Pediatric spay/neuter (Proceedings)

Each year in the United States millions of homeless or unwanted dogs and cats are euthanized in animal shelters and humane societies. While precise numbers are difficult to obtain the estimates range from 3 to 4 million. Many factors have led to the overpopulation of dogs and cats and the solution will be multifaceted. Until safe and effective chemical or immunological sterilization is available spay neuter will be the cornerstone of any program to reduce the overpopulation thereby reducing the numbers of animals euthanized each year.

Pediatric neutering (ovariohysterectomy and castration) is supported by the AVMA and is becoming increasing popular especially in the shelter and high-quality high-volume spay neuter environments. The AVMA position statement says, "Resolved that the AVMA supports the concept of early (8-16 weeks) ovariohysterectomies/gonadectomies in dogs and cats, in an effort to stem the overpopulation problem in these species." "The concept is for the benefit of animal shelter and humane society spay/neuter programs. Individual veterinarians have the right/responsibility to decide on what age they will perform the procedure." Other organizations supporting pediatric neutering include the:

     • Canadian Veterinary Medical Association

     • British Small Animal Veterinary Association

     • European Society of Feline Medicine

     • Feline Advisory Bureau (U.K.)

     • Winn Feline Foundation

The most effective way to ensure that animals adopted from shelters do not reproduce is to spay or neuter them prior to adoption. Voucher programs or prepaid spay neuter programs in which arrangements to have an adopted animal spayed or castrated are made at the time of adoption simply do not work. Nationally compliance rate of these programs is less than 40%. With pre-adoption spay and castration there, obviously, is no compliance issue.

Advantages

There are several advantages to pediatric neutering. In addition to the commonly accepted health benefits associated with ovariohysterectomy and castration, pediatric neutering offers additional advantages. It is an effective tool in dealing with the overpopulation of unwanted dogs and cats. The surgical procedures are easier, faster, and less expensive. The incidence of perioperative complications is low as the surgical procedures and, thus, the anesthetic episodes, are significantly shorter. Anesthetic recovery and healing time is shorter.

Historical Concerns

Historically veterinarians have expressed concerns about pediatric neutering. Their concerns have focused on either potential long-term physiologic effects or anesthetic risk. The adverse physiologic effects mentioned have been obesity, stunted growth, musculoskeletal disorders, perivulvar dermatitis, puppy vaginitis, feline lower urinary tract disease, and urinary incontinence and most fears appear to be unfounded.

Obesity is a multi-factorial problem with a tendency to occur regardless of the age an animal is spayed. A long-term study conducted at Cornell found a decrease in obesity for both male and female dogs that had undergone pediatric ovariohysterectomy.

Initial concerns that pediatric neutering may result in stunted growth have proven to be false. Removal of the hormonal influence actually results in a delayed closure of growth plates. The long bones of animals that undergo pediatric neutering are actually a little longer than those of animals neutered after 6 months of age. There is no clinical significance to the delayed physeal closure.

Some have questioned if early age spay neuter results in an increased incidence of hip dysplasia. Research on this has proven to be equivocal. A study at Texas A&M has shown no increase in hip dysplasia, while a study at Cornell showed a slight increase in incidence. Interestingly, the Cornell study also showed that dogs sterilized at a traditional age were 3 times more likely to be euthanized due to hip dysplasia. This suggests that if early-age gonadectomy increases the incidence of hip dysplasia it may be a less severe form.

Perivulvar dermatitis has been documented in unspayed and spayed animals regardless of the age at which the surgery was performed. This condition is related to obesity and age of neutering appears to have no significant influence on incidence.

There is no difference in the incidence of puppy vaginitis regardless of age of ovariohysterectomy.

Suspicion that pediatric castration would result in decreased diameter of the penile urethra in cats and, therefore, lead to urinary obstruction has proven to be unfounded. The diameter of the penile urethra in the adult male cat does not vary between animals neutered at 7 weeks or 7 months or from intact males.

Studies have shown differing conclusions with respect to estrogen responsive urinary incontinence. The Cornell study revealed a slightly greater risk of urinary incontinence in dogs spayed earlier than 12 weeks of age. The Texas A&M student showed no difference while a study by Arnold et al in 1992 showed a higher incidence of urinary incontinence in dogs spayed after their first estrus cycle.

Anesthetic Management

Anesthetic management in the pediatric patient can be very safe provided attention is paid to a few basic principles and appropriate attention is paid to the unique concerns associated with the pediatric patient. The pediatric patient has an immature liver and kidneys and therefore, less efficient at metabolism and excretion of some drugs. Pediatric patients have lower percentage of body fat, a decreased ability to shiver and a larger surface area to volume ration. Each of these factors makes attention to maintenance of body temperature critical. Pediatric patients are at a greater risk of hypoglycemia. Each of these factors can be easily managed allowing surgical anesthesia with minimal risk.

A pre-operative physical examination should be performed on all patients. Ideally the PCV, total solids, BUN and glucose would be measured. These are usually not performed in the shelter environment.

Body temperature can be maintained by avoiding excessive clipping of hair, using warm surgical scrubs, not using alcohol as part of the surgical scrub and using supplemental heating sources such as water circulating heating pads or Baer Huggers. These measures in conjunction with short surgical time and reversal of anesthetic agents at the completion of surgery minimize hypothermia.

Hypoglycemia can be avoided or minimized by restricting preoperative fasting to 4 hours, avoiding preoperative excitement, and feeding the animal immediately upon anesthetic recovery.

Many anesthetic protocols have been recommended for pediatric surgery. The most recommend protocols use multimodal analgesia and avoid the use of barbiturates and acepromazine. IM injection of a medetomidine, butorphanol, ketamine combination followed by maintenance with oxygen via either face mask or endotracheal tube and supplemented with Isoflourane® if needed is very safe and effective. Following IM injection, a surgical plane of anesthesia is achieved within 5 minutes and will last for up to 30 minutes. The medetomidine can be reversed with atipamezole immediately after surgery and will frequently result in the patient being mobile within 5 to 10 minutes of the conclusion of the surgery. A NSAID like Meloxicam® administered after induction of anesthesia and prior to the start of surgery is generally all that is needed for post-operative analgesia.

Pediatric Surgical Techniques - Feline Castration

Feline pediatric castration is performed essentially the same as castration of the adult cat. For the surgeon just starting to perform pediatric surgery the most difficult aspect is localizing and securing the testicles for incision. The patient is placed in dorsal recumbency with the rear legs pulled forward. The scrotum can be clipped of hair and a surgical scrub performed. The first testicle is grasped between thumb and index finger and secured within the scrotum. A scrotal incision is made over the testicle and the testicle is forced out of the scrotum with digital pressure. Gentle traction is applied to the testicle and spermatic cord while fat and fascia is stripped from the spermatic cord with a gauze sponge. The hemostat tie is used for hemostasis and the testicle is excised. The identical technique is used on the second testicle and the incisions are left open to heal by second intention.

Pediatric Surgical Techniques - Canine Castration

Canine pediatric castration is performed essentially the same as castration of the cat. The surgical incision is made in the scrotum just as in the cat. In most patients only one scrotal incision is needed. The patient is placed in dorsal recumbency. The scrotum is clipped of hair and a surgical scrub performed. The first testicle is grasped between thumb and index finger and secured within the scrotum. A scrotal incision is made over the testicle and the testicle is forced out of the scrotum with digital pressure. Gentle traction is applied to the testicle and spermatic cord while fat and fascia is stripped from the spermatic cord with a gauze sponge. The hemostat tie is used to for hemostasis and the testicle is excised. Generally a second scrotal incision is not necessary. The second testicle can be forced into the surgical wound and the fascia overlying the testicle incised. The excision and hemostasis of the second testicle is performed in a manner identical to the first testicle and the incision is left open to heal by second intention.

Pediatric Surgical Techniques - Feline Ovariohysterectomy

Feline pediatric ovariohysterectomy is performed essentially the same as ovariohysterectomy in the adult cat. The structures are smaller and the exposure can be significantly less. The patient is placed in dorsal recumbency and an incision is made at the midpoint between umbilicus and anterior brim of the pubis on the ventral abdominal midline. The incision can be as small as 1 to 2 cm in length. Any subcutaneous fat (and there usually is none) in the surgical field can be excised exposing the linea alba. An incision is made on in the linea alba. The linea alba is so narrow, that it is nearly impossible to incise precisely on the linea alba. With the abdominal incision this far caudal the urinary bladder can generally be easily visualized. Elevation of the bladder allows direct visualization of the uterine body and / or uterine horns. Deliver one uterine horn through the incision. Apply enough caudal traction to the uterine body to expose the proper ligament and ovary. Clamp the proper ligament with a mosquito hemostat and apply slight upward traction exposing the suspensory ligament. Transect the suspensory ligament with a scissors or scalpel and tear a hole in the broad ligament just caudal to the ovarian vessels. The ovarian vessels can be tied off and transected using the same hemostat technique as in a feline castration.

Gentle caudal traction on the first uterine horn will expose the uterine body and the second uterine horn. The second ovary is exposed and the second ovarian pedicle is tied off and transected in a manner identical to the first.

The broad ligaments are incised to the uterine vessel on both sides allow exposure of the uterine body to the level of the cervix. The standard three-clamp technique is used on the uterine body with the placement of a single ligature on the uterine stump.

Closure consists of simple continuous pattern in the body wall followed by simple interrupted subcuticular sutures to close the skin.

Pediatric Surgical Techniques - Canine Ovariohysterectomy

Canine pediatric ovariohysterectomy is performed similar to ovariohysterectomy in the pediatric cat with only a few differences. The structures are smaller than in the adult dog, the ovaries are more easily exteriorized and it is more difficult to exteriorize the uterine body. For these reasons the abdominal incision in the pediatric dog is slightly caudal to that in the adult dog. The patient is placed in dorsal recumbency and an incision is made just cranial to the midpoint between umbilicus and anterior brim of the pubis on the ventral abdominal midline. Subcutaneous dissection on both sides of the incision exposes the linea alba which is nicked with a scalpel blade. The linea incision is extended with a scissors exposing the abdominal contents. The urinary bladder may be visible and if so it can be elevated allowing direct visualization of the uterine body and / or uterine horns. If the bladder is not visible the uterine horn can be exteriorized with a spay hook. Deliver one uterine horn through the incision. Apply enough caudal traction to the uterine body to expose the proper ligament and ovary. Clamp the proper ligament with a mosquito hemostat and apply slight upward traction exposing the suspensory ligament. Transect the suspensory ligament with a scissors or scalpel and tear a hole in the broad ligament just caudal to the ovarian vessels. A standard 3-clamp technique is used on the ovarian pedicle and the pedicle is transected and ligated. Generally only one ligature is necessary on each pedicle in a pediatric canine spay. Gentle caudal traction on the first uterine horn will expose the uterine body and the second uterine horn. The second ovary is exposed and the second ovarian pedicle is transected and ligated in a manner identical to the first.

The broad ligaments are incised to the uterine vessel on both sides allowing exposure of the uterine body to the level of the cervix. The standard three-clamp technique is used on the uterine body with the placement of a single ligature on the uterine stump.

Closure consists of simple continuous pattern in the body wall followed by interrupted or continuous subcuticular sutures to close the skin.