 What are mast cells?
- Mast cells are normally found in the tissues of the body
- A mast cell tumor is a mass of cancerous mast cells
- They release histamine when stimulated
- Histamine causes signs of allergies such hives
- Histamine increases stomach acid production
- Proteolytic enzymes released by mast cells delay healing of incisions
- Heparin, a blood thinning agent is also found in the mast cells
- This is a photo of a fine needle aspirate biopsy of a mast cell tumor as seen under a microscope; take note of the round mast cells that are filled with purple granules which contain histamine and proteolytic enzymes; the small purple granules surrounding the cells are from mast cells that have ruptured and spilled their granules.
Mast cell tumor locations
- Skin – common location (see photos below of a cat with mulitple mast cell tumors on its head and body)
- Liver
- Spleen
- Gastrointestinal tract
- Blood stream
Signs of a mast cell tumor
- The most common presentation of a mast cell tumor is a lump in the skin; about 10% of the patients will have or will develop more than one mast cell tumor
- The mass may appear as a raised pink lump (see photo below)
- Sometimes the mass may be a less well defined mass
- If the lump is massaged or rubbed it may swell or form hives….called the Darier sign; this is causes by the release of histamine from the mast cells
- The photo right below shows the typical appearance of a mast cell tumor, however other tumors such as benign histiocytomas can look the same.
- Below left is a photo of a dog that has a mast cell tumor located on the ear flap; curative surgery was performed.
Surgery of mast cell tumors of the skin
- Some surgeons prefer to administer Benadryl to the patient prior to surgery to minimize the degranulation effects of the mast cell tumors during surgery, but I have not found this to be needed
- In dogs
- Two centimeters or normal looking skin surrounding the tumor must also be removed with the mass
- A deep layer of tissue below the tumor must also be removed
- The removed tumor is painted with India ink and a pathologist examines the microscopic border of the tissue to ensure that the entire tumor has been removed
- In cats
- Only a small border (0.5 to 1 cm) of normal looking skin surrounding the tumor must be removed with the mass
- These skin tumors in the cat are very different than in the dog and frequently have an excellent prognosis with surgery
Prognosis
- Dogs
- Prognosis of mast cell tumors of the skin is directly related to the grade of the tumor as determined by the biopsy results (histopathology)
- If the tumor has been completely removed with surgery, then recurrence of the tumor should be low
- Grade 1 – benign behavior – excellent cure rate with surgery
- Grade 2 – moderately malignant behavior – recurrence rate is about 20% with aggressive surgery
- Grade 3 – very malignant tumor – only 10% of these patients are alive at 1 year – most of these have spread of tumor
- Some pathologists subclassify grade 2 mast cells as high grade 2 or low grade 2 mast cell tumors; high grade 2 tumors behave like grade 3 tumors and low grade 2 mast cell tumors behave like grade 1 tumors
- Mast cell tumors located on the muzzle and oral cavity tend to have a more malignant behavior
- Mast cell tumors located in the perineal region (anus, scrotum and vulva) may not have as aggressive of behavior as previously believed, however tumor in these locations may be more difficult to remove
- Dogs that have evidence of mast cells also in the internal organs, blood stream or bone marrow have a poor prognosis
- Tumors that are ulcerated may result in a poor prognosis
- Dogs that have signs of gastrointestinal ulcers (vomiting, black stools) generally have a poor prognosis
- Tumors that are large have a poor prognosis
- Tumors that have shown recent rapid growth have a poor prognosis
- Tumors that have recurred after surgical removal may have a poor prognosis
- Mast cell tumors which have not changed for a period of 2 months frequently have a good prognosis
- Dogs living greater than 30 weeks after surgery and not having any recurrence of local or distant tumor are considered cured
- Cats
- Prognosis of mast cell tumors of the skin is usually excellent and surgery is generally curative
- Prognosis of mast cell tumors localized to the spleen is good and many live for an additional one to two years after the spleen is removed
- Prognosis is somewhat guarded if the mast cell tumor is located in the gastrointestinal tract; I treated a cat, named "Meatball", that had intestinal mast cell tumors that were treated twice with surgery and long term prednisone and lived for 4 years from the time of diagnosis
- Sometimes we find cats that have multiple mast cell tumors all over their body and these may have spontaneous resolution of the tumors or may progress with time and result in death
Paraneoplastic syndromes
- Paraneoplastic syndrome is another disease caused by a tumor due to chemicals released by the tumor or a reaction that the tumor causes on other body systems
- Stomach ulcers can develop if a mast cell tumor releases enough histamine into the blood stream
- Signs of stomach ulcers include the following
- Vomiting blood or coffee ground-like material
- Black stools
- Decreased or loss of appetite
- Stretching
- Local bleeding tendencies
- Local swelling around the tumor
- Shock and death due to acute degranulation of the tumor cells
- Poor healing of the tumor
Adjunctive therapy for incomplete excision of mast cell tumors
- Additional surgery can be done to remove more tissue
- This should be the first choice of treatment if the excision is incomplete and additional tissue can be safely removed
- The tissue again is sent to a pathologist to ensure that the entire tumor has been removed
- Drugs
- Prednisone, which is a steroid will help to shrink the tumor size; prednisone does not kill the tumor cells rather decreases the size of the tumor by reducing tumor-associated inflammation
- Vinblastine (chemotherapy) may have some benefit
- Radiation therapy
- Mast cell tumors are very sensitive to radiation therapy
- This therapy can be used if some tumor cells are left behind after surgery and additional surgery is not possible
- Radiation therapy is not a good choice if the tumor has spread to the internal organs
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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 tylenol with codeine, tylenol 3, tylenol 4, morphine, fentanyl patches, 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 with your finger; 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 regurgitant 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 or tylenol/codeine 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. The tylenol/codeine should be discontinued and another type of pain medication tried to help minimize vomiting.
- 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 Serenia 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?
- Pain medication such as tylenol with codeine, butorphanol, Duragesic (fentanyl patch) anti-inflammatories such as Deramaxx, Rimadyl, Previcox, or Etogesic; in some cases a sedative such as acepromazine will augment the effect of pain medication and allow your pet to sleep
- 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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