1840: Health Implications of Early Spay/Neuter on Canine Health

Grant Status: Closed

Grant Amount: $146,589
Dr. Benjamin L Hart, DVM, PhD, University of California, Davis
February 1, 2014 - January 31, 2016
Sponsor(s): American German Shepherd Dog Charitable Foundation, Inc., Collie Health Foundation, Labrador Retriever Club, Inc., Portuguese Water Dog Foundation
Breed(s): -All Dogs
Research Program Area: Reproductive Conditions and Disease

Project Summary

The long-term goal of this project is to evaluate the breed-specific effects of neutering (both sexes) at different ages on joint disorders (hip dysplasia, cranial cruciate ligament tear and elbow dysplasia) and some cancers (lymphosarcoma, hemangiosarcoma, mast cell tumor). The effects of neutering at various ages were also examined in females with regard to mammary cancer, urinary incontinence and pyometra. The breeds examined were: Labrador Retrievers, German Shepherd Dogs, Dachshunds, Boxers, Rottweilers and Chihuahuas, Yorkshire Terriers, Shih Tzus, Corgis (two breeds combined for analyses), Doberman Pinschers and Bulldogs. In the space below, we will provide a summary of the findings.

Labrador Retriever (1,500 cases: males–272 neutered, 536 intact; females–347 neutered, 345 intact)
The findings on the Labrador Retriever are published. The major finding was a significant 2- fold increase in one or more joint disorders with neutering in the first year in both males and females above the 5 percent level of intact dogs. The occurrence of the cancers followed was low (3-4%) and not affected by neutering.

German Shepherd Dog (1,170 cases)
The paper is under review. Early neutering significantly increased the incidence of one or more joint disorders and the occurrence of the cancers followed was low and not affected by neutering.

Small-dog Breeds
Chihuahua (831 cases)
Yorkshire Terrier (553 cases)
Shih Tzu (322 cases)
 
These breeds lacked joint disorders associated with neutering at any age above the low incidence of intact dogs. The occurrence of one or more cancers was low in both intact and neutered dogs.

Long-dog breeds Dachshund (548 cases)
Corgis (191 cases)
Joint disorders in these breeds were not associated with neutering at any age above the low incidence of intact dogs. The occurrence of one or more cancers was low in both intact and neutered dogs. In male and female Dachshunds the occurrence of intervertebral disc disorders was high in intact dogs and not increased by neutering.

Rottweiler (696 cases)
Males and females showed an increase above intacts in one or more joint disorders with early neutering. The incidence of one or more of the cancers was not increased in either gender by neutering at any age.

Boxer (645 cases)
There was no increase in joint disorders associated with neutering at any age above the low incidence in intact dogs. Intact males had a fairly high incidence of cancers, which was increased in one of the neuter periods. Intact females had a fairly high incidence of cancers, not increased by neutering.

Doberman Pinscher (295 cases)
In males, there was no increase in one or more joint disorders associated with neutering above the low level in intact males. In females, however, there was an elevated incidence of joint disorders in an early neuter period, compared to none in intact females. In both sexes, the occurrence of cancers was less than the low level in intact dogs and not markedly affected by neutering.

Bulldog (471 cases)
The moderate occurrence of one or more joint disorders in intacts appeared not to be increased with neutering in males and females. For cancers, there was no evident increase in occurrence associated with neutering above the moderate level of intact male and female dogs.

Publication(s)

Hart, B. L., Hart, L. A., Thigpen, A. P., & Willits, N. H. (2016). Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence. Veterinary Medicine and Science, 2(3), 191–199. http://doi.org/10.1002/vms3.34

Hart, B.L., L.A. Hart, A.P. Thigpen and N. H. Willits. 2014. Long-term health effects of neutering dogs: Comparison of Labrador Retrievers and Golden Retrievers. PLoS ONE 9(7): 10.1371/journal.pone.0102241.

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