Dr. Lila Miller, D.V.M., ASPCA
Female dogs in heat may attract male dogs from great distances. This is more than just a nuisance. It can result in unwanted pregnancies and present a dangerous situation, especially if several male dogs approach a female at one time. Spaying eliminates this problem.
Spaying eliminates the bloody discharge of female dogs in heat. (Cats typically do not exhibit a bloody discharge)
Spaying eliminates the objectionable behavior exhibited by female cats in heat who yowl, cry as if in pain and may urinate in the house as they seek a male to mate with. (They attract males who will also mark by spraying urine.)
Spaying before the first heat virtually eliminates the development of breast cancer later in life for both dogs and cats. (If the surgery is performed when the animal is older, this benefit will be lost.)
Spaying virtually eliminates the development of pyometras in dogs and cats. Pyometras are infections of the uterus that can also be expensive, life- threatening medical emergencies. (If all ovarian tissue is not removed, a pyometra can still occur in the stump of the uterus that is left behind. This is commonly known as a stump pyometra.)
Spayed animals are not sexually frustrated! Intact animals become sexually frustrated when responsible pet owners do not permit them to mate and satisfy those hormonally driven urges. Without estrogen, these urges are not present and the animals are more likely to focus their attention on their human family rather than on reproduction.
An ovariohysterectomy, or spay, should not be dismissed lightly as a simple surgical procedure. It is major abdominal surgery. Veterinary surgeons will always say that there is no such thing as a “routine” spay, as each procedure is potentially different. The differences range from anatomic differences of the uterus and ovaries, undiagnosed pregnancies and pyometras, to the physiologic differences in each surgical patient that can render anesthesia a challenge. Some veterinarians refuse to spay animals in heat because the blood vessels, ovaries and uterus are enlarged, easily torn and there tends to be more bleeding. The problems associated with spaying animals in heat are encountered more frequently in dogs than cats.
Spays are performed using general anesthesia and strict sterile technique. (Sterile technique consists of prepping the patient properly and placing a sterile drape over the body and wearing sterile gloves and a gown. Some surgeons also wear caps and masks, but many do not) There are many different drugs that can be used to induce and maintain anesthesia. Surgeons typically find 2 or 3 drugs they are most comfortable with and use them either alone or with gas to maintain anesthesia throughout the procedure. After the animal is placed under general anesthesia, she is placed on her back, the abdominal hair is clipped away and the area is prepped with a surgical scrub. (Some veterinarians spay female cats through an incision in the flank, requiring the cat to be placed on her side. This procedure is more commonly taught in veterinary colleges overseas. It will not be described here.)
An incision is made in the abdomen generally from the area of the umbilicus (or navel) back toward the pelvis. The length of the incision will vary depending on the skill of the surgeon and the size and placement of the organs in the body. Organs are not always the size or in the exact place one would expect them to be. The uterus and ovaries form a Y shaped structure, with the 2 ovaries at the top of the two uterine horns, which then converge at the base of the Y to form the uterine body. The surgeon must expose the 2 ovaries at the front (or cranial end) of the incision and the body of the uterus at the back (or caudal end) of the incision. Animals that have undergone a pregnancy tend to have a much more flexible uterus, sometimes enabling the surgeon to expose the ovaries more readily through a smaller incision than in an animal that has never had a litter. Conversely, the uterus also tends to be thicker after pregnancy and thus may still require the use of a longer incision. The quality of the surgery should not be judged solely by the length of the incision. It is simply not a valid measuring stick.
After the ovarian and uterine vessels have been tied off and the ovaries and uterus removed, the abdominal incision must be closed. There are many different ways to close the incision, and the method chosen will depend largely on the patient’s size, condition and temperament, and the surgeon’s skill and choice of suture materials. Some veterinarians may perform a 4-layer closure on an older, fat dog, while others may close with 2 or 3 layers. Pediatric patient’s incisions are frequently closed in 2 layers using subcuticular (under the skin) suture patterns and/or glue so nothing is left exposed for them to play with. In some cases where complications have been encountered, the surgeon may decide to close the incision with wire sutures that remain in place for the life of the animal, and to send the animal home with a protective belly bandage and E collar for the first few days post operatively.
Experienced surgeons can spay a pediatric patient in anywhere from 7-15 minutes, whereas the surgery in an adult can take anywhere from 20 minutes to over an hour in older or fat animals.
The most common complications include bleeding, infection, opening of the abdominal incision (dehiscence), failure to remove the ovaries completely (the animals still go into heat), anesthesia related problems and accidental ligation of the ureters.
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