SHOULD YOU NEUTER
Neutering health effects more severe for golden retrievers than Labradors July 14, 2014 Life & Non-humans Labrador retrievers are less vulnerable than golden retrievers to the long-term health effects of neutering, as evidenced by higher rates of certain joint disorders and devastating cancers, according to a new study by researchers at the University of California, Davis, School of Veterinary Medicine. Results of the study now appear online in the open-access journal PLOS ONE at http://tiny.cc/tia0ix. (This article was the first posted and is now below this article posted)
“We found in both breeds that neutering before the age of 6 months, which is common practice in the United States, significantly increased the occurrence of joint disorders – especially in the golden retrievers,” said lead investigator Benjamin Hart, a distinguished professor emeritus in the School of Veterinary Medicine. “The data, however, showed that the incidence rates of both joint disorders and cancers at various neuter ages were much more pronounced in golden retrievers than in the Labrador retrievers,” he said. He noted that the findings not only offer insights for researchers in both human and veterinary medicine, but are also important for breeders and dog owners contemplating when, and if, to neuter their 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.This new comparison of the two breeds was prompted by the research team’s earlier study, reported in February 2013, which found a marked increase in the incidence of two joint disorders and three cancers in golden retrievers that had been neutered. Health records of goldens and Labradors examined The golden retriever and the Labrador retriever were selected for this study because both are popular breeds that have been widely accepted as family pets and service dogs. The two breeds also are similar in body size, conformation and behavioral characteristics. The study was based on 13 years of health records from the UC Davis School of Veterinary Medicine for neutered and non-neutered male and female Labrador retrievers and golden retrievers between the ages of 1 and 8 years of age. These records included 1,015 golden retriever cases and 1,500 Labrador retriever cases. The researchers compared the two breeds according to the incidence of three cancers: lymphosarcoma, hemangiosarcoma and mast cell tumor. They also calculated the incidence for each breed of three joint disorders: hip dysplasia, cranial cruciate ligament tear and elbow dysplasia. The researchers also noted in these cases whether the dogs had been neutered before the age of 6 months, between 6 and 11 months, between 12 and 24 months or between age 2 and 9 years of age. Neutering and joint disorders. In terms of joint disorders, the researchers found that non-neutered males and females of both breeds experienced a five-percent rate of one or more joint disorders. Neutering before the age of 6 months was associated with a doubling of that rate to 10 percent in Labrador retrievers. In golden retrievers, however, the impact of neutering appeared to be much more severe. Neutering before the age of 6 months in goldens increased the incidence of joint disorders to what Hart called an “alarming” four-to-five times that of non-neutered dogs of the same breed. Male goldens experienced the greatest increase in joint disorders in the form of hip dysplasia and cranial cruciate ligament tear, while the increase for Labrador males occurred in the form of cranial cruciate ligament tear and elbow dysplasia. “The effects of neutering during the first year of a dog’s life, especially in larger breeds, undoubtedly reflects the vulnerability of their joints to the delayed closure of long-bone growth plates, when neutering removes the gonadal, or sex, hormones,” Hart said. Neutering and cancers The data also revealed important differences between the breeds in relation to the occurrence of cancers. In non-neutered dogs of both breeds, the incidence of one or more cancers ranged from 3 to 5 percent, except in male goldens, where cancer occurred at an 11-percent rate. Neutering appeared to have little effect on the cancer rate of male goldens. However, in female goldens, neutering at any point beyond 6 months elevated the risk of one or more cancers to three to four times the level of non-neutered females. Neutering in female Labradors increased the cancer incidence rate only slightly. “The striking effect of neutering in female golden retrievers, compared to male and female Labradors and male goldens, suggests that in female goldens the sex hormones have a protective effect against cancers throughout most of the dog’s life,” Hart said. Funding for the study was provided by the American Kennel Club Canine Health Foundation and the Center for Companion Animal Health at UC Davis.Read more at
This was the first article written I copied this from the website MOM
In contrast to European countries, the overwhelming majority of dogs in the U.S. are neutered (including spaying), usually done before one year of age. Given the importance of gonadal hormones in growth and development, this cultural contrast invites an analysis of the multiple organ systems that may be adversely affected by neutering. Using a single breed-specific dataset, the objective was to examine the variables of gender and age at the time of neutering versus leaving dogs gonadally intact, on all diseases occurring with sufficient frequency for statistical analyses. Given its popularity and vulnerability to various cancers and joint disorders, the Golden Retriever was chosen for this study. Veterinary hospital records of 759 client-owned, intact and neutered female and male dogs, 1–8 years old, were examined for diagnoses of hip dysplasia (HD), cranial cruciate ligament tear (CCL), lymphosarcoma (LSA), hemangiosarcoma (HSA), and mast cell tumor (MCT). Patients were classified as intact, or neutered early (<12 mo) or late (≥12 mo). Statistical analyses involved survival analyses and incidence rate comparisons. Outcomes at the 5 percent level of significance are reported. Of early-neutered males, 10 percent were diagnosed with HD, double the occurrence in intact males. There were no cases of CCL diagnosed in intact males or females, but in early-neutered males and females the occurrences were 5 percent and 8 percent, respectively. Almost 10 percent of early-neutered males were diagnosed with LSA, 3 times more than intact males. The percentage of HSA cases in late-neutered females (about 8 percent) was 4 times more than intact and early-neutered females. There were no cases of MCT in intact females, but the occurrence was nearly 6 percent in late-neutered females. The results have health implications for Golden Retriever companion and service dogs, and for oncologists using dogs as models of cancers that occur in humans.
The overwhelming majority of companion dogs maintained in the U.S. are spayed or castrated (both referred to herein as neutered) . Increasingly in the U.S. neutering is being performed early, demarcated in the present study as prior to one year of age. The impetus for this widespread practice is presumably pet population control, and is generally considered responsible pet ownership. However, this societal practice in the U.S. contrasts with the general attitudes in many European countries, where neutering is commonly avoided and not generally promoted by animal health authorities. For example, a study of 461 dogs in Sweden reported that 99 percent of the dogs were gonadally intact , and an intact rate of 57 percent was reported in a Hungarian study . In the United Kingdom, a 46 percent intact rate was reported .In the last decade, studies have pointed to some of the adverse effects of neutering in dogs on several health parameters by looking at one disease syndrome in one breed or in pooling data from several breeds. With regard to cancers, a study on osteosarcoma (OSA) in several breeds found a 2-fold increase in occurrence in neutered dogs relative to intact dogs . Another study on OSA, to explore the use of Rottweilers as a model for OSA in humans, found that neutering prior to 1 year of age was associated with an increased occurrence of OSA; 3–4 times that of intacts .Hemangiosarcoma is a cancer that is affected by neutering in females. A study of cardiac tumors in dogs found that cardiac HSA for spayed females was greater than 4 times that of intact females . A study on splenic HSA found the spayed females had more than 2 times the risk of developing this tumor as intact females . Neither of these studies separated early- versus late-spayed females with regard to increased risk, and neither focused on just one breed. A study on the epidemiology of LSA (lymphoma) in dogs, for comparison with human lymphoma, found that intact females had a significantly lower risk of developing this cancer than neutered females or neutered males or intact males . Another cancer of concern is prostate cancer, which occurs in neutered males about four times as frequently as in intact males . A study on cutaneous mast cell tumors (MCT) in several dog breeds, including the Golden Retriever, examined risk factors such as breed, size, and neuter status. Although early versus late neutering was not considered, the results showed a significant increase in frequency of MCT in neutered females; four times greater than that of intact females .In contrast to the rather strong evidence for neutering males and/or females as a risk factor for OSA, HSA, LSA, MCT, and prostate cancer, evidence for neutering as protection against a dog acquiring one or more cancers is weak. The most frequently mentioned is mammary cancer (MC) . However, a recent systematic review of published work on neutering and mammary tumors found the evidence that neutering reduces the risk of mammary neoplasia to be weak, at best .With regard to joint disorders affected by neutering, one study documents a 3-fold increase in excessive tibial plateau angle – a known risk factor for development of CCL – in large dogs . A paper on CCL found that, across all breeds, neutered males and females were 2 to 3 times more likely than intact dogs to have this disorder . In this study, with sexes combined, neutering significantly increased the likelihood of HD by 17 percent over that of intact dogs. Given the widespread practice of neutering in the U.S., especially with public campaigns promoting early neutering, and the contrast with neutering practices in other developed countries, the objective of this project was to retrospectively examine the effects of neutering on the risks of several diseases in the same breed, distinguishing between males and females and early or late neutering versus remaining intact using a single hospital database. Because neutering can be expected to disrupt the normal physiological developmental role of gonadal hormones on multiple organ systems, one can envision the occurrence of disease syndromes, including those listed below, to possibly be affected by neutering as a function of gender and the age at which neutering is performed. The study focused on the Golden Retriever, which is one of the most popular breeds in the U.S. and Europe. In this breed, HD, CCL, LSA, HSA, MCT, OSA, and elbow dysplasia (ED) are listed as being of particular concern .
No animal care and use committee approval was required because, in conformity with campus policy, the only data used were from retrospective veterinary hospital records. Upon approval, faculty from the University of California, Davis (UCD), School of Veterinary Medicine, are allowed restricted use of the record system for research purposes. The final dataset used for statistical analyses is available to qualified investigators, upon request, from the corresponding author.
The dataset used in this study was obtained from the computerized hospital record system (Veterinary Medical and Administrative Computer System) of the Veterinary Medical Teaching Hospital (VMTH) at UCD. The subjects included were gonadally intact and neutered female and male Golden Retrievers, 1 to 8 years of age and admitted to the hospital between January 1, 2000 and December 31, 2009. Data from patients less than 12 months of age and 9 years or older were not considered. Additional inclusion criteria were requirements for complete information on date of birth, date of neutering (if neutered) and date of diagnosis (or onset) of the joint disorder or cancer. Patients were classified as intact or neutered; the neutering was sub-classified as “early” if done before 12 months of age and “late” if done at 12 months of age or older. For all neutered patients, the neuter status at the time of each visit was reviewed to ensure that neutering occurred prior to onset of the first clinical signs or diagnosis of any disease of interest. While the study set out to estimate incidence rates related to age at the time of neutering, patients were diagnosed at different ages and with differing durations of the disease as well as varying years of exposure to the effects of gonadal hormone removal. For those intact, early-neutered and late-neutered dogs diagnosed with a disease, the age of diagnosis was recorded. Follow-up times were recorded for each patient and determined by age of the dog at the initial clinical signs or diagnosis, minus the age of the dog when first included in the study. For dogs with no disease, follow-up times were the age at the last visit to the VMTH minus the age when the dog was first included in the study. With the goal of obtaining a sample size sufficiently large for statistical analysis, the database records were initially screened using disease-related keywords to evaluate the frequency of occurrence of HD, CCL, HSA, LSA, MCT, ED, OSA, and MC. Extensive reviews of patient records were then performed for specific evidence and information on each joint disorder or cancer for every patient included in the study. Only diseases with at least 15 cases found using this screening were included in the study. For all patients where age at time of neutering was not available in the record, an effort was made to obtain the information by telephone from the referring veterinarian. At the same time, age of onset of the disease in question was also sought. If the information was not available from the referring veterinarian, an attempt was made to reach the dog owner for this information. In order to optimize success in obtaining information, these efforts were focused on patients born in 2000, or later, and that were admitted to the VMTH between January 1, 2005 and December 31, 2009. Table 1 defines the categories of diagnoses based on information in the record of each case. A patient was considered as having a disease of interest if the diagnosis was made at the VMTH or by a referring veterinarian and later confirmed at the VMTH. Patients clinically diagnosed with HD and/or CCL presented with clinical signs such as difficulty standing up, lameness, or joint pain; diagnosis was confirmed with radiographic evidence and/or orthopedic physical examination. Clinical diagnoses of the various cancers were accompanied by clinical signs such as enlarged lymph nodes, lumps on the skin or presence of masses, and confirmed by imaging, appropriate blood cell analyses, chemical panels, histopathology and cytology. When a diagnosis was suspected based on clinical signs, but the diagnostic tests were inconclusive or not done, telephone calls were made to referring veterinarians and owners to confirm the diagnosis. Lacking a conclusive confirmation, the case was excluded from the analysis for that specific joint disorder or cancer. Finally, body condition scores (BCS), ranging from 1 to 9 and obtained from the patient records (when available) were taken into account because BCS, as an indication of weight on the joints, is considered to play a role in the onset of these joint disorders , . Also, neutering has been implicated in an increase in body weight, especially as indicated by body condition score .
Citation: Torres de la Riva G, Hart BL, Farver TB, Oberbauer AM, Messam LLM, et al. (2013) Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. PLoS ONE 8(2): e55937. doi:10.1371/journal.pone.0055937
Editor: Bart O. Williams, Van Andel Institute, United States of America
Received: August 3, 2012; Accepted: January 4, 2013; Published: February 13, 2013
Copyright: © 2013 Torres de la Riva et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: Supported by the Canine Health Foundation (#01488-A) and the Center for Companion 330 Animal Health University of California, Davis (# 2009-54-F/M). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
They Studied Dogs That Had Extreme Longevity and Guess What They Found?
- A new study of German Shepherd Dogs adds to a growing body of research on the damaging effects of spaying and neutering on dogs
- Earlier studies on other breeds, including Rottweilers, Golden Retrievers, and Vizslas, suggest that desexing can dramatically increase the risk for serious diseases and behavioral disorders in these dogs
- When dealing with 100 percent responsible pet owners, my preference is to leave dogs intact whenever possible to avoid unnecessary risks of anesthesia. When pets must undergo a sterilization procedure, I advocate an alternative procedure to a full spay or neuter that spares the gonads and ovaries, which produce hormones essential to good health
- Ovary sparing spays are equally as effective as traditional spays at preventing unwanted litters, but they are less invasive and eliminate the risk of endocrine damage
- Veterinary schools need to teach less damaging sterilization methods to students, as research shows our current surgical approach to controlling unwanted pregnancies can permanently affect dogs in negative ways. In addition, the surgical technique used by high volume spay clinics and shelters to sterilize very young dogs could easily be updated to a less damaging technique, while still accomplishing the goal of preventing unwanted litters
By Dr. Becker
There is a growing body of evidence — including new research on German Shepherd Dogs (which I’ll discuss shortly) — that indicates spaying or neutering, in particular as it relates to large breed dogs desexed early in life, significantly increases the risk of serious health problems.
For Female Rottweilers, Ovary Removal Significantly Increases the Risk for a Major Fatal Disease
In 2009, a Gerald P. Murphy Cancer Foundation study found a correlation between the age at which female Rottweilers are spayed and their lifespan.1 The study compared female Rotties who lived to be 13 or older with a group who lived the expected lifespan of about 9 years.
According to lead researcher Dr. David J. Waters, a professor in the Department of Veterinary Clinical Sciences (VCS) at Purdue University:
“Like women, female dogs in our study had a distinct survival advantage over males. But taking away ovaries during the first [four] years of life completely erased the female survival advantage.
“We found that female Rottweilers that kept their ovaries for at least [six] years were [four] times more likely to reach exceptional longevity compared to females who had the shortest lifetime ovary exposure.”2
Because death from cancer is so prevalent in Rotties, researchers conducted a subgroup analysis of only dogs that did not die of cancer. This focused research further proved the strong association between intact ovaries and longevity.
Even in dogs that did not die of cancer, the females who kept their ovaries the longest were nine times more likely to achieve exceptional longevity (13+ years). Simply put, study results indicate removal of a Rottweiler’s ovaries significantly increases the risk for a major lethal disease.
Did You Know That in Europe, Intact Dogs Are the Norm?
A more recent study conducted at the University of California (UC), Davis provides additional evidence that spaying or neutering, and the age at which it is done, may increase a dog’s risk of certain cancers and joint diseases.
The U.S. takes a very different approach to spay/neuter compared to many European countries. In this country, not only are most dogs spayed or neutered, increasingly the preferred timing of the procedure is before the animal is a year old.
The motivation is for desexing is pet population control, and owners are considered responsible only if their pet has been sterilized. However, in many European countries, dogs remain intact and animal health experts do not promote spaying or neutering. The UC Davis study was undertaken, according to the researchers because:
“Given the importance of gonadal hormones in growth and development, this cultural contrast invites an analysis of the multiple organ systems that may be adversely affected by neutering.”3
In Desexed US Golden Retrievers, the Rates of Joint Disease and Cancer Are Much Higher Than in Intact Goldens
The researchers looked at the health records of 759 Golden Retrievers. Goldens were chosen because they are one of the most popular breeds in the U.S. and Europe, are often used as service dogs, and are also susceptible to various cancers and joint disorders.
The intent of the study was to investigate the effects of neutering on the risks of several diseases in a single breed of dog, distinguishing between males and females, and between dogs that had been neutered or spayed early (before one year), late (after one year), or not at all.
The dogs ranged in age from 1 to 8 years and had been seen at the UC Davis William R. Pritchard Veterinary Medical Teaching Hospital for one or more of the following problems:
- Hip dysplasia (HD)
- Cranial cruciate ligament (CCL) tear
- Lymphosarcoma (LSA)
- Hemangiosarcoma (HSA)
- Mast cell tumor (MCT)
The researchers focused on joint disorders and cancers because desexing removes the testes or ovaries and disrupts production of hormones that play an important role in body processes like bone growth plate closure.
Study results indicated that for all five diseases, the rates were significantly higher in both males and females that were neutered or spayed (before or after one year of age) compared with intact dogs.
Of special concern was that results showed a 100 percent increase in the rate of hip dysplasia in male Goldens neutered before 12 months of age.
Ten percent were diagnosed with the condition, which was double the rate of occurrence in intact males. Past studies have reported a 17 percent increase among all neutered dogs compared to all intact dogs.
The UC Davis researchers suggest that neutering male Golden Retrievers well beyond puberty will help prevent an increased risk of hip dysplasia, cranial cruciate ligament injury, and lymphosarcoma. For female Goldens, the research team concluded that:
“ … [T]he timing of neutering is more problematical because early neutering significantly increases the incidence rate of CCL from near [zero] to almost 8 percent, and late neutering increases the rates of HSA to 4 times that of the 1.6 percent rate for intact females and to 5.7 percent for, which was not diagnosed in intact females.” 4
Vizsla Study Suggests a Significantly Increased Risk for Cancer and Behavioral Disorders in Spayed or Neutered Dogs
A 2014 study of Vizslas included over 2,500 dogs and revealed that dogs neutered or spayed at any age were at significantly increased risk for developing mast cell cancer, lymphoma, all other cancers, all cancers combined, and fear of storms, compared with intact Vizslas.5
Dogs of both genders neutered or spayed at 6 months or younger had significantly increased odds of developing a behavioral disorder, including separation anxiety, noise phobia, timidity, excitability, submissive urination, aggression, hyperactivity, and/or fear biting.
When it came to thunderstorm phobia, all neutered or spayed Vizslas were at greater risk than intact Vizslas, regardless of age at neutering. The younger the age at neutering, the earlier the age at diagnosis with mast cell cancer, cancers other than mast cell, hemangiosarcoma, lymphoma, all cancers combined, a behavioral disorder, or fear of storms.
Spayed female Vizslas had a nine times higher incidence of hemangiosarcoma compared to intact females, regardless of when spaying was performed, however, no difference in incidence of this type of cancer was found for neutered vs. intact males. Neutered and spayed dogs had 4.3 times higher incidence of lymphoma, regardless of age at time of neutering, and a five times higher incidence of other types of cancer.
Spayed females had 6.5 times higher incidence of all cancers combined compared to intact females, and neutered males had 3.6 times higher incidence than intact males. The Vizsla researchers concluded:
“Additional studies are needed on the biological effects of removing gonadal hormones and on methods to render dogs infertile that do not involve gonadectomy.”6
German Shepherds Desexed Before 1 Year of Age Triple Their Risk of Joint Disorders
As I mentioned earlier, another very recent study was conducted at UC Davis, this time involving German Shepherds Dogs (GSDs). The study results suggest that spaying or neutering before 1 year of age triples the risk of joint disorders, in particular cranial cruciate ligament tears, in these dogs.7
The researchers analyzed the veterinary records of 1,170 GSDs, both neutered or spayed and intact, for a 14.5-year period. They looked for joint disorders and cancers already linked to desexing, and separated the dogs into categories that included intact, desexed before 6 months, between 6 and 11 months, and between 12 and 23 months.
The study found that 7 percent of intact males were diagnosed with one or more joint disorders compared with 21 percent of males neutered prior to 1 year of age. Five percent of intact females developed joint disorders, compared with 16 percent of females spayed before 1 year.
Intact female GSDs were found to develop mammary cancer at a rate of 4 percent, compared with less than 1 percent of females spayed before 1 year. Intact females had no diagnosed incidence of urinary incontinence, compared with 7 percent of females spayed before 1 year. According to lead researcher Dr. Benjamin Hart of the UC Davis School of Veterinary Medicine:
“Debilitating joint disorders of hip dysplasia, CCL and elbow dysplasia can shorten a dog’s useful working life and impact its role as a family member. Simply delaying the spay/neuter until the dog is a year old can markedly reduce the chance of a joint disorder.”8
My Preference Is to Sterilize, Not Desex
Since simply delaying a spay or neuter until a dog is older doesn’t address all the health challenges we see in desexed versus intact pets, I like the Vizsla researchers’ conclusion above that we need to investigate alternative methods of sterilizing dogs that do not involve removing the ovaries or testes.
As I explain in this video, over the years I’ve changed my view on spaying and neutering dogs, based not just on research studies, but also on the health challenges faced by so many of my canine patients after I spayed or neutered them. These were primarily irreversible metabolic diseases that appeared within a few years of a dog’s surgery.
These days I work with each individual pet owner to make decisions that will provide the most health benefits for the dog. Whenever possible, I prefer to leave dogs intact. However, this approach requires a highly responsible pet guardian who is fully committed to and capable of preventing the dog from mating (unless the owner is a responsible breeder and that’s the goal).
My clients are incredibly responsible and educated. I’ve never had a single unplanned pregnancy in my veterinary career. But I realize I’m not providing medical care to the entire world, and the world is full of irresponsible people.
My second choice is to sterilize without desexing. This means performing a procedure that will prevent pregnancy while sparing the testes or ovaries so they continue to produce hormones essential for the dog’s health. This can be done at any age, and could easily replace the current standard of desexing by high volume spay/neuter clinics and shelters around the country.
This typically involves a vasectomy for male dogs, and a modified spay for females. The modified spay removes the uterus while preserving the hormone-producing ovaries. This procedure is less invasive, requires shorter time under anesthesia, and yields the same results with no negative side effects.