top of page

Early Spay and Neuter?????  DON'T!!!!!!

Gentle reader,

I have a confession to make.  Two actually: The first is I had my first dog in the 60s when the common
wisdom was to spay and neuter dogs early, generally at 6 months.  We were told this would prevent
bitches from having mammary cancer later on and we were assured our dog's disposition would  be
improved.  I honestly don't remember us ever having "disposition" issues....

We now know (peer reviewed, published research starting in the late 90s below), that this is bunk.  We
harm our dogs when they are s/n young. S/n does NOT improve disposition, there is no substitute for
training and socialization (she writes as three intact males sleep at her feet!).

The second confession is that I am frustrated. I stay on top of the latest medical research when it comes
to our furry companions and when I have a litter of puppies I do everything possible insure owners enjoy
them for a long and healthy, trouble free life. I (strongly!) counsel against early spay and neuter.
On occasion I might as well be talking to the walls. New owners take their precious puppy to the vet and,
depending on when the vet graduated vet school, (and heaven forbid there is a litter of unwanted
puppies), the owner is talked into spaying and neutering before the dog is sexually mature to the physical
and mental detriment of  their puppy/dog. Some vets aren't breeder friendly and will not accept clients

whose dogs aren't "fixed" (were they broken?") by a certain age.
This presents a problem for those who may want to show their dog in the breed ring, where a dog

under veterans' class must be intact, with finding friendly vet care.


Later, the same vet that counseled early spay/neuter is
generally the one who will blame health or orthopedic issues that might occur on genetics. There is no
denying genetics can throw a curve ball on occasion but here are some of the risks when you
spay or neuter your puppy before it is a sexually mature dog:

Abnormal growth, increased hip/elbow dysplasia and ACL (cruciate) tears

Increased incidences of cancer (hemangiosarcoma and lymphoma in GSDs),
diabetes, hyperthyroidism, chronic UTIs and incontinence in bitches

Loss of bone and muscle mass

Dogs are mentally immature, "puppy-like"; when s/n early a dog is usually "stuck" at the
maturity level of the time of s/n.  That's why you won't see service or working dog
organizations s/n early.

When to s/n a GSD?  Not before 18 months and closer to 24 months would be better still.
It's awkward when an owner receives conflicting information from their breeder and their veterinarian,
I understand that. I'm not asking anyone to take my word that early s/n is harmful ~ I have provided
peer reviewed, published research below with links to published articles, the latest from UC Davis funded by

a grant from the German Shepherd Dog Club of America and current links courtesy of the AKC.
The data is overwhelming.  Be your dog's advocate!
Please review the info below and share with your veterinarian.


Abnormal Growth

At the heart of the matter is how spay/neuter affects the dog’s hormones. When a dog’s reproductive
organs are surgically removed, the sex hormones they produce also disappear. The sex hormones
are responsible for more than just sexual behaviors and one of their responsibilities is regulating

Breeders can readily spot the difference between an intact dog and a neutered dog: neutered dogs
have longer limbs, narrower heads and bodies, and they are lighter in bone. When the sex hormones
are removed, the growth hormones are missing important regulatory input and the bones continue to
grow longer than they ought to. Studies have proven this to be true (Salmeri et al, JAVMA 1991).

In each long bone there is a growth (epiphyseal) plate, which is a band of cartilage found near the
joint. This growth plate lays down bone as a puppy develops and, as it builds bone, the bone
becomes longer and the puppy gets larger and taller. Once maturity is reached, this growth plate
turns into bone and the puppy’s full height is reached.

When dogs are sterilized before maturity, the closure of some but not all growth plates may be
delayed and this would be especially true if a dog is sterilized when only some of his growth plates
are closed.

The dog’s elbow and stifle joints are similarly designed. Above each joint is one bone (the humerus
and femur respectively), and below are two bones (in the elbow there is the radius and ulna and in the
stifle there is the tibia and fibula). One bone effectively sits on two. What would happen if one of those
bones underneath the joint stopped growing before the other bone and they ended up being different
lengths? It would be very much like building a house on a slope: the weight of the home wouldn’t be
evenly distributed and there would be increased load at the lowermost corner of the house.

The same could very well happen in the elbow and stifle joint when closure of the growth plates is
artificially delayed and this could in turn lead to increased risk of both elbow dysplasia and cranial
cruciate ligament tears.

There is research that supports this. Whitehair et al (JAVMA Oct 1993), found that spayed and
neutered dogs were twice as likely to suffer cranial cruciate ligament rupture. Slauterbeck et al also
found an increased risk (Clin Orthop Relat Res Dec 2004).

Chris Zinc DVM PhD DACVP explains, “…if the femur has achieved its genetically determined normal
length at eight months when a dog gets spayed or neutered, but the tibia, which normally stops
growing at 12 to 14 months of age continues to grow, then an abnormal angle may develop at the
stifle. In addition, with the extra growth, the lower leg below the stifle likely becomes heavier (because
it is longer), and may cause increased stresses on the cranial cruciate ligament.”

Additionally, sterilization can cause a loss of bone mass (Martin et al, Bone 1987), and obesity (Edney
et al, Vet Rec Apr 1986). Both of these factors could lead to an increased risk of cranial cruciate
ligament tear. Furthermore, spayed/neutered dogs are greater than three times more likely to suffer
from patellar luxation (Vidoni et al, Wien Tierartztl Mschr 2005).

Hip Dysplasia

The thought of hip dysplasia is enough to strike fear into any large breed dog lover. For that reason,
the bulk of research on spay/neuter and joint disease is focused on this disorder.

Dogs who are sterilized before the age of six months have a 70% increased risk of developing hip
dysplasia. The authors of this study (Spain et al, JAVMA 2004), propose that “it is possible that the
increase in bone length that results from early-age gonadectomy results in changes in joint
conformation, which could lead to a diagnosis of hip dysplasia.”

There is more evidence that spay/neuter can increase the risk of hip dysplasia. Van Hagen et al
(Am J Vet Res, Feb 2005), found that of the sample dogs diagnosed with hip dysplasia, those that were
neutered six months prior to the diagnosis were nearly twice as likely to develop hip dysplasia.

Interestingly, a study by Dannuccia et al (Calcif Tissue Int, 1986), found that removing the ovaries of
Beagles caused increased remodeling of the pelvic bone, which also suggests an increased risk of
hip dysplasia with sterilization.


Although not technically a joint issue, osteosarcoma is a cancer of the bone. This bears mentioning
because spayed and neutered dogs are twice as likely to develop this deadly disease (Ru et al, Vet J,
Jul 1998).

In another study, male Rottweilers, a breed susceptible to osteosarcoma, were nearly four times more
likely to develop osteosarcoma than intact dogs (Cooley et al, Cancer Epidemiol Biomarkers Prev,
Nov 2002). In fact, Rottweilers spayed or neutered before one year of age had a 28.4%(males) and
25.1% (females) risk of developing osteosarcoma. Interestingly, the researchers concluded from their
results that the longer the dogs were exposed to sex hormones, the lower their risk of osteosarcoma.

Playing Roulette

There are other related risks with spay/neuter, including an increased risk of many cancers,
hypothyroidism, diabetes, urogenital disorders, cognitive impairment, obesity and adverse vaccine
reactions – not to mention the risk associated with the surgery and the anesthetic. These risks should
all be considered when it comes time to decide if spay/neuter is an option for your dog.

What does seem to be clear is that the risk of joint disease in particular is greatly exaggerated if the
dog is sterilized before the growth plates close. It’s important to remember that the sex hormones do
play a synergistic role in your dog’s growth and development and their removal will create imbalance
in the body. Just what the fallout from this imbalance entails remains to be seen, as research into the
effects of sterilization is in its infancy, even though hysterectomies on humans and spay/neuter on
dogs has been accepted as a normal procedure for decades!

The age at which the growth plates close is entirely dependent on the dog and the breed. In general,
the larger the dog, the later the growth plates will close. In giant breeds, this could be nearly two years
of age.

Credit to Dana Scott, Editor In Chief for Dogs Naturally Magazine


On neutering, you will be hard pressed to find a vet today that would recommend anything but neutering
your pet early in their life, normally around six months. The reasons given are always the same, prevent
unwanted babies and long term health benefits including a reduction in cancer.

But unlike your appendix for example where it's absence is not noticed in your daily routine, your
reproductive (or sex) organs play a whole host of hormonal roles that stretch far beyond the
manufacturing of babies. Like food, parasite control, annual boosting and casual steroid shots,
these things are not without consequence for the patient and too rarely are these consequences ever
discussed with the owner. It is not enough that we are told things are perfectly harmless. We must go
into the decision with eyes wide open.

So here's what we know of neutering dogs early in their life. The implications for your pet and society as
a whole are then discussed below. It's a whopper of an article, maybe grab a cup of tea first! This would
normally be two articles but if I chop it in half people will be left with too many questions. Please leave
emotion at the door.

In male mammals the gonads are the two testes, and in females the gonads are the two ovaries.

The gonads are best known for making gametes (single celled germ cells) which is sperm in males and
eggs in females. These two cells then get it on inside the female and make a baby. Most of us have that
down pat.

But the gonads also produce a variety of hormones including the female sex hormones estrogen and
progesterone; and the male hormones including testosterone and androsterone. However men
necessarily have some of the female hormones, and women some of the male hormones.

While sex hormones in males and females function largely in the whole “sex” business from conception
to baby birth, they also play pivotal roles in the maintenance of body muscle and bone growth.

We see testosterone's dramatic effects in lanky 13 year old males. It controls all the typical puberty bits
in males such as the less useful growth of the adams apple, facial and body hair to the very much more
useful height and muscle mass of the individual. As adults testosterone continues to function in
maintaining muscle strength and mass, and it promotes healthy bone density. It also reduces body fat
(one reason why some spayed pets can put on weight).

Estrogen too functions in skeletal growth. At puberty, estrogen promotes skeletal maturation and the
gradual, progressive closure of the epiphyseal growth plate (plates of cartilage at the end of bones,
which are responsible for laying down new bone). Estrogen also functions in maintaining the mineral
acquisition by your bones.

Neutering or 'spaying' a female animal involves removing the womb and ovaries (an ovaro-
hysterectomy). Males are castrated whereby the testicles are surgically removed. This is done before
dogs come into puberty (i.e. start producing sex hormones for the first time) which is very approximately
6 months in males and around 9 months in females, though breed and body size play large rolls here.
General advice from the majority of veterinary circles is that responsible dog owners neuter at 6m
months. In other countries it is much earlier. Both operations are carried out under general anesthetic.

The number one reason for removing the sex hormones is to prevent unwanted breeding, hence folk at
the front line of mopping up all our unwanted fur babies are very big fans. The major health benefit
constantly cited is to prevent the possible occurrence of testicular cancer, peri-anal cancers and
ovarian cancers in dogs and cats. Other reasons often cited is the spread of inferior genetic traits and
to reduce problematic behaviour including male-male aggression around females in heat and the
roaming behaviour of both males and females when love is in the air.

The early neutering of dogs is not without it's side effects or critics, and I'm certainly one of them. But
please, before the heavily stressed and over-worked shelter staff post up about overpopulation
problems (I spent a couple of years in them too), lets look at this issue with less emotion and more

If we ignore the fact that gonadal cancers are rare enough in a general population and that dogs
recover very well from testicular cancer following diagnosis and castration, by removing the gonads in
developing animals you certainly prevent the possible occurrence of gonadal cancers such as testicular
and ovarian cancer. However, ironically, while these possible cancers of your pet will be avoided,
numerous studies show that removing the sex organs early in the developmental period of an animal
causes cancer in your pet, just not in their testes or ovaries.

A study in the Journal of Veterinary Internal Medicine, compiled over 13 years found that "… neutering
dogs appeared to increase the risk of cardiac tumor in both sexes”. The results showed that spayed
females were five times more likely to to suffer tumours of the heart than intact females
(Ware and Hopper, 1999,

In another study spanning 14 years of research it was concluded that sterlisation increased the risk for
bone cancer in large breed pure-breds twofold.
(Ru et al. 1998,

Upon further investigation using male and female Rottweilers spayed or neutered before one year of
age, both sexes were found to be significantly more likely to develop bone cancer than intact dogs with
early sterlisation bestowing a staggering 25% likelihood of bone cancer in your Rottweiler.
(Cooley et al. 2002,

It's often stated that neutering a male dog will prevent prostate cancer but some authors refute this on
the basis that “ non-testicular androgens exert a significant influence on the canine prostate”. The
College of Veterinary Medicine at Michigan State University found "…castration at any age showed no
sparing effect on the risk of development of prostate cancer in the dog."

All these considered, it's hard to argue the cancer benefits to neutering early or you end up playing the
whole “I see your very slight chance of testicular cancer and raise you a certain increase in bone and
heart tumours”.

Testosterone and estrogen play pivotal roles in the development of your muscles and bones. It stands
to reason that if you remove testosterone and estrogen from the vital and dramatic puberty growth
phase there will be consequences to that individual's height, muscle mass and bone formation of the
individual, compared to an intact animal of the same size and breeding. Studies show this to be
absolutely the case.

A study by Stubbs and Bloomberg (1995) set out to answer the following theory: Estrogen tells the
growth plates to stop. Thus if you remove the estrogen-producing organs in immature dogs, female and
male, you could expect cause growth plates to remain open and the dog to grow longer bones. They
divided dogs and cats into three groups. Group one was neutered at 7 wks, group two at 7 months, and
group three remained unneutered. They found that “early spay/neuter may result in a slight increase in
adult height”. The earlier the spay the taller the dog. Other authors found similar findings (Salmeri et al
Preston Stubbs, DVM & Mark Bloomberg, DVM Seminars in Vet Med & Surgery, Small Animal, Volume
10, No 1 Feb 1995 Dept of Small Animal Clin Sci, Univ of Florida
Katherine Salmeri, DVM, Mark Bllomber, DVM, Sherry Scuggs, BS, Victor Shille DVM, Journal of
American Vet Med Association, Volume 198, No 7 1991

Thus with no estrogen to shut it down, these animals can continue to grow and wind up with abnormal
growth patterns and bone structure. This results in irregular body proportions.

Grumbach (2000) quotes Chris Zink, DVM to explain the problem with neutering males and females
early and cruciate rupture - "For example, if the femur has achieved its genetically determined normal
length at 8 months when a dog gets spayed or neutered, but the tibia, which normally stops growing at
12 to 14 months of age continues to grow, then an abnormal angle may develop at the stifle. In addition,
with the extra growth, the lower leg below the stifle likely becomes heavier (because it is longer), and
may cause increased stresses on the cranial cruciate ligament."

This is verified with a study by Slauterbeck et al. (2004) who found that spayed and neutered dogs had
a significantly higher incidence of ACL rupture than their intact counterparts, regardless of breed or size.

A study by the Cornell University's College of Veterinary Medicine and published in the Journal of the
American Veterinary Medical Association showed that both male and female dogs sterilized at an early
age were more prone to hip dysplasia.

When one organ is removed, others will suffer and spayed and neutered Golden Retrievers are proven
to be more likely to develop hypothyroidism.
Panciera DL. Hypothyroidism in dogs: 66 cases (1987-1992). J Am Vet Med Assoc. 1994 Mar 1;204(5):
Glickman L, N Glickman, and R Thorpe. The Golden Retriever Club of America National Health Survey,
1998-1999. Available online at

Early neutering increases the risk of urinary incontinence by 4-20%

Very early neutering increases the risk of disease in dogs. A study of shelter dogs conducted by the
College of Veterinary Medicine at Texas A&M University concluded that infectious diseases were more
common in dogs that were sterilized at less than 24 weeks of age.

Dr. Karen Becker is now a famous veterinary advocate for more thought to be brought back in to the
dog world. Her youtube video last year on neutering and article on same subject gave me the bones of
this article. The video received an enormous amount of support but also scathing criticism. Since then
Dr. Becker has released another video on the subject explaining her thoughts on the whole affair. She
breaks down in the middle of it when she thinks about the number of animals she has harmed with her
previous advice. Worth a watch.

To quote Dr. Becker:

“As responsible members of society, we owe it to our communities to proactively protect our intact pets
from unplanned breeding at all costs. We must hold ourselves to the highest standard of reproductive
control over the intact animals we are responsible for.

Clearly, there are health benefits to be derived from waiting until after puberty to spay or neuter your
dog. However, there are also significant risks associated with owning an intact, maturing pet.

How seriously you take your responsibility as a pet owner is the biggest determining factor in how risky it
is to leave your dog intact until he or she matures. If you are responsible enough to absolutely
guarantee your unsterilized pet will not have the opportunity to mate, I would encourage you to wait until
your pet is past puberty to spay or neuter.

If you are unable to absolutely guarantee you can prevent your dog from mating and adding to the
shameful, tragic problem of pet overpopulation, then I strongly encourage you to get your animal
sterilized as soon as it's safe to do so”.

It is interesting to note that some vet organisations agree with Dr. Becker. While the American
Veterinary Association pushes for early neutering there are some European Veterinary Associations
that defend the view that “when reproduction is not an issue, then neutering, particularly of dogs, should
be decided on a case-by-case basis...”

In my opinion it is quite clear that neutering your dog early, before he / she is a fully formed, mature
adult, comes with very significant health concerns. The best advice from a health perspective would be
to put off neutering your pet until after puberty, which is at least a year, though some large breeds are
still maturing at two years of age. And for all these major health benefits in your dog, all it takes is a little
responsible pet ownership during the 3 – 6 month danger time.

Thank you to “Dog’s First” for the above.

Health Implications of Early Spay/Neuter on Canine Health

Principal Investigator: Dr. Benjamin L. Hart, DVM, PhD
Research Institution: University of California, Davis
Grant Amount: $146,589
Grant Start/End Date: February 1, 2014 – January 31, 2016
Progress Report: End-Year 1
Report Received: January 31, 2015

Grant Objectives: To develop a generalized understanding of the impact of early spay and
neuter on disease risk in dogs.

Report to Grant Sponsor from Investigator:  Adverse Long-term Health Effects of Neutering in
Different Breeds of Dogs


The long-term goal of this project is to evaluate, using one consistent and uniform data base at our
large veterinary medical center, the breed-specific effects of neutering at different ages on joint
disorders (hip dysplasia, cranial cruciate ligament tear and elbow dysplasia) and some cancers
(lymphosarcoma, hemangiosarcoma, mast cell tumor) that can be increased by neutering. The effects of neutering at various ages are also examined with regard to mammary cancer, urinary incontinence, and pyometra in females.

The research over the past year covers the popular German Shepherd Dog, the most important military and police canine.

German Shepherd Dog
We found that 7% of intact males and 5% of intact females were diagnosed with one or more joint
disorders. But neutering in either sex at less than 6 months, or between 6 months and 11 months,
increased the incidence of one or more joint disorders by 3-fold over that of the intact dogs, resulting in as high as 22% of dogs having a joint disorder. The occurrence of the cancers we followed in this breed was especially low in the intact males and females – 3% or less – and was not affected in either sex by neutering. Urinary incontinence, a very inconvenient problem in some females, did not occur in any intact females, but got as high as 7% in females neutered in the first year.

German Shepherd, Bottom Line
Delaying neutering and spaying (if done) in German Shepherd Dogs until they are at least 1 year old markedly reduces the likelihood of one or more disabling joint disorders. Delaying spaying of females beyond 1 year also reduces the chance of urinary incontinence, while not increasing the chance of mammary cancer.

Latest update 5/2016, copy and paste the following link in your browser:

Funded, German Shepherd Dog Club Of America Charitable Foundation


They say a picture is worth 1000 words.  Please see below for
the average time for growth plate closure and you will visualize
why there can be incongruity in joints (causing joint disease)
when dogs are spayed and neutered early. Please note that the
larger the dog, the longer it takes for growth plates to close.  A
toy dog matures more quickly than a medium or giant breed.

bottom of page