The study population was 96 intact males, neutered males, 63 intact females, and spayed females for a total sample of cases. In intact males and females, the occurrences of joint disorders were zero and 2 percent, respectively. In neutered males and females, there was no evident increased occurrence of joint disorders. The level of occurrence of one or more cancers in intact males was 6 percent and in intact females, 8 percent.
Neutering males and females did not lead to any evident increase in risk of a cancer. There were no cases of MC in females left intact or spayed at any time, and there was a 5 percent occurrence of PYO in the intact females. The study population was intact males, neutered males, intact females, and spayed females for a total sample of cases. Joint disorders are a major concern in this breed with 8 percent of intact males and 16 percent of intact females having one or more joint disorders.
The cancers followed occurred in the intact males and females at 16 and 11 percent, respectively. These relatively high occurrences of cancers in intact males and females were not increased by neutering at any age. Of females left intact or spayed at 2—8 years, 8 and 5 percent were diagnosed with MC, respectively. In intact females, 12 percent were diagnosed with PYO. The suggested guideline for males, given the risk of joint disorders for those neutered at mo.
The study population was 26 intact males, 27 neutered males, 18 intact females, and 23 spayed females for a total sample of 94 cases. This breed was chosen because of the large size.
In intact males and females, the occurrences of one or more joint disorders were 8 percent and 6 percent, respectively. The cancers followed occurred in intact males and females at 4 and 11 percent, respectively. With neutering males and females, there were no noteworthy increases in cancers. There was no occurrence of MC in either the intact or spayed females. Lacking a noticeable occurrence of increased joint disorders or cancers in neutered males those wishing to neuter should decide on the appropriate age.
However, given the large body size, some may wish to consider neutering well-beyond 1 year of age. The study population was 31 intact males, 30 neutered males, 20 intact females, and 52 spayed females for a total sample of cases.
There were no joint disorders in intact males and just one in the intact females. The occurrence of cancers in intact males was 6 percent and in intact females, zero.
There were no evident increases in cancers in neutered males or females. There was no occurrence of MC in intact or spayed females and a 14 percent occurrence of PYO in intact females.
Spaying at mo. However, to avoid the high level of UI occurrence in females, one could consider spaying females at, or beyond, 2 years. The study population was intact males, neutered males, 77 intact females, and spayed females for a total sample of cases.
In this small-dog breed there were no occurrences of joint disorders in either intact or neutered males and females, revealing virtually no vulnerability in this regard. There was no occurrence of the cancers followed in intact males and females.
In neutered males there was no occurrence of cancers. However, in females, the occurrence of cancers for those spayed at mo. MC occurred in 3 percent of intact females.
PYO occurred in 5 percent of intact females. UI was not reported in any females. The picture is very different for spaying females where the increased risk of cancers started with spaying at mo. The suggested guideline for females is to delay spaying until the female is 2 years of age.
Another possibility is to spay a female a month or two before 6 months to avoid the increased risk of cancers. The study population was 35 intact males, 33 neutered males, 28 intact females, and 46 spayed females for a total sample of cases. Just one intact male had a joint disorder, and other than this, no joint disorders were reported in intact females or in neutered males or females.
None of the intact males or females had any of the cancers followed. There were no noteworthy occurrences of the cancers in neutered males or females. There were no occurrences of MC in either intact or neutered females, and a 7 percent occurrence of PYO in intact females. However, for females, one could consider delaying spaying until a year of age to avoid the risk of UI.
There were no joint disorders reported in intact males, and in intact females, just 1 percent. In neutered males and females there were no noteworthy occurrences of joint disorders. In intact males and intact females, just 1 percent were reported with at least one of the cancers followed.
In both neutered males and females, none of the cancer occurrences was noteworthy. In intact females, the occurrence of MC was 1 percent as was the occurrence with spaying at 2—8 years.
PYO was reported in 7 percent of intact females. No UI was reported in any of the intact or spayed females. Since the reporting from this center of increased risks of joint disorders and some cancers in Golden Retrievers, Labrador Retrievers, and German Shepherd Dogs 11 — 13 , the appropriate age of neutering has become a common point of discussion 16 — With the evidence-based information on the risks, if any, of joint disorders, cancers, PYO and UI associated with neutering at different ages for males and females of various as dog breeds, dog owners, and their veterinarians, can use this information to select an age for neutering for the long-term health of their companion dogs on a case-by-case basis.
The overall major finding from the present study is that there are breed differences — and sometimes sex differences — with regard to the increased risks of joint disorders and cancers associated with neutering at various ages.
For example, with the Boston Terrier, neutering females at the standard 6 month age did not increase the risks of joint disorders or cancers over that of dogs left intact, but with males, neutering before a year of age was associated with a significant increase in cancers.
The opposite effect with genders was seen in the Cocker Spaniel where neutering at 6 months was not associated with an increase in joint disorders or cancers in males, but in females there was a significant increase in risk of cancers to 17 percent with neutering before 2 years. Another important finding that holds across several breeds is that with the small-dog breeds — Cavalier King Charles Spaniel, Chihuahua, Corgi, Dachshund, Maltese, Pomeranian, Poodle-Toy, Pug, Shih Tzu, Yorkshire Terrier —the occurrences of joint disorders were close to zero in both the intact and neutered males and females.
In these small-dog breeds, the occurrence of cancers was low in both those kept intact and neutered. Two exceptions were the Boston Terrier and Shih Tzu where there was there a significant increase in cancers with neutering. As noted in the results section, the mean date of last entry per patient in the hospital record ranged from about 4. The perspective taken here is that it is the early occurring joint disorders and cancers that are the most impactful on the human caregivers, both emotionally and financially, as well as their dogs.
To just delay neutering by a year or so to lower the risk of a joint disorder or cancer in those breeds where the issue is relevant, is a noteworthy goal, making it worthwhile to discuss appropriate ages to neuter with caregivers who have a new puppy. A suggested guideline for the use of the data presented here for those who may wish to focus on a breed or two, is to first scroll through Table 1 to peruse the breeds for a brief look at the neutering guidelines for the breeds of interest.
The next step could be to refer to summary paragraphs in the Results section, which present the major findings with a suggested guideline for neutering age. Our intention is to offer readers data-based information to make case-by-case decisions about age of neutering. As is clearly evident in the breed-specific data presented, one cannot make a generalization for all dogs about age of neutering guidelines.
As mentioned, this study involved 35 breeds, counting the three varieties of Poodles as three breeds. Thus, most breeds registered by AKC or other comparable agencies were not covered. The breeds chosen were the most popular, and with the largest dataset in our records, or were included to sample the largest range of breed sizes as was feasible.
Hence, some of the largest breeds e. While with some of the most popular breeds there were over 1, cases in the database, most breeds ended up with to cases which was sufficient for statistical analyses where the impact of neutering was substantial. A suggestion for those interested in a breed not covered in this study is to find a breed or two closest genetically to the breed of their interest in order to get an estimate of the various disease risks, if any, associated with neutering.
However, one needs to bear in mind that even genetically related breeds may vary a great deal. An example is seen when comparing Golden and Labrador Retrievers, using the data from this study, where in the Labrador, there was no increase in cancer risk above that of intact dogs with neutering, but in the female Golden, the risk of a cancer with neutering increased to 2—4 times that of the 5 percent level of intact females.
The popular Poodle breed provides another example, where there are three major varieties in size, the Standard, Miniature, and Toy. In the Standard, neutering males at 1 year was associated with a highly significant increase in the risk of a cancer mainly LSA to over six times that of intact males, whereas in the Miniature, there was no increase in cancers with neutering but a significant increase in joint disorders mainly CCL with neutering at mo.
A likely mechanism by which early neutering may lead to a joint disorder is related to disturbance of the closure of the long-bone growth plates by gonadal hormone secretion as the animal approaches maturity 19 , We have proposed that neutering much before the closure of growth plates allows the long bones to grow a little longer than normal, and may sufficiently disturb joint alignments in some neutered dogs to lead to a clinically-apparent joint disorder.
Given the frequency with which early neutering is performed in dogs, it seems surprising that osteoporosis has not been examined given that in humans, chronic loss of gonadal hormones is associated with osteoporosis It could be that the wolf ancestor of the dog had one breeding season and that the bone structure of mature dogs was not as affected by seasonal fluctuations of gonadal hormones as with a permanent gonadal hormonal loss in humans.
One of the frequently mentioned advantages of early neutering of female dogs is protection against MC There may be important genetic, breed-line differences in the occurrence of MC that are not portrayed in our database. However, relevant to the discussion of MC is the recent meta-analysis of published studies on neutering females and MC, finding that the evidence linking neutering to a reduced risk of MC is weak In the data gathered in this study, through 11 years of age, the occurrence of MC in females left intact was rarely above 6 percent and frequently 2 percent or less.
Obviously with most cases of intact females not followed through 11 years, and with the year cut-off for those that were followed, many occurrences of MC were missed. However, it seems reasonable, that if MC was a common occurrence in intact females that this disease would have been more frequent in the intact females followed. Further, a very late onset of MC would seem less disturbing to pet owners than the much earlier onsets of joint diseases and other cancers.
For males, there is some concern that neutering beyond puberty will increase the likelihood of a problem behavior such as aggression. However, studies show that while neutering males can reduce aggression to people or other dogs in about 25 percent of males, neutering prior to puberty is no more effective in preventing this problem than is neutering in adulthood in resolving the problem 24 , This paper deals primarily with the risks of diseases that are seen within a given breed and sex.
Comparisons between breeds are difficult to interpret, in part because of differences in developmental and physiological factors between breeds including those between smaller and larger breeds.
In the text we have reported the occurrences of various diseases in percentages but in statistical analyses the actual data are used. When disease incidence is particularly low in one or more neutering subgroups, the ability to detect significant differences will be low, but there still could be differences which may or may not have been evident in the statistical analyses. There are at least two major limitations to this study.
First, relatively few breeds are covered compared to those included in the various breed registries of kennel clubs and canine organizations. This limitation was necessary so as to apply the same diagnostic criteria for diseases covered across all breeds, using the same database, and the necessity of having sufficient cases for analyses.
Second, no information is available as to the reasons the owners or others chose to neuter, or not to neuter their dogs. In California, the vast majority of dogs are neutered, and since it is legally required for dogs to be neutered prior to adoption from an animal shelter or humane society 26 ; many breeders impose the same requirement. In conclusion, the data presented should provide to veterinarians and interested puppy caregivers data-based information for the best age for neutering to avoid increasing the risk of joint disorders and some cancers beyond that of leaving the dog intact.
Readers can note that an elevated risk for a joint disorder or cancer occurs in relatively few of these breeds. In other words, with most breeds or sexes, neutering can apparently be done without referral to a particular age, at least with regard to the joint disorders or cancers covered in this study.
Of course, individual factors must be taken into account. For puppies of mixed breed, another paper that is currently in press provides data-based information dealing with age of neutering and the risk of one or more joint disorders as a function of the dog adult weight category This information can also help inform decisions on age of recommended neuter in purebred dogs where the breed is not covered in our data.
The datasets presented in this study can be found in online repositories. NW: statistical analyses. All authors contributed to the article and approved the submitted version. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Epidemiology of surgical castration of dogs and cats in the United States.
J Am Vet Med Assoc. Prevalence of, and risk factors for, hip dysplasia and cranial cruciate ligament deficiency in dogs.
Breed, sex, and body weight as risk factors for rupture of the cranial cruciate ligament in young dogs. PubMed Abstract Google Scholar. Dorn M, Seath IJ. Neuter status as a risk factor for canine intervertebral disc herniation IVDH in dachsunds: a retrospective cohort study. Canine Genet Epidemiol. Hormonal and sex impact on the epidemiology of canine lymphoma. J Cancer Epidemiol. Benefits that female dogs can see from having spay surgery when they are closer to maturity include lower risk of orthopedic issues, a reduced risk of cancers especially breast cancer , and a reduced risk of urinary incontinence.
We recommend waiting until your dog is at least over 6 months and likely even older for larger dogs. The benefits are much more pronounced in larger dogs, but there is not a lot of difference for lap dogs. Studies have shown that large dogs spayed before 6 months of age experience some higher risk of orthopedic problems and certain cancers and that risk is statistically reduced at 12 months.
What happens statistically at each age in between still needs more study. We do know that with each heat cycle there is an increased risk of mammary adenocarcinoma breast cancer and risk of pyometra a life-threatening uterine infection requiring emergency surgery and intensive care.
If we are able to allow female dogs to get as old as possible, but manage to spay them just before their first heat, this would seem like the ideal situation, but it is tricky to predict when that first heat will be. Knowing the family history can be helpful, but is still not an exact way to know when the first heat will occur.
Facebook Instagram. Spaying to prevent genetic diseases Unless your dog is a perfect representative of the breed, there is a possibility of spreading genetic conditions such as hip dysplasia , cardiac diseases, orthopedic and skin conditions. Inbreeding has led to a lot of suffering in our canine patients, and it means that the guardians may incur additional veterinary expenses trying to fix the problem. Spaying to prevent heat cycles Living through a heat cycle is not always the most fun.
Female dogs bleed during their heat cycles, and you need to be prepared for the consequences, especially if you have plush white carpet Spaying to prevent false pregnancy False pregnancy, a. The reason for this strange and stressful behavior may be a hormonal imbalance, and therefore the definitive treatment is to spay the dog, i. Think of it as a small investment that will pay dividends for the rest of her life. Questions to ask your veterinarian:. If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.
Skip to main content. And significantly, those behavioral improvements were equally likely if neutering was delayed until after a dog had reached sexual maturity. Neutering also does not prevent prostate cancer.
Meanwhile, Dr. And testicular cancer, though a more common occurrence in older intact male dogs, offers better treatment outcomes compared to other cancers. So what should dog owners do? Should you spay or neuter, and if so, when? Hart agrees. While you make that calculation, bear in mind a reminder from Dr. Hart: although the risk of developing certain cancers and joint disorders increased when certain breeds were spayed or neutered early, most dogs will not develop these conditions.
The emerging research can give us a picture of the likelihood of certain outcomes, but can never fully predict what life will look like for your particular dog. Have a non-urgent question for a veterinarian? Compare Breeds Compare up to 5 different breeds side by side. Dog Name Finder Browse our extensive library of dog names for inspiration.
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