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Early-Age Spay/Neuter

By Paula Kislak, DVM





Why Spay/Neuter
Is Crucial

Early-Age Spay/Neuter

Feral Cats in Israel



Cat & Dog Overpopulation

Campaign in the North: Spaying & Neutering Before Adoption


Studies show that gonadectomy (removal of the ovaries or testicles in spay or neuter surgery) in puppies and kittens can be safely performed before puberty without medical or behavioral concerns.


Gonadectomy, one of the most ancient surgical procedures performed on domestic animals, dates from at least 284 B.C. Until the end of the last century, little scientific inquiry was made into the optimal age for this procedure, and postpubertal gonadectomy (performing surgery at or after the age of 6 months) remained the norm.1 In 1974, however, the Southern Oregon Humane Society recognized that many animals in their shelter were the offspring of puppies and kittens adopted from them in the previous six months. Subsequently, they began performing early-age sterilization on kittens and puppies as young as 6 weeks old.


Armed with growing information about the benefits of this surgery, in 1975 the Humane Society of the United States issued a policy stating "No animal should be adopted from any shelter without being spayed or castrated." Many shelters subsequently adopted an early-age sterilization policy, and many, including all shelters in California, are now mandated by law to do so prior to adoption. In 1993, the American Veterinary Medical Association approved a resolution supporting early-age sterilization surgery.


The push to sterilize puppies and kittens at an early age immediately stirred dissent within the veterinary community. To address these concerns, numerous studies have evaluated the safety of the surgery. Anecdotal results from the Southern Oregon Humane Society were published in 1985, and they indicated approximately the same incidence of physical and behavioral complications for both the prepubertal and postpubertal gonadectomized animals. Building on this, Leo Lieberman, DVM, studied early-age sterilization programs at three shelters. Over a two-year period at the Florida SPCA, 1,600 surgeries were performed; 8,000 were performed over a seven-year period at the Southern Oregon Humane Society, and more than 90,000 were performed over an eight-year period at the Vancouver SPCA. Dr. Lieberman found no significantly increased complication rate.2


A well-designed study was done at the University of Florida in 1991 on male and female canine littermates separated and surgically sterilized at 7 weeks and 7 months of age. When the parameters were measured at maturity, no clinically significant differences were found between the groups.3 In another study, seven litters of kittens were divided into three groups sterilized at 7 weeks, 7 months and 12 months. The results, again, displayed no significant differences among the three groups.4 Two articles were published in 1991 that detailed surgical and anesthetic considerations for 96 young kittens. They both concluded “there were no important anesthetic complications or complications during or after surgery.”5,6





And yet, some veterinarians remained skeptical about potential long-term effects of early-age sterilization. One study published in the January 15, 2001, edition of the Journal of the American Veterinary Medical Association addresses the long-term results and complications of gonadectomy performed at an early age versus the traditional age in dogs. The research studied 269 dogs from animal shelters. The results showed prepubertal gonadectomy did not result in an increased incident of behavioral problems or problems associated with any body system, compared with traditional-age gonadectomy, during a median follow-up period of 48 months. The article concludes that early-age sterilization surgery can be safely performed in dogs without concern for increased incidence of physical or behavioral problems.7


Two companion articles published in the Journal of the AVMA in 2004 studied 1,842 dogs and 1,600 cats to evaluate early-age gonadectomy.8,9 They conclude that the benefits outweighed the risks. Both studies maintain that shelters and clients can safely be advised to sterilize their animals prior to the traditional 6 to 8 months of age, with the recommendation that female dogs be at least 3 months of age.


John Hamil, DVM, of Laguna Beach, California, has been a strong advocate of early-age surgery, and he states that "The surgery is faster and technically much easier than it is in older patients. The recovery of young patients from anesthesia is remarkably rapid and complete."10,11 Private practitioners should consider adopting an early-age sterilization policy with their kitten and puppy packages at the end of the vaccination series and prior to puberty.


This places veterinarians in a leadership role to help end the staggering pet overpopulation problem by preventing unexpected pregnancies. Additionally, veterinarians are further fulfilling their responsibilities to their patients by ensuring a dramatic reduction in the incidence of mammary cancer and prostate disease later in life, which is a well-documented benefit of early sterilization. The surgery also is effective in reducing aggression, spraying, roaming and other behaviors often associated with late-sterilized animals and frequently resulting in abandonment and death.


For shelters, sterilization before adoption allows them to release animals without the burdensome follow-up on compliance and other tasks associated with deposits and refunds. In fact, as shelters have begun performing early-age sterilization, they've found the number of cats and dogs turned into the shelter has declined dramatically. Rescue groups and feral cat caregivers can also use this strategy to diminish the potential for careless, avaricious, and irresponsible breeding which results in the wholesale slaughter of over 5 million dogs and cats each year.


Many state veterinary medical associations now endorse and thereby validate the safety, efficacy, and benefits of early-age sterilization. These include the states of California, Massachusetts, Nevada, Oregon, Rhode Island, and Wisconsin. The American Animal Hospital Association, the American Veterinary Medical Association, and the Association of Veterinarians for Animal Rights endorse it, as well as numerous humane organizations, including the Humane Society of the United States and the American Humane Association. In doing so, they provide us with the opportunity and encouragement to use early-age sterilization for improving our patients’ quality of life, as well as addressing the companion animal crisis that affects our communities on many levels.







1 JA Hamil, "Early-age gonadectomy, practitioner participation needed," Pulse, Southern California Veterinary Medical Association, July 1995.

2 LL Leiberman, "A Case for neutering pups and kittens at two months of age," JAVMA 1987; 191: No. 5,518-521.

3 KR Salmeri, PN Olson, and MS Bloomberg, "Elective gonadectomy in dogs: A Review," JAVMA 1991; 198; 1183-1192.

4 MS Bloomberg, WP Stuffs, DF Senior, TJ Lane, "Developmental and behavioral effects of prepubertal gonadectomy," JAVMA February 1991.

5 AM Fagella and MG Aronsohn, "Anesthesia techniques for neutering six-to-fourteen-week-old kittens," JAVMA January 1, 1993; 202: No. 1: 56-62.

6 MG Aronsohn and AM Faggella, "Surgical techniques for neutering six-to-fourteen-week-old kittens," JAVMA January 1, 1993;202:No. 1:53-55.

7 LM Howe, MR Slater, HW Boothe, HP Hobson, JL Holcom, and AC Spann, "Long-term outcome of gonadectomy performed at an early age or traditional age in dogs," JAVMA January 15, 2001; 218: No. 2:217-220.

8 CV Spain, JM Scarlett, K Houpt, "Longterm risks and benefits of early-age gonadectomy in dogs" JAVMA February 1, 2004.

9 CV Spain, JM Scarlett, K Houpt, "Longterm risks and benefits of early-age gonadectomy in cats," JAVMA February 1, 2004.

10 See note 1 above.

11 JL Grandy, CI Dunlop, "Anesthesia of pups and kittens," JAVMA 1991; 198:1177-182.



Paula Kislak, DVM, is a member of CHAI's Advisory Board and the President of the Association of Veterinarians for Animal Rights (AVAR). She performed the first research studies on early-age spaying and neutering with Dr. Mark Bloomberg. In 1998, Dr. Kislak introduced the concept of early age spay/neuter in Israel in a presentation, sponsored by CHAI, to Israeli veterinarians. This factsheet was excerpted by Paula Kislak from articles she wrote for Veterinary Practice News and the Veterinary Medical Association Journal of Israel.