Pets and People
Surgical sterilization of the female dog, commonly referred to as spaying, is one of the most significant aspects of female dog care an owner can provide.
Spaying involves removal of the uterus and ovaries. It is a major surgery but a commonly performed one, ideally performed while a female dog is still in puppyhood, prior to her first heat cycle. A female dog spayed before her first heat will have a near zero chance of developing mammary cancer. After the first heat, the incidence of tumor development climbs to seven percent and after the second heat the risk is 25% (one in four!). It is easy to see that an early spay can completely prevent what is frequently a difficult and potentially fatal form of cancer.
It is not too late if a dog is already past her second heat. In fact, spaying is important even in female dogs who already have obvious tumors. This is because many mammary tumors are stimulated by estrogens; removing the ovaries, the source of estrogens, will help retard tumor spread. Spaying removes the uterus and both ovaries and is crucial in preventing as well as treating mammary cancer.
In unspayed dogs a life-threatening infection of the uterus that generally occurs in middle-aged to older female dogs in the six weeks following heat is called “pyometra.” The hormone progesterone, which primes the uterus for potential pregnancy, does so by causing an increase of the blood-filled uterine lining and suppressing uterine immune function.
It is thus easy during heat for bacteria in the vagina to ascend to the uterus and cause infection. The uterus with pyometra swells dramatically and is filled with pus, bacteria, dying tissue, and toxins. Without treatment, the dog is expected to die. Despite her serious medical state, she must be spayed quickly if her life is to be saved. Older, unspayed female dogs have an irregular heat cycle. There is no end of cycling comparable to human menopause. If you still decide against spaying, be familiar with the signs of pyometra, which include loss of appetite, lethargy, vomiting, excessive thirst, and usually (but not always) obvious vaginal discharge.
Female dogs come into heat every eight months or so. There is a bloody vaginal discharge and local male dogs are attracted. Often there is an offensive odor. All of this disappears with spaying, not to mention the inconvenience of an unplanned litter of puppies to house, clean, feed and adopt out.
Before the operation It is important that the patient has not been fed in at least eight hours. Anesthetic medications commonly induce nausea and vomiting can be dangerous in a sedated patient (vomit can be inhaled/aspirated leading to pneumonia). A preoperative evaluation is performed; blood work is recommended for older females and may be recommended as a normal preanesthetic consideration.
A medication is given intravenously to induce sleep. This medication is called an induction agent and lasts only long enough to establish the maintenance of anesthesia by the inhalant anesthetic (gas). Once the dog is asleep, a tube is placed in her throat to ensure that a clear airway is maintained throughout the procedure. The tube is hooked up to a machine that delivers a specific concentration of inhalant gas mixed in 100 percent oxygen. A technician is assigned to monitoring this pet so that the concentration of inhalant gas can be changed as needed and patient mucous membrane color, heart rate, respiration and other parameters are followed.
In the surgical prep area, the abdomen is shaved and scrubbed. The bladder is emptied and the patient is moved to a surgical suite, where she is draped with surgical cloths or papers to isolate the area where surgery will take place.
An incision is made on the midline of the abdomen, and the three points where the ovaries and uterus attaches are tied off and cut. The abdomen is checked for bleeding and two or three layers of stitches are placed to close the incision. It is helpful to know that should the skin stitches come out, there are two layers below holding everything closed. Sometimes skin stitches are not placed but if they are, you will need to return in 10 to 14 days to have them removed. The patient is kept in an observation room until she is able to walk.
Most spay patients go home the next day as if nothing had happened, although some will need pain medication for a few days.
Dogs who show a propensity to lick their stitches will need an Elizabethan or "E" collar to restrict access to the stitches. This is not comfortable for the dog but it must be used strictly until the stitches are out and the incision is healed. Activity should be restricted during the week following surgery. Excessive activity can lead to swelling or fluid accumulation under the incision or even worse, a tear in the internal incision line. If a fluid pocket forms, it should resolve on its own after a few weeks. If something has torn inside, obviously the situation is more serious so it is wise to have any incision swelling inspected at the veterinarian's office. Fluid drainage from the incision would also be reason for a recheck.
Spaying while the dog is of a smaller size makes for less trouble with bleeding in surgery and an easier recovery after surgery. Larger dogs are a more difficult surgery and are generally more costly to spay.
Research has shown that there is an increased incidence of some other problems in some breeds when they are spayed young. For some breeds, there is an increased incidence of urinary incontinence associated with spaying before age one year. For larger breeds, the situation becomes more complicated. The problem for large breed female dogs is that some breeds have a higher incidence of joint and bone issues or increased incidence (albeit small increases) in other types of cancers when they are spayed young.
Consult with your veterinarian about these important decisions.
Dr. Lamb is the Veterinarian at the Manchester Animal Hospital.
