Dr. Lila Miller, ASPCA
The surgical altering of animals so that they cannot reproduce (otherwise known as gonadectomy) has been going on for centuries. It seems ironic that despite having spayed and neutered millions of animals, sufficient conclusive research has not been conducted to end the debate about the best age or reproductive stage of life to spay and neuter dogs and cats. Early age spay neuter is still one of the more hotly debated issues in companion animal medicine today. It is fraught with misinformation, misconceptions and high emotions. Hopefully the debate will end as more research shows the procedures to be safe in both the short and long term, and veterinarians will then begin to embrace the concept as readily as they embrace neutering at 6 months of age.
EARLY AGE SPAY-NEUTER
Although the harshest criticism of early age neutering is reserved for surgeries performed on animals as young as 6-8 weeks or 2 pounds, early age spay neuter should be defined as procedures performed on animals less than 6 months of age. Because the term “early” implies that the procedure is being performed prematurely, some veterinarians are proposing that alternative language be used. Some alternatives for early age spay neuter include:
JUVENILE SPAY NEUTER
PEDIATRIC SPAY NEUTER
PREPUBERAL SPAY NEUTER
PREPUBERTAL SPAY NEUTER
PREPUBESCENT SPAY NEUTER
It will be referred to as pediatric spay neuter for the rest of this article.
HISTORY OF SPAYING AND NEUTERING
Many veterinarians are not aware of the different theories that have been advanced regarding the timing of spaying a female cat or dog. Both veterinarians and the general public might be surprised to know that in the early 1900s, veterinarians advocated spaying bitches between 3 and 6 months of age, or even prior to weaning. At one time it was believed that it was beneficial for animals to have a litter before being spayed, while another prevailing school of thought, until fairly recently, was that animals should go through one heat before being spayed. Many veterinary colleges are currently teaching that gonadectomy can be done safely at any age, but see pediatric spay neuter as a tool for population control for shelter animals rather than for the general public. Six months of age is generally considered to be the standard recommendation for spaying and neutering puppies and kittens. It is unclear from the scientific literature how that conclusion was reached. It is now known that spaying an animal before the first heat prevents the development of mammary gland tumors later in life. Since kittens may go into heat at 4 months of age, waiting until 6 months risks accidental pregnancy and loses the protection against mammary gland cancer. It would appear that decisions about when to spay and neuter seem to be based more on the individual practitioner’s comfort level and familiarity with the surgical technique and anesthesia rather than on any scientific or medical evidence of a physiological reason.
On July 18,1993, the American Veterinary Medical Association (AVMA) House of Delegates approved a resolution on early age spay/neuter which stated, Resolved that the AVMA supports the concept of early (8-16 weeks of age) ovariohysterectomies/ gonadectomies in dogs and cats, in an effort to stem the overpopulation problem in these species. Aware of the controversy surrounding this statement they also added that The concept is for the benefit of animal shelter and humane society spay/neuter programs. Individual veterinarians have the right/responsibility to decide at what age they will perform the procedure. Throughout the 1990s groups such as American Animal Hospital Association (AAHA), the American Society for the Prevention of Cruelty to Animals (ASPCA), American Humane Association (AHA), Cat Fanciers Association (CFA), American Kennel Club (AKC), Humane Society of the United States (HSUS) and the California Veterinary Medical Association (CVMA) endorsed pediatric neutering.
Despite these endorsements and the body of evidence that has already been gathered through research and anecdotal information from over 20 years of performing the procedures, the debate still goes on.
CONCERNS ABOUT PEDIATRIC NEUTERING
The following concerns are usually cited about pediatric neutering:
Lack of sufficient scientific data about long-term consequences
Lower urinary tract disease
Secondary sex characteristics
Several of the more common concerns about pediatric neutering will be discussed here.
Lack of studies about the long-term effects
The results of studies of the long-term outcome of gonadectomy performed at an early age or traditional age in cats and dogs were published in JAVMA in the December 1, 2000 and January 15, 2001 issues respectively. The studies were performed at the Texas A&M Veterinary College on 269 dogs and 263 cats from animal shelters. The conclusion for dogs was that “with the exception of infectious diseases, prepubertal gonadectomy may be safely performed in dogs without concern for increased incidence of physical or behavioral problems during at least a 4 year period after gonadectomy.” Shelters that held puppies long-term encountered problems with parvo. Shelters that held puppies short-term did not encounter similar disease problems. The conclusion for cats was that ” prepubertal gonadectomy may be performed safely in cats without concern for increased incidence of physical or behavioral problems for at least a 3-year period after gonadectomy”
Obesity is influenced by a number of factors, but spayed and neutered animals do have a tendency to weigh more than intact animals, regardless of whether the surgery was performed prepubertally or at the conven tional age of six months. Dietary indiscretions and lack of activity are the real culprits in this case.
Many veterinarians believe that pediatric neutering will stunt the growth of animals, but the exact opposite is true. The removal of hormonal influences on the growth plates of the long bones results in delayed closure, resulting in bones that are actually a little longer. However, there is no clinical significance to this difference in size.
Refer to secondary sexual characteristics
The effects of pediatric spaying and neutering on behavior remain largely unknown. Neutering at any age reduces the urge of male animals to spray urine to mark territory, roam and fight with other male animals. There is some early evidence that animals that are gonadectomized at 7 weeks or 7 months of age are more active and excitable, and that male and female cats may be more affectionate than those left intact, but this is a fairly subjective observation that requires more research to substantiate.
Lower urinary tract disease
Pediatric neutering has not been found to contribute to a higher rate of urinary tract obstructions in male cats. Studies have been conducted on male cats to study the incidence of urinary tract obstructions in all populations. It was found that the diameter of the penile urethra did not vary between animals neutered at 7 weeks or 7 months of age or from intact male cats. It was originally thought that castrated cats had a higher incidence of urinary tract blockages, but this is not the case. The diameter of the penis in male dogs castrated at 7 weeks of age is smaller as is the os penis, and preputial development is juvenile in comparison with animals castrated at 7 months of age or left intact, but there has been no clinical significance attached to those differences
Secondary sexual characteristics
The vulva of females is smaller than that of intact bitches, but there is no evidence that there is any clinical significance to this size difference. Perivulvular dermatitis occurs in intact as well as spayed females, and is more largely related to obesity rather than sexual status. Mammary glands and nipples are also smaller. The penis and prepuce of male animals will retain a juvenile appearance, but again, there is no evidence of any clinical significance in animals that are not sexually active. There is a reduction in the male cat’s ability to extrude the penis from the prepuce, but there is no knowledge of any clinical problems associated with this, and it can occur whether the surgery is performed at 7 weeks or 7 months of age.
Urinary incontinence, or the inability to control urination, may be observed in female dogs whether they are spayed or intact, and regardless of the age when spayed. Older, intact female dogs may experience incontinence naturally as a result of the decrease in circulating estrogen, which has an effect on the external urethral sphincter. In spayed dogs, incontinence may be seen soon after the surgery has been performed, years later or not at all. It bears repeating that there has been no indication that it occurs at a higher rate in animals spayed prepubertally.
It is true that some shelters find an increased incidence of infectious disease, (in particular, upper respiratory infections (URI) in cats and parvo in dogs), in animals that are neutered prepubertally, but the stress of anesthesia and surgery affects adult animals as well, not just kittens and puppies. One study showed that surgery and anesthesia have little effect on the dog’s ability to mount a humoral antibody response to distemper vaccination. Many of these shelter animals might have developed URI anyway, because of the presence of these infectious agents in shelters. Good screening of surgical candidates, a good veterinary health care program that includes deworming and good post-operative care can minimize the impact of this problem. Shelters that neuter animals only after they have been selected for adoption and send them home after the surgery to recuperate seem to have fewer problems with URI. It was also noted in a study at Texas A&M’s Veterinary College that an increased incidence of parvo was seen more at shelters that had longer holding periods than the ones with short holding periods. This should not be a problem in the private practice clinical setting.
Many veterinarians find that they already subsidize the cost of adult spays with other procedures. Pediatric spays and neuters are less costly in labor and materials, more procedures can be performed safely in the same amount of time as on adults, and they can be discharged the same day. Adult animals are frequently held overnight or longer, adding to the cost. Veterinarians should find that it costs less to perform pediatric procedures.
SPECIAL POINTERS FOR PEDIATRIC SURGICAL PATIENTS
The following pointers highlight the main considerations when performing a pediatric procedure:
The handling of pediatric patients before surgery should be minimized to prevent excitement before sedation for surgery.The staff should be urged to resist the temptation to play with them. Excited animals will resist being restrained and they become more difficult to sedate.
It may be easier to use intramuscular injections for initial sedation, as less restraint is needed.
Animals should not be fasted for more than 3-4 hours before the procedure to avoid hypoglycemia.
Hypothermia can be a problem for these patients. A small area of hair at the surgical site should be clipped and a warm surgical scrub used. The use of alcohol should be avoided or minimized because of its cooling effects on the skin.
There are many different protocols in the literature for pediatric anesthesia. The most successful protocols are usually already in use by the veterinarian with adjustments for the weight difference. The use of inhalation anesthesia mitigates many of the concerns about biotransformation of anesthetic drugs in the liver and kidneys of pediatric patients.
Good monitoring of the patient for safety is no different from the protocols used for any other patient, ie, observing the heart and respiratory rate, depth of anesthesia, color of the patient’s mucus membranes etc.
A supplemental source of heat should be used to prevent hypothermia. Warm water heating pads covered by a blanket or towel on the surgical table work fine.
Some surgeons recommend that the surgical incision for female puppies should be 2-3 cm caudal to the umbilicus for easier exposure to the uterus. Its location remains the same in kittens as it is for adult cats.
Tissues must be handled gently and close attention paid to hemostasis, but this is true in any surgical procedure. The truth is, in most cases, bleeding in these animals is minimal.
Pediatric animals tend to have a lot of clear abdominal fluid, but this is normal.
The animals should be tattooed in the inguinal region or tattoo ink applied to the incision to identify them as having already been neutered. This is more critical for female animals than males, but it might spare male animals from exploratory surgery if it was assumed the animal had bilaterally retained testicles.
Heating lamps are fine to use to prevent hypothermia. These patients should be monitored closely during recovery, and if there are problems, their temperature and blood glucose should be checked.
A small meal should be offered within an hour after anesthetic recovery to minimize the chance of developing hypoglycemia. If there are signs of hypoglycemia, treat quickly and accordingly.
ADVANTAGES TO PEDIATRIC NEUTERING
One of the main reasons why many veterinarians do not perform pediatric spay neuter is that they are most comfortable performing surgery on animals that are 6 months of age and they believe there are no compelling reasons to change the current protocols in their private practices. However, there are actually many advantages to pediatric neutering.
- Veterinarians who are familiar with the surgery insist that it is much less physiologically stressful on younger patients.
- Animals should be fasted for only an hour or two rather than overnight to prevent hypoglycemia, so owners who forget to fast them overnight can still have the surgery performed the same day.
- Animals are awake and ambulatory usually within an hour of completion of the surgery, so they can be fed a small meal and then sent home the same day.
- The surgery is much faster, so it is less stressful on both the patient and the surgeon.
- The surgery is much cheaper because of the use of fewer materials, and because less staff time is needed for surgery and postoperative monitoring.
- If the procedure is performed when the last vaccination is given at 3 to 4 months of age, the veterinarian does not have to worry about the client forgetting to return, or shopping around and going elsewhere for the surgery. It can be included as part of a puppy care package of vaccinations, deworming and neutering. The delay in neutering pets is often responsible for the production of accidental litters that end up at shelters.
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