Wednesday, February 13, 2013

New Study: Neutering Affects Dog Health

"The study revealed that, for all five diseases analyzed, the disease rates were
significantly higher in both males and females that were neutered either early
or late compared with intact (non-neutered) dogs."

University of California, Davis

February 13, 2013


Neutering, and the age at which a dog is neutered, may affect the animal's risk

for developing certain cancers and joint diseases, according to a new study of

golden retrievers by a team of researchers at the University of California,


The study, which examined the health records of 759 golden retrievers, found a

surprising doubling of hip dysplasia among male dogs neutered before one year of

age. This and other results will be published today (Feb. 13) in the online

scientific journal PLOS ONE at

"The study results indicate that dog owners and service-dog trainers should

carefully consider when to have their male or female dogs neutered," said lead

investigator Benjamin Hart, a distinguished professor emeritus in the UC Davis

School of Veterinary Medicine.

"It is important to remember, however, that because different dog breeds have

different vulnerabilities to various diseases, the effects of early and late

neutering also may vary from breed to breed," he said.

While results of the new study are revealing, Hart said the relationship between

neutering and disease-risk remains a complex issue. For example, the increased

incidence of joint diseases among early-neutered dogs is likely a combination of

the effect of neutering on the young dog's growth plates as well as the increase

in weight on the joints that is commonly seen in neutered dogs.

Dog owners in the United States are overwhelmingly choosing to neuter their

dogs, in large part to prevent pet overpopulation or avoid unwanted behaviors.

In the U.S., surgical neutering -- known as spaying in females -- is usually

done when the dog is less than one year old.

In Europe, however, neutering is generally avoided by owners and trainers and

not promoted by animal health authorities, Hart said.

During the past decade, some studies have indicated that neutering can have

several adverse health effects for certain dog breeds. Those studies examined

individual diseases using data drawn from one breed or pooled from several


Against that backdrop, Hart and colleagues launched their study, using a single

hospital database. The study was designed to examine the effects of neutering on

the risks of several diseases in the same breed, distinguishing between males

and females and between early or late neutering and non-neutering.

The researchers chose to focus on the golden retriever because it is one of the

most popular breeds in the U.S. and Europe and is vulnerable to various cancers

and joint disorders. The breed also is favored for work as a service dog.

The research team reviewed the records of female and male golden retrievers,

ranging in age from 1 to 8 years, that had been examined at UC Davis' William R.

Pritchard Veterinary Medical Teaching Hospital for two joint disorders and three

cancers: hip dysplasia, cranial cruciate ligament tear, lymphosarcoma,

hemangiosarcoma and mast cell tumor. The dogs were classified as intact (not

neutered), neutered early (before 12 months age), or neutered late (at or after

12 months age).

Joint disorders and cancers are of particular interest because neutering removes

the male dog's testes and the female's ovaries, interrupting production of

certain hormones that play key roles in important body processes such as closure

of bone growth plates, and regulation of the estrous cycle in female dogs.

The study revealed that, for all five diseases analyzed, the disease rates were

significantly higher in both males and females that were neutered either early

or late compared with intact (non-neutered) dogs.

Specifically, early neutering was associated with an increase in the occurrence

of hip dysplasia, cranial cruciate ligament tear and lymphosarcoma in males and

of cranial cruciate ligament tear in females. Late neutering was associated with

the subsequent occurrence of mast cell tumors and hemangiosarcoma in females.

In most areas, the findings of this study were consistent with earlier studies,

suggesting similar increases in disease risks. The new study, however, was the

first to specifically report an increased risk of late neutering for mast cell

tumors and hemangiosarcoma.

Furthermore, the new study showed a surprising 100 percent increase, or

doubling, of the incidence of hip dysplasia among early-neutered males. Earlier

studies had reported a 17 percent increase among all neutered dogs compared to

all non-neutered dogs, indicating the importance of the new study in making

gender and age-of-neutering comparisons.

Other researchers on this UC Davis study were: Gretel Torres de la Riva, Thomas

Farver and Lynette Hart, School of Veterinary Medicine; Anita Oberbauer,

Department of Animal Science; Locksley Messam, Department of Public Health

Sciences; and Neil Willits, Department of Statistics.

About UC Davis

For more than 100 years, UC Davis has engaged in teaching, research and public

service that matter to California and transform the world.

Located close to the state capital, UC Davis has more than 33,000 students, more

than 2,500 faculty and more than 21,000 staff, an annual research budget of

nearly $750 million, a comprehensive health system and 13 specialized research

centers. The university offers interdisciplinary graduate study and more than

100 undergraduate majors in four colleges -- Agricultural and Environmental

Sciences, Biological Sciences, Engineering, and Letters and Science. It also

houses six professional schools -- Education, Law, Management, Medicine,

Veterinary Medicine and the Betty Irene Moore School of Nursing.

Media contact(s):

* Benjamin Hart, School of Veterinary Medicine, (530) 752-1555,

* Pat Bailey, UC Davis News Service, (530) 752-9843,

View this story on the Web at

Trina Wood, Communications Officer

UC Davis School of Veterinary Medicine

Office: 530-752-5257

UC Davis School of Veterinary Medicine -- Leading veterinary medicine,

addressing societal needs


  1. Note the effect of late neutering on female Goldens vs Hemangiosarcoma.

    A few years back, I went thru the Golden Retriever health database and compiled hemangio cases. Turns out most (IIRC about 85%) were in bitches 7 or 8 years old *that had been spayed within the previous six months*.

    I doubt the stats re any better on other breeds, but Goldens offer a very large sample, and are probably the most-often spayed and neutered
    of all breeds.

  2. Neutering not only affects dog health, it also affects cat health. There are quite a few articles on the adverse health effects of spaying and neutering dogs, but there are hardly any on the health risks of spaying and neutering cats.

    A few adverse effects have been noted, including an increase in risk of obesity, an increase in food intake, and an increase in shyness and hiding.

  3. A few more risks to spaying and neutering cats include an increased risk of diabetes and a risk for developing feline urological syndrome.

  4. A few other risks of neutering cats include a risk for feline lower urinary tract disease (FLUTD) and a decrease in metabolic rate. Neutered cats seem to be more prone to obesity than neutered dogs.

    There is even less information on the risks of spaying and neutering ferrets, but neutering ferrets, especially before sexual maturity, is a known risk factor for adrenal disease.

    Here are three articles that talk about adrenal disease in ferrets.
    1) Exotic Animal Care website's article on Adrenal Disease in ferrets:
    2) Doctors Foster and Smith website's article on Adrenal Disease in ferrets:
    3) Veterinary Partner website's article, What Ferret Owners Should Know About Adrenal Disease:

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  6. Oh great! So it's inexpensive to neuter your dog. Good thing you have health insurance because you will probably need it. Have you read any of the studies? There is a BIG reason NOT to get your dog neutered and that is HIS HEALTH AND LONGEVITY.
    The ONLY health indications for neutering are to treat testicular cancer or anal and prostate infetions that are refractory to other treatments. THAT'S IT. Neutering for any other reason is harmful to your dog, putting him at risk of a multitude of health problems including many cancers, hypothyroidism, orthopedic disorders like hip dysplasia and patellar luxation (that's bad knees for those without medical education). Search this blog under the "spay/neuter" label for the MANY posts we've done about the health problems associated with spay and neuter.
    Name me ONE health benefit from neutering, when done without a specific medical necessity. THERE IS NONE.

  7. Honestly, what is wrong with people? Can't anyone READ any more? I continually get ignorant comments spouted out from those who have obviously NOT read the post. I hesitate to approve such comments but will continue to try to educate people who may or may not have any reading comprehension skills.