The topic of neutering is emotionally charged for many pet owners.
It’s become the “responsible” thing to do. So we commonly hear of the benefits of this surgery … but rarely the risks.
And when savvy pet owners avoid early neutering (or forgo neutering altogether) to mitigate that risk … they’re often vilified for contributing to the pet over-population problem. But decisions made on emotion aren’t usually the best decisions we can make.
So here’s an objective and scientific look at what’s causing all the fuss. Let’s start with one well-known study that showed reasons to reconsider early neutering in dogs …
In February 2014, a study was completed on over 2500 Vizsla dogs and the results were a blow to those who vehemently defend spay/neuter (1). But this study is just the one of a long line of work showing that removing a quarter of the dog’s endocrine system might not be in the dog’s best interests – and maybe not even in the best interests of rescues and shelters.
Effects Of Neutering A Dog Too Early
Let’s look at what this research shows are the three most important reasons you should reconsider neutering your dog.
1. Early NeuterIng And Joint Disease
We’ll get to the Vizsla study later. They didn’t investigate the link between neuter and joint disease … but they didn’t really need to. There was already plenty of research showing the link.
A 2013 study on Golden Retrievers found that male dogs who were neutered before 12 months of age had double the risk of hip dysplasia than their intact counterparts (2). Other research shows that dogs sterilized before the age of six months have a 70% increased risk of developing hip dysplasia. The authors of this study 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’s even more evidence that neutering can increase the risk of hip dysplasia.
- In a 2005 study, Van Hagen et al found that of the sample dogs diagnosed with hip dysplasia, those who were neutered six months prior to the diagnosis were nearly twice as likely to develop hip dysplasia (3).
Cruciate Ligament Tears
Cranial cruciate ligament (CCL) tears have also been linked to neutering in numerous studies. The Golden Retriever study found that although there were no cases of cruciate tear in the intact dogs, 5% of males neutered before 12 months (and 8% of females) did suffer tears.
Whitehair et al (JAVMA Oct 1993), found that spayed and neutered dogs of any age were twice as likely to suffer cranial cruciate ligament rupture (4). In 2004, Slauterbeck et al also found an increased risk of cruciate tears (5).
Chris Zinc DVM PhD DACVP explains (6) …
“…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 obesity and a loss of bone mass (7). Both of these factors could lead to an increased risk of cranial cruciate ligament tear and hip dysplasia. And a 2005 Austrian study showed that spayed/neutered dogs are over three times more likely to suffer from patellar luxation (8).
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Unfortunately … there are even more sinister issues with early neutering in dogs.
2. Neutering And Cancer
Contrary to popular belief, we can’t neuter cancer. In fact, this surgery mostly increases the risk of many common canine cancers.
The Golden Retriever study found that the incidence of lymphosarcoma was three times higher in males neutered before 12 months of age. These results are similar to other studies. They also found that spayed/neutered dogs were 3.5% more likely to suffer mast cell cancer and 4.3 times more likely to suffer lymphoma.
2002 research on Rottweilers at Purdue University found that male and female dogs neutered or spayed before 1 year of age had an approximate one in four lifetime risk for bone sarcoma … and they were significantly more likely to develop bone sarcoma than dogs that were sexually intact (9).
A 2002 study at Utrecht University found that prostate cancer occurs in neutered males about four times as frequently as in intact males (10) … despite the popular belief that neutering prevents prostate cancer.
3. Neutering And Behavior
Neutering had been previously linked to cognitive impairment and even a three-fold risk of hypothyroidism (which often creates behavior changes). But the Viszla study yielded some particularly interesting insight into this link. They found that neutered dogs were also more likely to develop behavior disorders than intact dogs. The problems included:
- Fear of storms
- Separation anxiety
- Fear of noises
- Fear biting
Another study in 2010 (10) found neutered dogs were more:
- Less trainable than intact dogs
This is contrary to the popular belief that neutering reduces aggression and other behavior problems.
These findings also present a conundrum for shelters and rescues who advocate early neutering in dogs.
What Happens If You Neuter A Dog Too Early?
Reducing the number of dogs in shelters is an important goal … but it would be much better to prevent them from ending up at the shelter in the first place. Most people believe that shelters are full because of over-population. But in fact, behavior problems are the most common reason owners give up their dogs.
And is it fair for shelters to burden adopters with the increased risk of cancer and joint disease? There are alternatives to the complete removal of the reproductive organs and this might play a role in reducing the risk of cancer, joint disease and behavior issues.
Conventional neutering immediately shuts off the supply of protective hormones in the body. Hormones produced by the reproductive organs are essential for reproduction … but they’re also vital in developing …
- Body condition
- Cholesterol levels
- Energy levels
- Urinary continence
- Muscle tone
Reproductive hormones also play a role in the immune system. The rise in the risk of many cancers after removal of the reproductive organs is evidence of this.
Hopefully the emerging research will encourage more shelters to look into safer and less intrusive options.
Safer Neutering Options For Dogs
Modified neutering methods have less impact on the hormones and endocrine system. So dogs enjoy more hormone protection, even when sterilized.
Vasectomy can be a safer option for males. There is also a zinc injection but it may be hard to find due to the company’s recent financial difficulties.
Search this directory to find a veterinarian offering hormone-sparing neuter procedures.
Finally, if your goal is to give your dog the best chance at a life free of joint disease, cancer and behavior issues, then keeping your dog intact is certainly an option. If you’re thoughtful and caring enough to get this far in the article, you’re certainly thoughtful enough to manage an intact dog.
Simply make certain that your intact male isn’t allowed to wander (and you keep your intact female on leash for a few weeks when she is in estrus).
Removing a significant part of your dog’s endocrine system should be anything but routine.
As research continues to show the damning results of early neutering in dogs, it’s certainly in your dog’s best interests for you to consider these three important reasons to keep your best friend just the way mother nature made him.
- Zink, Christine M., et al. Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. Journal of the AVMA. 244(3):309-19
- De la Riva, Gretel, T., et al. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. Journal Pone. 0055937, Feb. 2013.
- Van Hagen, Jarjan A.E., et al. Incidence, risk factors, and heritability estimates of hind limb lameness caused by hip dysplasia in a birth cohort of Boxers. Journal AVMA. Feb. 2005, Vol. 66, No. 2
- Whitehair, J.G., et al. Epidemiology of cranial cruciate ligament rupture in dogs. Journal AVMA. 1993 Oct 1;203(7):1016-9.
- Slauterbeck, J.R., et al. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res. 2004 Dec;(429):301-5.
- Zink, Chris. Spay-neuter considerations to maximize health. Inn. Vet. Care Journal. Feb. 2017.
- RB Martin et al. Effects of ovariectomy in beagle dogs. Bone, Volume 8, Issue 1, 1987.
- Vidoni, B. Diagnostic and genetic aspects of patellar luxation in small and miniature breed dogs in Austria. Wiener Tierarztliche Monatsschrift. 92(8):170-181.
- Teske E, Naan EC, van Dijk E, Van Garderen E, Schalken JA (2002) Canine prostate carcinoma: epidemiological evidence of an increased risk in castrated dogs. Mol Cell Endocrinol 197: 251–255.
- Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters DJ. Endogenous gonadal hormone exposure and bone sarcoma risk. Cancer Epidemiol Biomarkers Prev. 2002 Nov;11(11):1434-40.
- Farhoody, Parvene, et al. Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs (Canis familiaris). Hunter College. May 2010.
- Spain, Victor C., et al. Long-term risks and benefits of early-age gonadectomy in dogs. Journal AVMA. Feb., 2004, Vol. 224, No. 3.
- Simpson, Melissa, et al. Age at gonadectomy and risk of overweight/obesity and orthopedic injury in a cohort of Golden Retrievers. Journal Pone. 0209131, 10.1371.