[megansmomma]

Early Neuters

The pet overpopulation problem in the United States has reached enormous proportions. In 1987, for example, between 6.3 and 10.4 million dogs were euthanatized in shelters in the United Stales. Most animal care facilities have instituted mandatory neuter policies as an attempt to reduce the number of unowned and unwanted animals. They require that owners who adopt kittens and puppies have them neutered at five to eight months of age. As one would expect, follow-up and enforcement of these policies are difficult at best. Compliance rates average only 50 to 60 percent, with the result that many animals remain sexually intact and reproduce prolifically.

Current practice among veterinarians in the United States is to neuter puppies between five and eight months of age. However, there is little information in the veterinary literature regarding the optimal age for performing spays and castrations. Since some dogs reach sexual maturity prior to six months of age, a number of dogs are neutered after reaching sexual maturity and therefore, they may already have bred fertile females. For sterilization programs to be effective, all non-breeding animals should be neutered prior to the onset of puberty, and compliance rates must be improved.

Some animal shelters, in responding to these problems, have instituted early neuter programs. Under these programs, puppies and kittens are neutered before they leave the shelter, bringing compliance rates to 100 percent. Widespread adoption of early neuter programs by shelters will likely have a significant positive impact on the pet overpopulation problem.

Since the advent of early neuter programs, a number of questions have been raised regarding the appropriate age at which gonadectomy should be performed, as well as the safety of anesthetizing young puppies. Data on gonadectomy in immature dogs have recently been published, including anesthetic and surgical techniques and effects on behavioral and physical development. One study7, comparing the effects of neutering puppies at seven weeks versus seven months of age, found that neutering at either age produced similar effects on physical, skeletal and behavioral development. Gonadectomy did not affect food intake or weight gain, once again arguing against the idea that neutering animals predisposes them to obesity. Neutering did not result in inactivity or lethargy in this study; in fact, all neutered dogs were assessed by their caretakers to be more active than their sexually intact counterparts. They also found that prepubertal gonadectomy does not stunt growth; indeed, it contributes to growth enhancement!

Bone growth ceases when the physiologic growth plates located at the ends of immature bones "close." Growth plate closure of the radius and ulna (forelimb bones) occurred three months later (in seven-month-old neuters) to four months later (in seven-week-old neuters) in neutered puppies versus their sexually intact litter males. The result is that the forelimb bones of neutered puppies were a fraction of an inch longer than those of the unneutered pups.

Also of significance is the fact that the seven-week-old puppies in this study tolerated anesthesia well. Surgeons actually found that spaying the younger puppies was easier than spaying bitches at the traditional age due to the smaller amount of fat, within the abdomen and the relative lack of vasculature. Surgical time and risk of hemorrhage were greatly reduced.

The benefits of early neutering to dog breeders are obvious. By having pet quality puppies neutered before they leave for their new homes, breeders would no longer have to rely on their puppy buyers to carry out their wishes. Early neutering virtually guarantees that undesirable genes will not affect future generations, and it also pays heed to every responsible breeder's concern about the problem of pet overpopulation.

Some shelters and veterinarians in private practice are currently performing the early neuter procedure. But it's also important for breeders to understand why individual veterinarians may choose not to perform early neuters. An eight-week-old puppy is not just a smaller version of an eight-month-old puppy. There are important differences between the two in factors such as respiratory and cardiovascular physiology, drug metabolism and thermoregulation. Few practitioners have accumulated a significant amount of experience in anesthetizing very young puppies on a regular basis, since there are not many situations which call for it.

On the other hand, most practitioners have neutered many older puppies and young adults, feel comfortable with the anesthetic and surgical protocols they have developed, and may not want to change. These individuals may feel it is neither time- nor cost-efficient to develop new protocols for early neuters, unless they have a clientele composed substantially of breeders or other individuals who would be interested in such a program.

In my experience as a veterinarian, I am often able to alleviate people's fears about neutering and clear up their misconceptions by presenting the objective data discussed here. Responsible breeders can—and should—make the same effort to ensure that pet puppies are neutered. Fulfillment of this duty brings all of us closer to breeding fewer dogs and conquering the pet overpopulation problem.

Dog Owners' Observations

Between 1974 and 1980, • thousands of 8 to 12-week-old puppies were neutered at the Medford, Oregon, SPCA shelter. Did early neutering cause long-term undesirable after effects, as some people believed? Shelter personnel decided to find out for themselves by looking at the dogs in their area.

Questionnaires were sent out to owners of 200 randomly selected dogs aged 3 to 14 years that had been neutered when they were 6 to 12 weeks old. Identical questionnaires were also mailed to owners of 200 dogs that had not been neutered or had been neutered after 6 months of age.

Their responses (see the charts at right) were published in an article by Leo L. Lieberman, D.V.M., in the Journal of the American Veterinary Medical Association on September 1, 1987. Owners of both male and female dogs in this survey reported less aggressive behavior, weight gain and medical problems for those dogs neutered at an early age, as compared to those dogs that were sexually intact or neutered after, six months.—Elizabeth Bodner, D.V.M.

The results of the survey that asked owners to comment on after effects of neutering. Numbers on horizontal axis indicate: (1) owner not pleased; (2) undesirable sexual behavior of pet; (3) aggressive behavior of pet; (4) overweight pet; (5) medical problems with pet; (6) intelligence rating of pet. Taken from JAVMA, Vol. 191, No. 5, September 1, 1987.

Dr. Bodner is the executive editor of the GAZETTE.



References

1. Grandy JL, Dunlop CI. Anesthesia of pups and kittens. JAVMA 1991;198:1244-1249.

2. Hart BL. Effects of neutering and spaying on the behavior of dogs and cats: Questions and answers about practical concerns. JAVMA 1991;198:1204-1205.

3. Houpt KA. Coren B, Hintz et al. Effect of sex and reproductive status on sucrose preference, food intake, and body weight of dogs. JAVMA 1979; 174:1083-K185.

4. Johnston SD. Questions and answers on the effects of surgically neutering dogs and cats. JAVMA 1991; 198:1206-1213.

5. LeRoux PH. Thyroid status, oestradiol level, work performance and body mass of ovariectomised bitches and bitches bearing ovarian autotransplants in the stomach wall.JS Afr Vet Assoc 1977:48:115- 117.

6. Olson PN, Nett TM. Reproductive endocrinology and physiology of the bitch, in Morrow DA (ed.) Current Therapy in Theriogenology. 1986, W.B. Saunders, Philadelphia. 453-457.

7. Salmeri KR, Bloomberg MS, Scruggs SL, Shille V. Gonadectomy in immature dogs: Effects on skeletal, physical, and behavioral development. JAVMA 1991;198:1193-1203.

8. Salmeri KR, Olson PN, Bloomberg MS, Elective gonadectomy in dogs: A review. JAVMA 1991:198:1183-1191.

9. Johnston SD. Chapter 181, Male Reproductive System. In Slatter DH (ed.), Textbook of Small Animal Surgery, Volume 11. 1985, W. B. Saunders. Philadelphia. 2535-2545.

10. Thrusfield MV. Association between urinary incontinence and spaying in bitches. Vet Rec 1985,116:695.

Dr. Marrion is affiliated with Angell Memorial Animal Hospital in Boston