There are three topics you shouldn’t discuss with friends: politics, religion … and spay/neuter.
Talking frankly about spaying and neutering is worth the backlash though … because of the health risks associated with it, especially in a young dog. One common problem is the link between spay/neuter and joint disease in dogs.
Unfortunately, many dog owners don’t know about the health risks of spay/neuter. Vets spend a lot of time telling you why you should spay or neuter your dog … but they spend very little time talking about why you shouldn’t. So … the goal of this article is to give you the information your vet doesn’t. Then you can make the best possible decision for your dog.
I’ll preface the article by stating that I breed Labrador Retrievers, a breed that can be prone to hip and elbow dysplasia, as well as cruciate tears. The families who get one of my puppies receive a warranty of sorts, saying that I have done everything I can to prevent these issues. 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.
But there is one disclaimer: 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 and joint disease are now shown to be related. Spay or neuter surgery can permanently change a healthy puppy joint into an unhealthy one.
Side Effects Of Spay/Neuter In Dogs
1. Abnormal Growth
At the heart of the matter is how spay/neuter affects your 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. One of their responsibilities is regulating growth.
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’re lighter in bone (1).
Studies have shown that when the sex hormones are removed, the growth hormones are missing important regulatory input …. so the bones continue to grow longer than they ought to.
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. As it builds bone, the bone becomes longer and the puppy gets larger and taller. Once the dog matures, this growth plate turns into bone and the puppy reaches his full height.
When dogs are sterilized before maturity, the closure of some but not all growth plates may be delayed (2). This is especially true if a dog is sterilized when only some of his growth plates are closed.
Elbow And Stifle Joints
The dog’s elbow and stifle joints have similar structures. Above each joint is one bone (the humerus and femur respectively), and below are two bones (in the elbow, the radius and ulna, and in the stifle the tibia and fibula). This means 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? Well … 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. This could in turn lead to increased risk of both elbow dysplasia and cranial cruciate ligament tears.
In 1993, researchers found that spayed and neutered dogs were twice as likely to suffer cranial cranial cruciate ligament rupture (3). Another study in 2004 also found increased risk in neutered dogs (4).
Chris Zinc DVM PhD DACVP explains (5) …
“… 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.”
Other researchers have found sterilization can cause a loss of bone mass, as well as obesity, especially in females (6). Both of these factors could lead to an increased risk of cranial cruciate ligament tears. Spayed or neutered dogs are more than three times more likely to suffer from patellar luxation (7).
2. Hip Dysplasia
The thought of hip dysplasia is enough to strike fear into any large breed dog lover. So the bulk of research on spay/neuter and joint disease has focused on this disorder.
Dogs who are sterilized before the age of six months have a 70% increased risk of developing hip dysplasia. Spain et al in a 2004 study propose that (8) …
“… 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 found that among a sample of dogs diagnosed with hip dysplasia, the dogs neutered six months prior to the diagnosis were nearly twice as likely to develop hip dysplasia (9).
Interestingly, a 1996 study by Dannuccia et al 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 (10).
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 (11).
In another study, male Rottweilers, a breed susceptible to osteosarcoma, were nearly 4 times more likely to develop osteosarcoma than intact dogs (12). In fact, Rottweilers spayed or neutered before one year of age had a 28.4% (males) and 25.1% (females) risk of developing osteosarcoma. The researchers concluded from their results that the longer the dogs were exposed to sex hormones, the lower their risk of osteosarcoma.
Other Spay/Neuter Risks
There are other related risks with spay/neuter, including:
- Increased risk of many cancers
- Urogenital disorders
- Cognitive impairment
Giving your dog any surgery and anesthesia poses additional risks for your dog. Keep these in mind as well when you decide if spay/neuter is an option for your dog.
One thing that is clear… is that the risk of joint disease in particular is greatly exaggerated if your 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. The real fallout from this imbalance 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 have been accepted as normal procedures for decades!
The age at which the growth plates close depends on your dog and 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.
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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’re spayed or neutered, especially before the age of two. After that age, it’s entirely up to the family whether they keep their dog intact or sterilize him.
I do an extremely thorough 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 often have a different view on spay/neuter and they are certainly entitled to it.
When considering if and when your dog should be spayed or neutered, it’s important that you make the decision based on facts. 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.
- Vasectomies and tubal ligations are also becoming more popular. They have the happy consequence of less interference with the sex hormones – and your dog gets to keep his or her reproductive organs right where nature intended them to be.
- There are zinc injections to sterilize male dogs (but these may be hard to find because of the company’s financial difficulties). This leaves about half of the circulating testosterone available to the body.
You have a choice about whether and when you spay or neuter your dog … and how important it is to you that his or 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 your dog can live with, happily and healthfully.
- RB Martin et al. Effects of ovariectomy in beagle dogs. Bone, Volume 8, Issue 1, 1987
- Salmeri KR, Bloomberg MS, Scruggs SL, Shille V. Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. J Am Vet Med Assoc. 1991 Apr 1;198(7):1193-203.
- Whitehair JG, Vasseur PB, Willits NH. Epidemiology of cranial cruciate ligament rupture in dogs. J Am Vet Med Assoc. 1993 Oct 1;203(7):1016-9.
- Slauterbeck JR, Pankratz K, Xu KT, Bozeman SC, Hardy DM. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res. 2004 Dec;(429):301-5.
- Chris Zink, DVM, PhD, DACVP, DACVSMR, CCRT, CVSMT, CVA. Spay-neuter considerations to maximize health. IVC Journal, February 6, 2017.
- Edney AT, Smith PM. Study of obesity in dogs visiting veterinary practices in the United Kingdom. Vet Rec. 1986 Apr 5;118(14):391-6.
- B. Vidoni, I. Sommerfeld-Stur, E. Eisenmenger. Diagnostic and genetic aspects of patellar luxation in small andminiature breed dogs in Austria. Wien.Tierarztl.Mschr.* (2005) 92, p170 – 181
- C. Victor Spain et al. Long term risks and benefits of early-age gonadectomy in dogs. Journal of the American Veterinary Medical Association, February 1, 2004, Vol. 224, No. 3 , Pages 380-387
- Marjan A. E. van Hagen, DVM et al. Incidence, risk factors, and heritability estimates of hind limb lameness caused by hip dysplasia in a birth cohort of Boxers. Am Journal of Veterinary Research. February 2005, Vol. 66, No. 2, Pages 307-312
- Dannucci GA, Martin RB, Patterson-Buckendahl P. Ovariectomy and trabecular bone remodeling in the dog. Calcif Tissue Int. 1987 Apr;40(4):194-9.
- Ru, G. et al. (1998). Host related risk factors for canine osteosarcoma. Vet J 156, 31-39.
- Cooley DM et al. Endogenous gonadal hormone exposure and bone sarcoma risk. Cancer Epidemiol Biomarkers Prev. 2002 Nov;11(11):1434-40.