Breed-Specific Research
“It is earth shattering to consider that some of the cancers we have been battling may have been enhanced by early neutering instead of the reverse! ”
Golden Retriever Spay Neuter Research
Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers
A 2013 study involving 759 Golden Retrievers compared the incidence of hip dysplasia, cruciate ligament disease, and three different forms of cancer (lymphosarcoma, hemangiosarcoma, mast cell tumor) in dogs left intact, early-neutered dogs (those neutered before one year of age) and late-neutered dogs (those neutered after one year of age). There is an extremely high prevalence of lymphosarcoma in this breed. Significant findings were as follows:
Hip Dysplasia: The incidence of this disease was 5.1% in intact males, 10.3% in early-neutered males, and 3% in late-neutered males. No significant differences within the groups of female dogs were observed.
Cruciate ligament disease: Amongst all of the intact and late-neutered males and females, only one case was reported. The incidence of this disease was 5.1% in early-neutered females and 7.7% in early-neutered males.
Lymphosarcoma: The incidence of this disease was 9.6% in early-neutered males, 3.5% in intact males, and 0% in late-neutered males. No significant differences amongst the groups of female dogs were observed.
Hemangiosarcoma: The incidence of this disease was 1.8% in early-neutered females, 7.4% in late-neutered females, and 1.6% in intact females. No significant differences amongst the groups of male dogs were observed.
Mast cell tumor: The incidence of this disease was 2.3% in early-neutered females, 5.7% in late-neutered females, and 0% in intact females. No significant differences amongst the groups of male dogs were observed.
Conclusions
• The incidence of orthopedic diseases and various types of cancers in Golden Retrievers is significantly influenced by neutering.
• Age at the time of neutering is a significant factor in terms of disease incidence.
• Gender is a significant factor in terms of disease incidence.
• The higher incidence of orthopedic issues in neutered dogs may be related to alteration of the normal closure of bony growth plates which are responsible for elongation of bones. Closure of growth plates is normally triggered by the presence of reproductive hormones. Neutering before puberty delays growth plate closure.
Between 1989 and 2016, necropsy examinations were performed on 652 Golden Retrievers at the Center for Companion Animal Health, School of Veterinary Medicine, University of California, Davis. In 424 of the 652 dogs (65%), the cause of death was determined to be cancer. The median age at the time of death in cancer-related cases was 9.83 years. The median age of death caused by something other than cancer was 6.93 years.There was no significant difference in the proportion of intact males and castrated males dying of cancer, but a greater proportion of spayed females died of cancer compared to intact females. Intact females had shorter life spans than spayed females, and there was no difference in life expectancy between intact and castrated males. Ages of the dogs at the time of neutering were not taken into account.
Conclusions:
• Overall, Golden Retrievers have a substantial risk of cancer related death.
• While the risk for cancer increases with age.
• While reproductive status does not correlate with the incidence of cancer in male dogs, the incidence of cancer related death was higher in spayed females than intact females.
Labrador Spay Neuter Research
Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers
In 2014 a study was published comparing Labrador Retrievers and Golden Retrievers in terms of long-term health impacts of neutering. Included were 1,015 Golden Retrievers and 1,500 Labradors, all between 1 and 8 years of age. They were evaluated for orthopedic issues (hip dysplasia, cruciate ligament disease, elbow dysplasia) and multiple cancerous processes (lymphosarcoma, hemangiosarcoma, mast cell tumor, mammary cancer). Significant findings included the following:
Orthopedic diseases: The incidence of orthopedic issues was doubled in Labradors neutered before 6 months of age and was increased 4 to 5 fold in Golden Retrievers.
Cancers: Compared to Labrador Retrievers, neutering Golden Retrievers had an increased incidence of a variety of cancers in the female population and lymphosarcoma amongst the male dogs.
Conclusions
• Early neutering increases the incidence of joint disease. The higher incidence of orthopedic issues in neutered dogs may be related to alteration of the normal closure of bony growth plates which are responsible for normal elongation of bones. Closure of growth plates is normally triggered by the presence of reproductive hormones. Neutering before puberty delays growth plate closure.
• Spayed female Golden Retrievers and not Labradors have increased susceptibility to development of cancer.
• Early neutering increases the incidence of lymphosarcoma in Golden Retrievers, but not Labradors.
German Shepherd Spay Neuter Research
Neutering of German Shepherd Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence
A study of 1,170 German Shepherd Dogs was published in 2016. The objectives were to determine if neutering influences the incidence of orthopedic issues (hip dysplasia, cruciate ligament disease, elbow dysplasia) and various cancers (osteosarcoma, lymphosarcoma, hemangiosarcoma, mast cell tumor, mammary tumors). The impact of neutering on the incidence of urinary incontinence was also studied. Findings included:
Orthopedic Diseases: One or more orthopedic issues were diagnosed in 7% of intact males, 20.8% of males neutered before 1 year of age, and 16.4% of males neutered between 6 and 11 months of age. The most prevalent orthopedic issue amongst the neutered dogs was cruciate ligament disease, and amongst the intact dogs, hip dysplasia. One or more orthopedic issues were diagnosed in 5.1% of intact females, 12.5% of females neutered before 6 months of age, and 17% of females neutered between 6 and 11 months of age. As was the case with male dogs, cruciate ligament disease was the most common orthopedic issue within the neutered population and hip dysplasia was most common within the intact group.
Cancers: The incidence of mammary cancer (breast cancer) was 4.1% in intact females and 0% in females neutered before 6 months of age. In females neutered after 6 months of age, the incidence ranged up to 5%, depending on the age at the time of neutering. There were no other significant differences in the occurrence of cancer amongst the groups.
Urinary Incontinence: The incidence of urinary incontinence was 0% in intact females, 4.7% in females neutered before 6 months of age, and 7.3% in females neutered between 6 and 11 months of age.
Conclusions
• The incidence of joint disease, particularly cruciate ligament disease, is increased in neutered German Shepherds. The higher incidence of orthopedic issues in neutered dogs may be related to alteration of the normal closure of bony growth plates which are responsible for normal of bones. Closure of growth plates is normally triggered by the presence of reproductive hormones. Neutering before puberty delays growth plate closure.
• The incidence of mammary cancer is increased in intact German Shepherds (neutering before 6 months of age is protective).
• The incidence of urinary incontinence is increased in neutered female German Shepherds.
Rottweiler Spay Neuter Research
Published in 2002 and involving 683 Rottweilers, this study evaluated the relationship between the age at the time of spay/neuter and the development of osteosarcoma, a deadly form of bone cancer that is common within this breed. Significant findings included the following:
• Osteosarcoma was diagnosed in 12.6% of the dogs.
• Males and females neutered before 1 year of age had a 3-4 times greater incidence than intact dogs.
• The earlier neutering was performed, the greater the risk for osteosarcoma.
Exploring Mechanisms of Sex Differences in Longevity: Lifetime Ovary Exposure and Exceptional Longevity in Dogs
The second study compared the life expectancy of 183 Rottweilers based on the age at which they were neutered. Significant findings included the following:
• 83 of the dogs had exceptional longevity (reached 13 years of age or older).
• 100 dogs achieved an average life expectancy (average of 9.4 years).
• Intact females were more likely than intact males to have exceptional longevity. Spaying before 4 years of age eliminated this longevity advantage.
• Female dogs not spayed until 6-8 years of age were 3.2 times more likely to achieve exceptional longevity compared to those spayed at a younger age.
Conclusions
• Being intact is protective against the development of osteosarcoma.
• Unspayed females live longer than males. Early or mid-life spay abolishes this longevity advantage.
• Exceptional longevity is associated with the longest ovarian exposure.
Hungarian Vizsla Spay Neuter Research
Evaluation of the Risk and Age of Onset of Cancer and Behavioral Disorders in Gonadectomized Vizslas
A 2014 study documented the incidence of behavior issues and various types of cancer (mast cell cancer, hemangiosarcoma, lymphosarcoma) within a group of 2,505 Vizslas. The researchers documented the following:
Behavior issues: Dogs neutered before 6 months of age demonstrated a higher incidence of various behavior issues including: separation anxiety, fear of noises, timidity, aggression, and submissive urination. The younger the dog at the time of neutering, the earlier the age of onset of behavior issues.
Mast Cell Cancer: Neutered dogs (both males and females) had a 3.5 times higher incidence of this disease compared to their intact counterparts. This was true regardless of the age at the time of neutering.
Hemangiosarcoma: The incidence was significantly higher in the neutered females, regardless of the age at the time of neutering. The incidence was 9 times higher within the neutered male neutered after 12 months of age.
Lymphosarcoma: The incidence was 4.3 times higher in neutered dogs (both males and females) independent of age at the time of neutering.
Conclusions
• Neutered Vizslas have an increased incidence of various cancers.
• Neutering before 6 months of age increases the incidence of behavior issues.
• The earlier spay/neuter is performed, the earlier the recognition of cancer and behavior issues.
What About Other Large Dog Breeds?
We don't know if the data gleaned from Golden Retrievers, Labrador Retrievers, Rottweilers, Vizslas, and German Shepherds can be extrapolated to other large breed dogs. As shown above the ramifications of spay/neuter vary somewhat from breed to breed. What does appear to be consistent is the association of early neutering (before puberty) and the increased incidence of orthopedic issues.
What About Small Breed Dogs?
To date, there's been no data reported that is specific to smaller dog breeds. This website will be updated as more research results are generated.