Spay-Neuter Considerations for the Canine Athlete
One Veterinarian's Opinion
© 2005 Chris Zink DVM, PhD, DACVP
When the heat is on Lock it with PABS When your girl is in season use one of these to prevent an accidental breeding. PABS is an alternative to spaying. That your girl comes in season once or twice a year is not that much of an inconvenience if you have this belt. "You should consider your pet to be "in season" for 21 days: 7 days coming into heat, 7 days in heat, 7 days going out. Remember, although conception is most likely during the middle 14 days, Mother Nature doesn't always follow the rules."
We personnaly recommend the belt for 22 days to be safe.
WHY NOT SPAY IN THE FIRST 2 YEARS:
||Those of us with responsibility for the health of canine athletes need to continually read and evaluate new scientific studies to ensure that we are taking the most appropriate care of our performance dogs. This article provides evidence through a number of recent studies to suggest that veterinarians and owners working with canine athletes should revisit the standard protocol in which all dogs that are not intended for breeding are spayed and neutered at or before 6 months of age.
A study by Salmeri et al in 1991 found that bitches spayed at 7 weeks grew significantly taller than those spayed at 7 months, who were taller than those not spayed (or presumably spayed after the growth plates had closed).(1) A study of 1444 Golden Retrievers performed in 1998 and 1999 also found bitches and dogs spayed and neutered at less than a year of age weresignificantly taller than those spayed or neutered at more than a year of age.(2) The sex hormones, by communicating with a number of other growth-related hormones, promote the closure of the growth plates at puberty (3), so thebones of dogs or bitches neutered or spayed before puberty continue to grow. Dogs that have been spayed or neutered well before puberty can frequently be identified by their longer limbs, lighter bone structure, narrow chests and narrow skulls. This abnormal growth frequently results in significant alterations in body proportions and particularly the lengths (and therefore weights) of certain bones relative to others. 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. In addition, sex hormones are critical for achieving peak bone density.(4) These structural and physiological alterations may be the reason why at least one recent study showed that spayed and neutered dogs had a higher incidence of CCL rupture.(5) Another recent study showed that dogs spayed or neutered before 5 1/2 months had asignificantly higher incidence of hip dysplasia than those spayed or neutered after 5 1/2 months of age, although it should be noted that in this study there were no standard criteria for the diagnosis of hip dysplasia.(6) Nonetheless, breeders of purebred dogs should be cognizant of these studies and should consider whether or not pups they bred were spayed or neutered when considering breeding decisions.
A retrospective study of cardiac tumors in dogs showed that there was a 5 times greater risk ofhemangiosarcoma, one of the three most common cancers in dogs, in spayed bitches than intact bitches and a 2.4 times greater risk of hemangiosarcoma in neutered dogs as compared to intact males.(7) A study of 3218 dogs demonstrated that dogs that were neutered before a year of age had a significantly increased chance of developing bone cancer.(8) A separate study showed that neutered dogs had a two-fold higher risk of developing bone cancer.(9) Despite the common belief that neutering dogs helps prevent prostate cancer, at least one study suggests that neutering provides no benefit.(10) There certainly is evidence of a slightly increased risk of mammary cancer in female dogs after one heat cycle, and for increased risk with each subsequent heat. While about 30 % of mammary cancers are malignant, as in humans, when caught and surgically removed early the prognosis is very good.(12) Luckily, canine athletes are handled frequently and generally receive prompt veterinary care.
The study that identified a higher incidence of cranial cruciate ligament rupture in spayed or neutered dogs alsoidentified an increased incidence of sexual behaviors in males and females that were neutered early.(5) Further, the study that identified a higher incidence of hip dysplasia in dogs neutered or spayed before 5 1/2 months also showed that early age gonadectomy was associated with an increased incidence of noise phobias and undesirable sexual behaviors.(6) A recent report of the American Kennel Club Canine Health Foundation reported significantly more behavioral problems in spayed and neutered bitches and dogs. The most commonly observed behavioral problem in spayed females was fearful behavior and the most common problem in males was aggression.(12)
Other Health Considerations
A number of studies have shown that there is an increase in the incidence offemale urinary incontinence in dogs spayed early (13), although this finding has not been universal. Certainly there is evidence that ovarian hormones are critical for maintenance of genital tissue structure and contractility.(14, 15) Neutering also has been associated with an increased likelihood ofurethral sphincter incontinence in males.(16) This problem is an inconvenience, and not usually life-threatening, but nonetheless one that requires the dog to be medicated for life. A health survey of several thousand Golden Retrievers showed thatspayed or neutered dogs were more likely to develop hypothyroidism.(2) This study is consistent with the results of another study in which neutering and spaying was determined to be the most significant gender-associated risk factor for development of hypothyroidism.(17)Infectious diseases were more common in dogs that were spayed or neutered at 24 weeks or less as opposed to those undergoing gonadectomy at more than 24 weeks.(18) Finally, the AKC-CHF report demonstrated a higher incidence of adverse reactions to vaccines in neutered dogs as compared to intact.(12)
I have gathered these studies to show that our practice of routinely spaying or neutering every dog at or before the age of 6 months is not a black-and-white issue. Clearly more studies need to be done to evaluate the effects of prepubertal spaying and neutering, particularly in canines.
Currently, I have significant concerns with spaying or neutering pets before puberty. But of course, there is the pet overpopulation problem. How can we prevent the production of unwanted dogs while still leaving the gonads to produce the hormones that are so important to canine growth and development? One answer would be to perform vasectomies in males and tubal ligation in females, to be followed after maturity by ovariohysterectomy in females to prevent mammary cancer and pyometra. One possible disadvantage is that vasectomy does not prevent some unwanted behaviors associated with males such as marking and humping. On the other hand, females and neutered males frequently participate in these behaviors too. Really, training is the best solution for these issues. Another possible disadvantage is finding a veterinarian who is experienced in performing these procedures. Nonetheless, some do, and if the procedures were in greater demand, more veterinarians would learn them.
I believe it is important that we assess each situation individually. For canine athletes, I currently recommend that dogs and bitches be spayed after 14 months or neutered after 18 months of age.
This article is available for download in Adobe Acrobat PDF format Early Spay Considerations (PDF).
sorts, saying that I have done everything I can to prevent these
issues and if, despite my best efforts, the puppy I’ve bred ends up
with a debilitating joint issue, I will refund the purchase price to
the puppy’s family.
There is one disclaimer however
and it’s as follows: if the family decides to spay or neuter the
puppy before 24 months of age, my warranty is null and void. The
reason is that research shows I can’t guarantee the puppy’s
joints won’t be affected by this seemingly simple medical
procedure. Spay/neuter has the capability of permanently changing a
healthy puppy joint into an unhealthy one.
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
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
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
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
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.
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
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.
Getting back to my puppy
contract, given the above research, I simply can’t guarantee the
puppies I breed will have healthy joints if they are spayed or
neutered, especially before the age of two. Whether the puppy’s
family decides to keep their dog intact or sterilize him after that
age is entirely up to the family. I do an extremely good job of
screening the homes that apply for one of my puppies and if they
aren’t responsible enough to keep an intact animal, they certainly
aren’t responsible enough to deserve one of my precious puppies in
the first place.
People who are involved in
rescues and shelters may have a different view on this and they are
certainly entitled to it. When considering if and when your dog
should be spayed or neutered however, it’s important that you make
the decision based on facts and try to steer clear of an emotional
response that may affect the health and longevity of your dog. It’s
really not for me – or your vet – to dictate what you should do
with your dog.
Happily, there are alternatives
to the complete removal of the sexual organs. Vets are starting to
experiment with zinc injections to sterilize male dogs. This leaves
about half of the circulating testosterone available to the body.
Vasectomies and tubal ligations are also becoming more popular and
they have the happy consequence of less interference with the sex
hormones – and your dog gets to keep his reproductive organs right
where nature intended them to be.
You have a choice in whether
and when your dog is spayed or neutered and how important it is to
you that his/her sexual organs and hormones remain in place. Once
your dog is spayed or neutered, you can’t reverse your decision, so
dig a little deeper and you just might find a solution that you and
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2- Golden Retreiver Club of America Survey http://www.grca.org/healthsurvey.pdf http://www.grca.org/healthsurvey.pdf
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