Research on neutering and spaying

Does neutering and spaying increase or decrease the risk of cancer in dogs and cats? Is early neutering and spaying safe? Research covering these neutering issues are in the following material. To spay or not to spay for overpopulation is mentioned in only one article. I would assume that everybody who has done rescue work and seen the beautiful animals put down because no home was able to be found for them strongly feel that one should neuter unless one is a responsible breeder. Please check your area as there are many resources for low cost spaying and neutering..http://http://www.spayusa.org/. Their 800 number is 1-800-248-spay.
  • The Question Of Neutering and at what age (written by Pam Davol of Wing-In-Wave Labradors, a noted research scientist and a Labrador genetic expert
    "With regard to cancer, spayed females have a 4 times greater risk for developing cardiac hemangiosarcomas (vascular tumors) compared to intact females (neutered males also show a significant increase in risk for these tumors compared to intact males) (Ware and Hysper, J. Vet. Intern. Med. 13:95-103, 1999.). Additionally, both neutered males and females have a 2-fold greater risk for developing bone tumors (osteosarcoma) compared to intact males and females (Ru et al., Vet J. 156:31-9, 1998.)."
  • Cancer Risks in Cats and Dogs By Theresa A. Fuess, Ph.D. Information Specialist University of Illinois College of Veterinary Medicine
    "Spaying and neutering can reduce the risk of cancer. Dogs spayed before the first heat cycle have only half the risk of mammary carcinoma of those spayed after the first but before the second heat cycle. Dogs spayed after the fifth heat cycle or never spayed have the highest risk of mammary cancer. Testicular carcinomas or tumors in dogs are common, but having your dog neutered eliminates that risk. Fortunately, testicular cancer rarely spreads in dogs, unlike in human beings, so treatment has a high success rate."
  • Review of the Epidemiology of Cancer in Dogs by Todd Bessinger
    "Interestingly, cancers of the ovaries and uterus are rare in dogs. This could be because most dogs do not reach the age at which these cancers become more common. "....."Purebred dogs are twice as likely to get breast cancer as are mixed breed dogs of the same age. The most important conclusion gained from examining studies of breast cancer in dogs is that early spaying protects against breast cancer.
    The greatest protection from spaying occurs if the dog is spayed before her first heat. The protective value of spaying drops steadily until age 2 1/2. If the bitch is spayed at or after age 2 1/2, the risk of getting breast cancer is statistically no different from a bitch which was never spayed. One study, however, found at least some protection from breast cancer when bitches were spayed up to five years of age. Clearly, however, the earlier a bitch is spayed, the less likely she is to get breast cancer... Unspayed bitches who were underweight as puppies have about half the risk of developing breast cancer as puppies who were of normal or above-normal weight. A related finding was that obese dogs with breast cancer were four times as likely to have more malignant, aggressive tumors than were dogs of normal weight. ....Dogs with undescended testicles (i.e., the testicles do not properly migrate to the scrotum but remain in the body cavity) have a markedly higher risk than other dogs to develop this type of cancer. Dogs with inguinal hernias are also at increased risk. Obviously, neutering of dogs prevents the development of this type of cancer....Osteosarcoma tends to affect larger breeds with a slight increase in incidence with age. Males are more likely to be affected than are females. And since neutered dogs and bitches have twice the risk of developing the disease as compared to intact dogs, hormonal factors are thought to play a role...Bladder cancers is dogs are more likely to occur in older dogs. Two studies found a one and one-half to threefold higher risk in females while a third study found no differences between the genders. This latter study did find that neutered dogs of both sexes seem to be at higher risk. " Z
  • Am J Epidemiol. 1991 Apr 1;133(7):694-703.
    Body conformation, diet, and risk of breast cancer in pet dogs: a case-control study.
    Sonnenschein EG, Glickman LT, Goldschmidt MH, McKee LJ.
    Department of Environmental Medicine, New York University Medical School, NY 10010.
    Canine and human breast cancer share several important clinical and histologic features. A case-control study of nutritional factors and canine breast cancer was conducted at the Veterinary Hospital of the University of Pennsylvania in 1984-1987 by interviewing owners of 150 pet dogs diagnosed with breast cancer, owners of 147 cancer control dogs, and owners of 131 noncancer control dogs. The risk of breast cancer was significantly reduced in dogs spayed at or before 2.5 years of age. Neither a high-fat diet nor obesity 1 year before diagnosis increased the risk of breast cancer according to multiple logistic regression analysis. However, the risk of breast cancer among spayed dogs was significantly reduced in dogs that had been thin at 9-12 months of age (odds ratio (OR) = 0.04 (95% confidence interval (CI) 0.004-0.4) and OR = 0.04 (95% CI 0.004-0.5) for cases vs. cancer controls and cases vs. noncancer controls, respectively, after adjustment for age at spay). Among intact dogs, the risk associated with being thin at 9-12 months of age was reduced, but not significantly so (OR = 0.60 (95% CI 0.2-1.9) and OR = 0.51 (95% CI 0.2-1.4) for the two comparisons, respectively). Results of this study suggest that nutritional factors operating early in life may be of etiologic importance in canine breast cancer
  • J Am Vet Med Assoc. 2004 Feb 1;224(3):380-7. : Long-term risks and benefits of early-age gonadectomy in dogs.
    Spain CV, Scarlett JM, Houpt KA.
    Department of Population Medicine and Diagnostic Science, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.

    OBJECTIVE: To evaluate the long-term risks and benefits of early-age gonadectomy, compared with traditional-age gonadectomy, among dogs adopted from a large animal shelter. DESIGN: Retrospective cohort study. ANIMALS: 1,842 dogs. PROCEDURE: Dogs underwent gonadectomy and were adopted from an animal shelter before 1 year of age; follow-up was available for as long as 11 years after surgery. Adopters completed a questionnaire about their dogs' behavior and medical history. When possible, the dogs' veterinary records were reviewed. Associations between the occurrence of 56 medical and behavioral conditions and dogs' age at gonadectomy were evaluated. RESULTS: Among female dogs, early-age gonadectomy was associated with increased rate of cystitis and decreasing age at gonadectomy was associated with increased rate of urinary incontinence. Among male and female dogs with early-age gonadectomy, hip dysplasia, noise phobias, and sexual behaviors were increased, whereas obesity, separation anxiety, escaping behaviors, inappropriate elimination when frightened, and relinquishment for any reason were decreased. CONCLUSIONS AND CLINICAL RELEVANCE: Because early-age gonadectomy appears to offer more benefits than risks for male dogs, animal shelters can safely gonadectomize male dogs at a young age and veterinary practitioners should consider recommending routine gonadectomy for client-owned male dogs before the traditional age of 6 to 8 months. For female dogs, however, increased urinary incontinence suggests that delaying gonadectomy until at least 3 months of age may be beneficial.
  • 1: J Am Vet Med Assoc. 2004 Feb 1;224(3):372-9. : Long-term risks and benefits of early-age gonadectomy in cats.
    Spain CV, Scarlett JM, Houpt KA.
    Department of Population Medicine and Diagnostic Science, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.

    OBJECTIVE: To evaluate the long-term risks and benefits of early-age gonadectomy, compared with traditional-age gonadectomy, among cats adopted from a large animal shelter. DESIGN: Retrospective cohort study. ANIMALS: 1,660 cats. PROCEDURE: Cats underwent gonadectomy and were adopted from an animal shelter before 1 year of age; follow-up was available for as long as 11 years after surgery (median follow-up time, 3.9 years). Adopters completed a questionnaire about their cats' behavior and medical history. When possible, the cats' veterinary records were reviewed. Statistical analyses were conducted to identify any associations between the occurrence of 47 medical and behavioral conditions and the cats' age at gonadectomy. RESULTS: Among male cats that underwent early-age gonadectomy (< 5.5 months of age), the occurrence of abscesses, aggression toward veterinarians, sexual behaviors, and urine spraying was decreased, whereas hiding was increased, compared with cats that underwent gonadectomy at an older age. Among male and female cats that underwent early-age gonadectomy, asthma, gingivitis, and hyperactivity were decreased, whereas shyness was increased. CONCLUSIONS AND CLINICAL RELEVANCE: Gonadectomy before 5.5 months of age was not associated with increased rates of death or relinquishment or occurrence of any serious medical or behavioral condition and may provide certain important long-term benefits, especially for male cats. Animal shelters can safely gonadectomize cats at a young age, and veterinarians should consider recommending routine gonadectomy for client-owned cats before the traditional age of 6 to 8 months.
  • J Am Vet Med Assoc. 2001 Jan 15;218(2):217-21. : Long-term outcome of gonadectomy performed at an early age or traditional age in dogs.
    Howe LM, Slater MR, Boothe HW, Hobson HP, Holcom JL, Spann AC.
    Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4474, USA.

    OBJECTIVE: To determine long-term results and complications of gonadectomy performed at an early age (prepubertal) or at the traditional age in dogs. DESIGN: Cohort study. ANIMALS: 269 dogs from animal shelters. PROCEDURE: Dogs that underwent gonadectomy were allotted to 2 groups on the basis of estimated age at surgery (traditional age, > or =24 weeks old; prepubertal, < 24 weeks old). Adoptive owner information was obtained from shelter records, and telephone interviews were conducted with owners to determine physical or behavioral problems observed in the dogs since adoption. Follow-up information was obtained from attending veterinarians for dogs with complex problems or when owners were uncertain regarding the exact nature of their dog's problem. RESULTS: Prepubertal gonadectomy did not result in an increased incidence of behavioral problems or problems associated with any body system, compared with traditional-age gonadectomy, during a median follow-up period of 48 months after gonadectomy. Rate of retention in the original adoptive household was the same for dogs that underwent prepubertal gonadectomy as those that underwent traditional-age gonadectomy. Infectious diseases, however, were more common in dogs that underwent prepubertal gonadectomy. CONCLUSIONS AND CLINICAL IMPLICATIONS: 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.
  • 1: J Am Vet Med Assoc. 2000 Dec 1;217(11):1661-5. : Erratum in: J Am Vet Med Assoc 2001 Jan 15;218(2):221.
    Long-term outcome of gonadectomy performed at an early age or traditional age in cats.
    Howe LM, Slater MR, Boothe HW, Hobson HP, Fossum TW, Spann AC, Wilkie WS.
    Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4474, USA.

    OBJECTIVE: To determine long-term results and complications of gonadectomy performed at an early age (prepubertal) or at the traditional age in cats. DESIGN: Cohort study. ANIMALS: 263 cats from animal shelters. PROCEDURE: Cats that underwent gonadectomy were allotted to 2 groups on the basis of estimated age at surgery (traditional age, > or = 24 weeks old; prepubertal, < 24 weeks old). Adoptive owner information was obtained from shelter records, and telephone interviews were conducted with owners to determine physical or behavioral problems observed in the cats after adoption. Follow-up information was obtained from attending veterinarians for cats with complex problems or when owners were uncertain regarding the exact nature of their cat's problem. RESULTS: Compared with traditional-age gonadectomy, prepubertal gonadectomy did not result in an increased incidence of infectious disease, behavioral problems, or problems associated with any body system during a median follow-up period of 37 months. Additionally, the rate of retention in the original adoptive household was the same for cats that underwent prepubertal gonadectomy as those that underwent traditional-age gonadectomy. CONCLUSIONS AND CLINICAL RELEVANCE: 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.
  • 1: Clin Tech Small Anim Pract. 2002 Aug;17(3):124-8. Related Articles, Links Early spay-neuter: clinical considerations. Kustritz MV. Department of Small Animal Clinical Sciences, University of Minnesota College of Veterinary Medicine, 1352 Boyd Avenue, St. Paul, MN 55108, USA.
    Early spay-neuter is ovariohysterectomy or castration of puppies or kittens 6 to 14 weeks of age. Pediatric animals may have an enhanced response to relatively low doses of anesthetic agents. Animals should be fasted no more than 3 to 4 hours before surgery to prevent hypoglycemia, and hypothermia should be avoided. Heart and respiratory rates must be monitored carefully throughout anesthesia. Pediatric gonadectomy surgeries are quick with minimal bleeding. Anesthetic recovery is rapid. No significant short-term or long-term effects have been reported. Prepuberal gonadectomy is most useful for humane organizations and conscientious breeders wishing to preclude reproduction of pet dogs and cats while placing animals at a young enough age to optimize socialization and training.
  • 1: J Vet Med Educ. 2003 Winter;30(4):372-8. : Determinants of adoption and euthanasia of shelter dogs spayed or neutered in the university of california veterinary student surgery program compared to other shelter dogs.
    Clevenger J, Kass PH.
    Public Health Program, University of California, Davis, CA 95616, USA.

    Limited economic resources and pet overpopulation force animals shelters to consider euthanasia of adoptable animals every day. Veterinary medical schools can play a positive role in increasing pet adoption and combating overpopulation by providing free neutering for shelter animals. This retrospective cohort study illustrated that the cooperative efforts of a veterinary medicine surgical teaching program and local animal shelters decreases euthanasia of adoptable pets. At the University of California, Davis (UCD), shelter dogs are neutered by veterinary students and then returned to the shelter for adoption. The rates of adoption and euthanasia of the dogs neutered at UCD were contrasted with a comparison shelter group to determine the effect of pre-adoption neutering. The UCD-neutered dogs had a lower rate of euthanasia than the comparison shelter group at the shelters investigated. At Sacramento County Animal Care and Regulation, 73% of the UCD group but only 36% of the comparison group were adopted. At Yolo County Animal Services, 71% of the UCD group and 45% of the comparison group were adopted. The sex of an animal did not significantly affect the rate of euthanasia. Dogs that were predominantly pit bull, rottweiler, or chow chow breeds had higher rates of euthanasia than other breeds, independent of neuter status. Also, juveniles (less than one year old) had lower rates of euthanasia than adults, independent of neuter status. UCD adult dogs had lower rates of euthanasia than comparison adults. Post-surgical UCD dogs spent a longer average time in the shelter before adoption (15 days at Sacramento; 16 days at Yolo) than the comparison dogs (11 and 12 days, respectively). UCD dogs also spent a longer average time in the shelter before euthanasia (18 and 25 days, respectively) than the comparison dogs (13 days at both shelters). Lower probabilities of euthanasia for behavioral or medical reasons were found for UCD dogs than for the comparison dogs. The probability of euthanasia for reasons of space limitations increased with time in shelter for both groups. In this study, pre-adoption neutering increased adoptions without increasing the probability of medical or behavioral euthanasia
  • : J Am Anim Hosp Assoc. 2002 Sep-Oct;38(5):482-8. : When to neuter dogs and cats: a survey of New York state veterinarians' practices and beliefs.
    Spain CV, Scarlett JM, Cully SM.
    Department of Population Medicine and Diagnostic Science, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.

    Practicing veterinarians in small-animal or mixed-animal practice in New York state were surveyed about their beliefs and practices regarding the age at which dogs and cats should be neutered and their attitudes toward early neutering (at 4 months of age or younger). The majority of veterinarians routinely recommended neutering for all client animals (70.6%) and supported the routine neutering of shelter animals before adoption (90.3%). More veterinarians in this study reported at least one perceived benefit (91.3%) for early neutering than reported at least one perceived risk (84.4%). Veterinarians with experience neutering early were less likely to believe that the procedure was associated with one or more risks.
  • 1: J Reprod Fertil Suppl. 2001;57:233-6. : The relationship of urinary incontinence to early spaying in bitches.
    Stocklin-Gautschi NM, Hassig M, Reichler IM, Hubler M, Arnold S.
    Department of Reproduction, Veterinary Faculty of Zurich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland.

    It is still controversial whether a bitch should be spayed before or after the first oestrus. It would be desirable to spay bitches at an age that would minimize the side effects of neutering. With regard to the risk of mammary tumours, early spaying must be recommended because the incidence of tumours is reduced considerably. The aim of the present study was to determine whether early spaying also reduces the risk of urinary incontinence. The owners of 206 bitches that had been spayed before their first oestrus and for at least 3 years were questioned on the occurrence of urinary incontinence as a result of spaying. At the time of the enquiry the average age of the bitches was 6.5 years, and the average age at the time of surgery was 7.1 months. Urinary incontinence after spaying occurred in 9.7% of bitches. This incidence is approximately half that of spaying after the first oestrus. Urinary incontinence affected 12.5% of bitches that were of a large body weight (> 20 kg body weight) and 5.1% of bitches that were of a small body weight (< 20 kg body weight). The surgical procedure (ovariectomy versus ovariohysterectomy) had no influence on the incidence, or on the period between spaying and the occurrence of urinary incontinence. Urinary incontinence occurred on average at 2 years and 10 months after surgery and occurred each day, while the animals were awake or during sleep. However, compared with late spaying the clinical signs of urinary incontinence were more distinct after early spaying.
  • 1: J Reprod Fertil Suppl. 2001;57:223-32. : Early-age neutering of dogs and cats in the United States (a review).
    Olson PN, Kustritz MV, Johnston SD.
    Guide Dogs for the Blind, Inc, 350 Los Ranchitos Road, San Rafael, CA 94903, USA.

    Prepubertal gonadectomy, often referred to as early-age neutering, has increased in popularity in the United States. The procedure is often used at animal care and control facilities, where puppies and kittens are neutered as early as 7 weeks of age or before adoption. Although the anaesthetic and surgical procedures appear to be safe, studies continue to evaluate the long-term effects on health and behaviour. Early-age neutering is one technique that is used to combat pet overpopulation, a problem whereby millions of unwanted healthy dogs and cats are euthanased each year. Although neutering animals is helpful in controlling pet overpopulation, other factors must be considered. In addition, many animals are relinquished to shelters when they show inappropriate behaviours, because owners and veterinarians are unable to modify animal behaviour. This review discusses early-age neutering in the United States, and includes the review of scientific studies that have evaluated this procedure in puppies and kittens. Early-age neutering does not stunt growth in dogs or cats (a once-held belief), but may alter metabolic rates in cats. The anaesthetic and surgical procedures are apparently safe for young puppies and kittens; morbidity is lower and recovery is faster than in adult animals. To date, adverse side effects are apparently no greater in animals neutered at early ages (7 weeks) than in those neutered at the conventional age (7 months). 1: J Small Anim Pract. 1998 Dec;39(12):559-66. : Acquired urinary incontinence in bitches: its incidence and relationship to neutering practices.
    Thrusfield MV, Holt PE, Muirhead RH.
    Department of Veterinary Clinical Studies, University of Edinburgh, Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian.

    A five-year cohort study was conducted on bitches chosen by a sample of 233 randomly selected practising veterinary surgeons in the UK, to estimate the incidence of acquired urinary incontinence (AUI) in neutered and entire animals, and to investigate possible risk factors associated with neutering practices. Information was collected using questionnaires, and data on 809 bitches, of which 22 developed AUI, were obtained. The estimated incidence rates in neutered and entire animals were 0.0174 and 0.0022 per animal-year, respectively (95 per cent confidence intervals: 0.0110, 0.0275 and 0.0009, 0.0058, respectively). The relative risk, neutered vs entire, was 7.8 (95 per cent confidence interval: 2.6, 31.5). The attributable proportion(exposed) and population attributable proportion were 87.1 per cent and 63.1 per cent (95 per cent confidence intervals: 61.9 per cent, 95.6 per cent, and 28.3 percent, 88.5 per cent, respectively). An increased risk, significant at the conventional 5 per cent level, was not demonstrated in animals neutered before, vs after, first heat (relative risk: 3.9, 95 per cent confidence interval: 0.8, 10.4), although the result was significant at the 10 per cent level. Removal of the cervix was not shown to be a risk factor in neutered dogs.
  • 1: Vet Rec. 2003 Apr 19;152(16):502-4. : Incidence of cryptorchidism in dogs and cats.
    Yates D, Hayes G, Heffernan M, Beynon R.
    RSPCA Greater Manchester Animal Hospital, 411 Eccles New Road, Salford M5 5NN.

    Over a period of 54 months, 3518 dogs and 3806 cats were castrated; 240 of the dogs and 50 of the cats were cryptorchid. Pedigree dogs, in particular the German shepherd dog, boxer and chihuahua were over-represented. Among the dogs, right-sided inguinal cryptorchidism was the most common form, followed by right-sided abdominal cryptorchidism. The location of the affected testicle(s) was most variable in the boxer. Among the cats, left- or right-sided inguinal cryptorchidism were the most common forms of the condition.
  • 1: J Appl Anim Welf Sci. 2002;5(3):203-13. : Body condition of feral cats and the effect of neutering.
    Scott KC, Levy JK, Gorman SP, Newell SM.
    College of Veterinary Medicine, University of Florida, Gainesville, USA.

    Considerable debate exists regarding the most appropriate methods for controlling feral cat populations, both from humane and logistical points of view. The physical condition of feral cats has not been reported, and it is not known if these cats benefit from neutering. This study investigates the body condition of feral cats by measuring body weight (BW), body condition score (BCS; Burkholder, 2000; Laflamme, Kealy, & Schmidt, 1994), and falciform fat pad. The study includes lateral abdominal radiographs taken at the time of neutering of 105 adult feral cats for measurement of falciform fat pad depth and area. At that time we also assessed BW and BCS. One year later we assessed the effects of neutering on body condition by evaluating a subsample of 14 cats. At the time of surgery, the cats were lean but not emaciated (BW 3.1 +/- 0.9 kg; BCS 4 +/- 1; based on a 1 to 9 scale ranging from 1 [emaciated] to 9 [grossly obese]). Falciform fat pad depth and area averaged 7.1 mm and 197.4 mm2, respectively, indicating a small amount of fat. Fourteen cats, reevaluated 1 year after neutering, increased 260% + 90% in falciform fat pad depth, 420% +/- 390% in fat pad area, 40% +/- 4% in BW, and 1 level in BCS ranking (1 to 9 scale; all differences p <.001). Similar to confined socialized cats, feral cats gained significant weight and body fat after neutering.
  • 1: J Anim Physiol Anim Nutr (Berl). 2001 Aug;85(7-8):195-9. Related Articles, Links Leptin, body fat content and energy expenditure in intact and gonadectomized adult cats: a preliminary study. Martin L, Siliart B, Dumon H, Backus R, Biourge V, Nguyen P. Laboratory of Nutrition and Endocrinology, National Veterinary School of Nantes, Nantes France.
    The present study was conducted to assess the body composition, leptin, and energy expenditure changes following gonadectomy in cats. Twenty-one females (12 intact and nine spayed) and 21 males (11 intact and 10 castrated) were used. Body weight was recorded. Serum plasma leptin was measured by radioimmunoassay and body composition and energy expenditure were assessed after injection of doubly labelled water. These results confirmed the gain in body weight and body fat following neutering and demonstrated a strong linear relationship between body fat and serum level of leptin. Energy expenditure decreased in castrated cats in comparison with intact ones. This study underlined the effect of gonadectomy as a major factor of obesity in cats and showed that the increase in circulating leptin reflected the amount of body fat. The present results provide further evidence that the regimen of gonadectomized cats should be carefully controlled to avoid excessive weight gain.
  • 1: J Am Vet Med Assoc. 2001 Jul 1;219(1):51-6. : Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs.
    Hart BL.
    Behavior Service, Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.

    OBJECTIVE: To determine whether gonadectomy predisposes dogs to development of age-related behavioral changes linked to cognitive impairment. DESIGN: Cohort study. ANIMALS: 29 sexually intact male dogs, 63 spayed female dogs, and 47 castrated male dogs 11 to 14 years old. PROCEDURE: Information on possible impairments in 4 behavioral categories linked to cognitive impairment (orientation in the home and yard, social interactions, house training, and sleep-wake cycle) was obtained from owners of the dogs by use of a structured telephone interview format. A second interview was performed 12 to 18 months after the initial interview, and differences in responses were evaluated. RESULTS: Sexually intact male dogs were significantly less likely than neutered dogs to progress from mild impairment (i.e., impairment in 1 category) to severe impairment (i.e., impairment in > or = 2 categories) during the time between the first and second interviews. This difference was not attributable to differences in ages of the dogs, duration of follow-up, or the owners' perceptions of the dogs' overall health. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the presence of circulating testosterone in aging sexually intact male dogs may slow the progression of cognitive impairment, at least among dogs that already have signs of mild impairment. Estrogens would be expected to have a similar protective role in sexually intact female dogs; unfortunately, too few sexually intact female dogs were available for inclusion in the study to test this hypothesis. There may be a need to evaluate possible methods for counteracting the effects of loss of sex hormones in gonadectomized dogs.
  • J Am Vet Med Assoc. 1997 Jul 15;211(2):180-2. : Effects of castration on problem behaviors in male dogs with reference to age and duration of behavior.
    Neilson JC, Eckstein RA, Hart BL.
    Behavior Service, Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis 95616, USA.

    OBJECTIVE: To determine whether 9 problem behaviors in adult male dogs were affected by castration and to examine the influence of age and duration of problem behavior on behavioral effects of castration. DESIGN: Cohort study. ANIMALS: 57 male dogs > 2 years old at the time of castration that had > or = 1 of the targeted problem behaviors. PROCEDURE: Data were collected by telephone contact with owners to identify dogs that had > or = 1 problem behavior before castration and to estimate the improvement (ie, decrease) in the objectionable behaviors after castration. Problem behaviors of interest included urine marking in the house, mounting, roaming, fear of inanimate stimuli, aggression toward human family members, aggression toward unfamiliar people, aggression toward other dogs in the household, aggression toward unfamiliar dogs, and aggression toward human territorial intruders. RESULTS: Effects of castration on fear of inanimate stimuli or aggression toward unfamiliar people were not significant. For urine marking, mounting, and roaming, castration resulted in an improvement of > or = 50% in > or = 60% of dogs and an improvement of > or = 90% in 25 to 40% of dogs. For remaining behaviors, castration resulted in an improvement of > or = 50% in < 35% of dogs. Significant correlations were not found between the percentage of improvement and age of the dog or duration of the problem behavior at the time of castration. CLINICAL IMPLICATIONS: Castration was most effective in altering objectionable urine making, mounting, and roaming. With various types of aggressive behavior, including aggression toward human family members, castration may be effective in decreasing aggression in some dogs, but fewer than a third can be expected to have marked improvement. Age of the dog or duration of the problem behavior does not have value in predicting whether castration will have a beneficial effect.
  • 1: J Am Vet Med Assoc. 1997 Jul 1;211(1):57-62. : Comment in: J Am Vet Med Assoc. 1997 Aug 15;211(4):408-9.
    Short-term results and complications of prepubertal gonadectomy in cats and dogs.
    Howe LM.
    Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4474, USA.

    OBJECTIVE: To determine short-term results and complications of prepubertal gonadectomy in cats and dogs. DESIGN: Prospective randomized study. ANIMALS: 775 cats and 1,213 dogs. PROCEDURE: Animals undergoing gonadectomy were allotted into 3 groups on the basis of estimated age (group 1, < 12 weeks old; group 2, 12 to 23 weeks old; group 3, > or = 24 weeks old). Complications during anesthesia, surgery, and the immediate postoperative period (7 days) were recorded. Complications were classified as major (required treatment and resulted in an increase in morbidity or mortality) or minor (required little or no treatment and caused a minimal increase in morbidity). An ANOVA was used to detect differences among groups in age, weight, body temperature, and duration of surgery. To detect differences in complication rates among groups, chi 2 analysis was used. RESULTS: Group 1 consisted of 723 animals, group 2 consisted of 532, and group 3 consisted of 733. Group-3 animals had a significantly higher overall complication rate (10.8%) than group-1 animals (6.5%), but did not differ from group-2 animals (8.8%). Differences were not detected among the 3 groups regarding major complications (2.9, 3.2, and 3.0% for groups 1, 2, and 3, respectively), but group-3 animals had significantly more minor complications (7.8%) than group-1 animals (3.6%), but not group-2 animals (5.6%). CLINICAL IMPLICATIONS: In this study, prepubertal gonadectomy did not increase morbidity or mortality on a short-term basis, compared with gonadectomy performed on animals at the traditional age. These procedures may be performed safely in prepubertal animals, provided that appropriate attention is given to anesthetic and surgical techniques.
  • 1: Res Vet Sci. 1997 Mar-Apr;62(2):131-6. : Effects of neutering on bodyweight, metabolic rate and glucose tolerance of domestic cats.
    Fettman MJ, Stanton CA, Banks LL, Hamar DW, Johnson DE, Hegstad RL, Johnston S.
    Department of Pathology, Colorado State University, Fort Collins 80523-1671, USA

    Few controlled studies have been made of the possible mechanisms and physiological consequences of weight gain after cats have been neutered. In this study, six male and six female cats were gonadectomised and compared with five entire male and six entire female cats, before they were neutered and one and three months later. The neutered males gained significantly more weight (mean [SEM] per cent) than the entire males (30.2 [5.2] v 11.8 [2.3]) and the entire females gained 40.0 (7.3) v 16.1 (3.3) per cent, (P < 0.05). The castrated males gained more weight as fat than the sexually intact males (22.0 [3.3] v 8.8 [4.5] per cent, P < 0.05). There was a significant increase (P < 0.05) in daily food intake after neutering. Spayed females underwent a significant decrease in fasting metabolic rate (83.7 [5.5] v 67.2 [2.3] kcal/kg bodyweight0.75/day P < 0.05). Gonadectomy had minimal effects on serum thyroid hormone concentrations, the resting or fasting metabolic rates in males, or on indices of glucose tolerance.