Pediatric spay or neuter neutering (Proceedings)

Adapted from an article originally published in Veterinary Medicine, February 2011.

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 Humane Society of the United States estimates that between 3 and 4 million dogs and cats are euthanized each year (HSUS 2006). 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 relinquished and euthanized each year.

Ovariohysterectomy and castration of pediatric dogs and cats (between 8 and 16 weeks of age) 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 (AVMA 1994)." "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 (CVMA 2006)

     • British Small Animal Veterinary Association (Association 2006)

     • American Animal Hospital Association (AAHA 2010)

The most effective way to ensure that animals adopted from shelters do not reproduce is to spay or neuter them prior to adoption. In fact, the ASV Guidelines for Standards of Care in Animal Shelters states that "animal shelters should require that cats and dogs who are adopted into homes be spayed or neutered (Newbury S 2010)." 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% (Manning AM 1992; AVMA 1997; Petsmart Charities 2010). With pre-adoption spay and castration there, obviously, is no compliance issue. In the shelter environment the authors recommend spay or neuter prior to adoption and as young as 6 weeks of age. In a practice environment for owned animals the recommendation is to establish one more appointment at the end of the puppy/kitten vaccination series. In this manner puppies and kittens are spayed or neutered prior to 5 months of age, before sexual maturity.

Advantages:

There are several advantages to pediatric neutering. In addition to the commonly accepted health benefits associated with ovariohysterectomy and castration, such as reduction in incidence of mammary neoplasia and reduction in behavioral problems, 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. With shorter surgery times and shorter anesthetic episode the incidence of perioperative complications is low (Howe LM 1997). Anesthetic recovery and healing time is shorter (Faggell AM 1994; Howe LM 1997).

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 (Spain C. Victor 2004).

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 (Salmeri Katharine R 1991). 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 does not appear to be any clinical significance to the delayed physeal closure (Salmeri Katharine R 1991).

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(Howe Lisa M 2001), while a study at Cornell showed a slight increase in incidence (Spain C. Victor 2004). 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 (Spain C. Victor 2004).

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 a recessed vulva and made worse by obesity. Age of neutering appears to have no significant influence on the incidence (Salmeri Katharine R 1991). There is no difference in the incidence of puppy vaginitis regardless of age of ovariohysterectomy (Spain C. Victor 2004).

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 (Stubbs WP 1993; Herron MA 1996; Root MV 1996).

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 (Spain C. Victor 2004). The Texas A&M student showed no difference (Howe Lisa M 2001) while a study by Arnold et al in 1992 showed a higher incidence of urinary incontinence in dogs spayed after their first estrus cycle (Arnold S 1992).

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. Given that metabolic development is largely complete by six weeks of age, the same anesthetic protocols that are used in adults can be safely administered (Howe LM 1997; Looney AL 2008). 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, also, at a greater risk of hypoglycemia. Each of these factors can be easily managed allowing surgical anesthesia with minimal risk (Howe LM 1997).

A pre-operative physical examination should be performed on all patients (Looney AL 2008). Ideally the PCV, total solids, BUN and glucose would be measured, however, these are usually not performed in the shelter environment.

According to the Association of Shelter Veterinarians guidelines for spay neuter programs "warmth is best preserved by reducing contact with cold surfaces, limiting body cavity exposure, and providing carefully protected contact with circulating warm water or heated containers, such as carefully monitored water bottles or rice bags. Forced hot air or convective warming can also be an effective means of maintaining body temperature perioperatively (Looney AL 2008)." These measures in conjunction with short surgical time and reversal of anesthetic agents at the completion of surgery minimize hypothermia (Root Kustritz Margaret V 1991).Hypoglycemia can be avoided or minimized by restricting preoperative fasting to 2 to 4 hours, avoiding preoperative excitement, and feeding the animal immediately upon anesthetic recovery (Root Kustritz Margaret V 1991; Howe LM 1999).

Many anesthetic protocols have been recommended for pediatric surgery. The most recommend protocols use multimodal analgesia and avoid the use of barbiturates (Cistola AM 2003). IM injection of a dexmedetomidine, butorphanol, ketamine HCl combination followed by maintenance with oxygen via either facemask or endotracheal tube and supplemented with Isoflurane®, 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 dexmedetomidine 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. The authors recommend an NSAID like meloxicam administered after induction of anesthesia and prior to the start of surgery for post-operative analgesia(Griffin B 2009).

Surgical Procedures

Videos of surgical procedures will be demonstrated.

Conclusions

Recognizing the shorter anesthetic and surgical times and lower complications rates for younger patients, many practitioners have begun performing spays and neuters at an earlier age in privately owned pets as well. Historically, practitioners have routinely seen kittens and puppies for a series of vaccinations and wellness visits between 6 and 16 weeks of age, and then advised owners to return a few months later for neutering. This gap in care may contribute to many pets being spayed or neutered following puberty and the birth of many unintentional litters. By spaying and neutering owned pets at 4-5 months of age following standard vaccinations, practitioners can allow time for them to develop immunity through vaccination while ensuring they are neutered prior to sexual maturity. And, because there is no gap in veterinary care between the vaccine series and the surgical appointment, owner compliance may be improved since the owner establishes a routine of veterinary appointments for their pet during the wellness visits (Griffin 2009). By performing spay-neuter surgery at this age, veterinarians are also able to ensure numerous health benefits for their patients, including dramatic reduction in the risk of mammary tumors and elimination of highly objectionable behavior including scent marking, spraying, fighting and roaming. Additional benefits include avoidance of the stresses and costs associated with spaying while in heat, pregnant or with pyometra. And, spaying and neutering young puppies and kittens is technically easier for the surgeon and more cost effective than neutering them once they are mature.

References

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