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.
Hip Dysplasia
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.
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) …
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).
There are many things you can do to help your dog’s joints. Unfortunately … there are even more sinister issues with early neutering in dogs.
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.
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:
Another study in 2010 (10) found neutered dogs were more:
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.
24. Neilson JC, Eckstein RA, Hart BL. Effects of castration on the behavior of male dogs with reference to the role of age and experience. J Am Vet Med Assoc. (1997) 211:180–2.
Copyright © 2020 Hart, Hart, Thigpen and Willits. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Lacking a noticeable occurrence of increased joint disorders or cancers in neutered males or females, those wishing to neuter should decide on the appropriate age.
12. Hart BL, Hart LA, Thigpen AP, Willits NH. Long-term health effects of neutering dogs: comparison of labrador retrievers with golden retrievers. PLoS ONE. (2014). 9:e102241. doi: 10.1371/journal.pone.0102241
The study population was 198 intact males, 156 neutered males, 90 intact females, and 114 spayed females for a sample of 558 cases. The occurrence of joint disorders in intact males was 7 percent and 5 percent in intact females. Neutering at <6 mo. raised the incidence to 15 percent for males and to 18 percent for females, which did not reach significance for either. The cancers followed occurred at the 6 to 7 percent level in intact males and females. There were no significant increases above this with neutering males or females. The occurrence of MC in females left intact was 1 percent and 2 percent with spaying at 2–8 years. There was a 2 percent occurrence of PYO in intact females and no UI in early spayed females. Lacking a significant occurrence of increased joint disorders or cancers in neutered males or females, those wishing to neuter should decide on the appropriate age, but some people may wish to be cautious in view of the possible apparent risk in joint disorders.
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.
Dog Neuter Explained by a Vet | The reason to neuter and reasons not to neuter
Heavier mixed-breed dogs have higher health risks if neutered or spayed early, according to a new study from researchers at the University of California, Davis. The study found mixed-breed dogs weighing more than 44 pounds as adults are at higher risk for one or more joint disorders if neutered before 1 year of age. Dogs weighing up to 43 pounds had no increased risk for joint problems. The study was published in the journal Frontiers in Veterinary Science.
It’s standard practice in the U.S. and much of Europe to neuter dogs by 6 months of age. This study, which analyzed 15 years of data from thousands of dogs at UC Davis Veterinary Medical Teaching Hospital, suggests dog owners should consider their options carefully.
“Most dogs are mixed breeds,” said lead author Benjamin Hart, distinguished professor emeritus at the UC Davis School of Veterinary Medicine. “We hope this study will influence the spay or neuter process in order to give people wishing to adopt a puppy the time to make an informed decision on when to spay or neuter.”
Researchers examined common joint disorders including hip dysplasia, elbow dysplasia and cranial cruciate ligament tears, a knee injury, in five weight categories. They also looked at risks of mixed-breed dogs developing cancers based on weight but found no increased risk in any weight category compared to intact dogs.
The risk of joint disorders for heavier dogs can be up to a few times higher compared to dogs left intact. This was true for large mixed-breed dogs. For example, for female dogs over 43 pounds, the risk jumped from 4 percent for intact dogs to 10-12 percent if spayed before a year of age.
“The study raises unique challenges,” noted co-author Lynette Hart, professor at the UC Davis School of Veterinary Medicine. “People like to adopt puppies from shelters, but with mixed breeds it may be difficult to determine just how big the dog will become if you don’t know anything about the dog’s parents.”
Neutering prior to adoption is a common requirement or policy of humane societies, animal shelters and breeders. The authors suggested the policy be reviewed and modified appropriately. Shelters, breeders and humane societies should consider adopting a standard of neutering at over a year of age for dogs that will grow into large sizes.
“They need to take a serious look at this,” said Hart. “Joint disorders can shorten a dog’s useful working life and impact its role as a family member.”
A previous study conducted by the UC Davis researchers found health risks based on neuter age varied greatly depending on the breed of the dog.
Other authors include Abigail Thigpen with UC Davis School of Veterinary Medicine, and Neil Willits with the Department of Statistics in the UC Davis College of Letters and Science. Research support came from the Center of Companion Animal Health at UC Davis.