*Health Implications in Early Spay and Neuter in Dogs*
02/25/2013- AKC Canine Health Foundation
Recent results from research funded by the AKC Canine Health Foundation have the potential to significantly impact recommendations for spaying and neutering dogs in the United States. Most dogs in the United States are spayed or neutered, and for years the procedures have been completed prior to maturity. The study, published in the prominent, open access journal PLOS One, suggests that veterinarians should be more cautious about the age at which they spay and neuter in order to protect the overall health of dogs.
A team of researchers led by Dr. Benjamin L. Hart at the University of California, Davis has completed the most detailed study performed to date that evaluates incidence of cancer diagnoses and joint problems in one breed -- Golden Retrievers -- by neuter status: early (before 12 months old), late (12 months or older), and intact. Consistent with previous studies on the topic, the results showed increased likelihood of hemangiosarcoma, lymphoma, mast cell tumors, and canine cruciate ligament (CCL) rupture in neutered dogs.
The most profound observations were in hip dysplasia in male dogs when comparing early and late-neutering. The risk of development of hip dysplasia doubles, and disease occurs at a younger age in the early-neuter group compared to both the intact and late-neuter group. No occurrence of CCL disease was observed in intact male or intact female dogs, or in late-neutered females. In early-neutered dogs, the incidence of CCL was 5.1 percent in males and 7.7 percent in females, suggesting that neutering prior to sexual maturity significantly increases a dog’s risk of developing CCL disease. With respect to cancer, cases of lymphoma were 3-fold greater in the early-neutered males. Interestingly, incidence of mast cell tumors (male and female dogs) and hemangiosarcoma (female dogs only) were highest in the late-neuter group.
“Dr. Hart’s landmark study is the first to provide evidence for when to spay or neuter dogs. For years the veterinary community has been aware that early-spay and neuter may impact orthopedic health in dogs. Through a very detailed analysis and inclusion of body condition score as a risk factor, Dr. Hart was able to show that timing of spay and neuter does indeed have health implications,” said Dr. Shila Nordone, Chief Scientific Officer for the AKC Canine Health Foundation.
“CCL disease is painful, debilitating, and costs dog owners $1 billion annually to treat. The AKC Canine Health Foundation is committed to funding research, like Dr. Hart’s study, that can lead to evidence-based health recommendations. Armed with prudent guidelines for when to spay and neuter dogs we will have a significant impact on the quality of life for dogs,” continued Dr. Nordone.
Importantly, the task at hand is now to determine if the observations in this study are indeed true across all breeds and mixed breeds of dogs. Dr. Hart is interested in continuing his work by studying Labrador Retrievers, German Shepherd Dogs, and Dachshunds. Additionally, gaps in knowledge continue to exist concerning the complex relationship between sex hormones and cancer.
Last summer the AKC Canine Health Foundation released a podcast interview with Dr. Hart on his early-spay and neuter research as part of a series dedicated to the health of the canine athlete. To listen to the podcast visit www.akcchf.org/canineathlete
The publication “Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers” is available online through the open access journal PLOS One. The work was funded by the AKC Canine Health Foundation with sponsorship from the Golden Retriever Foundation, Schooley's Mountain Kennel Club, the Siberian Husky Club of America, and the Vizsla Club of America Welfare Foundation.
Take the time to listen to this podcast
01488-A: Health Implications of Spay and Neuter: Golden Retriever and Labrador Retriever
Grant Status: Closed
Grant Amount: $12,960
Dr. Benjamin L Hart, DVM, PhD, University of California, Davis
July 1, 2010 - June 30, 2011
Sponsor(s): Golden Retriever Foundation, Schooley's Mountain Kennel Club, Siberian Husky Club of America, Vizsla Club of America Welfare Foundation
Breed(s): Golden Retriever, Labrador Retriever
Disease(s): Hip Dysplasia
Studies in the last 10 years have pointed to broad adverse disease risks attributed to neutering. Yet, other work has profiled apparent increases in intact female dogs with mammary cancer and pyometra. Lacking specific information about disease risks, owners are left in the air as to how to use this information in decision making about spaying and neutering because the existing data-based studies have focused on just one breed and one disease, or combined all breeds together. Considering the differences among breeds in body size and the predisposition towards certain cancers or musculoskeletal disorders such as hip dysplasia and cranial cruciate ligament tears, one cannot currently weigh the relative advantages of proceeding with spay or neuter, and, if so, whether it should be conducted before or after puberty. The absence of data-based, breed-specific information about the possible adverse effects of spay/neuter (hereafter referred to as neuter) on several diseases of importance to a specific breed represents a gap in the information needed to allow caregivers to become active participants in decisions related to the long-term health of their dogs. In addition, given the strong attention that pet breeders give to breeding for a reduced tendency towards specific diseases that may plague a breed, one should know what diseases, if any, are affected by neutering for overall management of a disease important to the breed in question. This study focused on comparing the effects of neutering on increases or decreases in the risks of various diseases, primarily in the Golden Retriever and secondarily the Labrador Retriever. Disorders of the musculoskeletal system, particularly hip dysplasia, elbow dysplasia and cranial cruciate ligament tear were of major concern. Given the role of gonadal hormones in controlling the closure of bone growth plates, it should not be surprising that elimination of testosterone in males or estrogen in females through neutering may result in a significant increase in one or more musculoskeletal disorders. Cancers, including lymphoma, mast cell tumors, osteosarcoma, hemangiosarcoma and mammary cancer, were the next set of diseases examined. Lastly, urinary incontinence and pyometra were examined. The database for Golden Retrievers included 789 cases examined from the computerized hospital record system of the UC Davis, Veterinary Teaching Hospital, with case records going back 15 years prior to the start of the project. When the data were examined without regard to age at time of neutering, the incidence of most syndromes was low enough that even a 2- or 3-fold increase in the incidence of a disease syndrome between neutered and intact females or males did not reach significance. With 2,018 cases for Labrador Retrievers, analyses resulted in more frequent statistical significance, profiling an impact of neutering, particularly on musculoskeletal disorders. Hip dysplasia was significantly increased in both sexes and elbow dysplasia in males. The study involving a differentiation between neutering done at 1 year of age or sooner (early), and that done after 1 year (late), in Goldens was very telling. When all three musculoskeletal disorders were combined to determine the risk of an early neutered dog acquiring at least one of these disorders, there was a risk of about 25% in males and 20% in females, compared to a 5-6% risk in intact dogs. While still preliminary, these results are of serious importance to breeders and owners of Goldens. Of the cancers, lymphoma was significantly increased in both female and male dogs neutered at or before 1 year. Mammary cancer was very rare in both intact and neutered females, as was pyometra. This project lays out, more than any other study, the consequences of early neutering, and when completed, should provide useful information in managing the major decision as to when, and if, to neuter their puppy.
Source: AKC Canine Health Foundation