disease such as hyperadrenocorticism, which could make the patient hypercoagulable.
Staging and testing prior to surgery
- Complete physical examination
- Complete blood cell count (CBC)
- Serum biochemistry profile
- Three view chest radiographs should be performed to rule out macroscopic pulmonary metastasis
- Radiographs of the affected limb are performed to determine cortical involvement of the radius and the adjacent ulna
- The use of computed tomography and magnetic resonance imaging may also help determine cortical and medullary involvement
- Whole body scintigraphy to check for spread of cancer to rest of body (ideal to do this prior to surgery)
- Tissue samples of the affected bone may be obtained for histopathology
- biopsies tracts should be carefully planned to avoid contaminating the adjacent distal ulna and surrounding soft tissue with cancer cells
- Heart ultrasound should be done to rule out cardiomyopathy as the adriamycin that may be used as a chemotherapeutic agent may cause heart failure if the heart is already in a weakened state
- Above right is an example of osteosarcoma tumor affecting the lower (distal) part of the radius bone in a Great Dane
- The cancerous portion of the radius bone is removed
- A segment of the ulna bone on the same limb is harvested and placed in the defect
- The blood supply to the ulnar bone graft is reconnected using microsurgery (see photo right)
- A cancellous bone graft to help stimulate healing is harvested from the humerus bone (same limb as tumor)
- The cancellous bone graft from the humerus bone is packed into the wrist and around the ends of the ulnar graft
- A long plate and screws are used to hold the bones in place (in photo right the plate is fixed to the paw bones with screws)
- The resected radius bone is submitted for biopsy
- The limb is supported with a splint and bandage for 4 weeks
- Ultrasound doppler is performed during the first three days to make sure that the blood supply to the graft is still adequate
- Bone scintigraphy is performed within 7 days after surgery to ascertain ulnar graft viability
- Graft incorporation at the proximal and distal sites can be monitored via serial radiographs
- Viable grafts may show initial cortical bridging at four weeks, and complete incorporation at eight weeks
- Chemotherapy treatments should be started 2 weeks after surgery or once the skin incision has healed. Generally alternating doses of adriamycin and carboplatinum are administered every other week (3 doses of each drug).
- Chest radiography is performed every 3 months to monitor for metastasic disease.
- Spread of cancer to lungs, bones or other areas on body
- Local recurrence of tumor - 10 to 20%
- Anesthetic death - rare
- Graft resorbtion
- Loosening of screws/implants
- Infection - may be cured with antibiotics
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?
- 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
- 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
- biting if you get near the surgical site
- grimacing (lips are pulled back and the the dog looks anxious)
- tragic facial expression
- 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