When it comes to spaying or neutering your dog, the timing of the procedure can significantly impact their long-term health. Traditionally, veterinarians have recommended spaying or neutering before six months of age. However, recent studies, including an update to the comprehensive studies by Drs. Benjamin and Lynette Hart from the University of California, Davis, have added to growing evidence that delaying these procedures can reduce the risk of cancer and joint disorders in certain breeds.
Why sex hormones are important for joint health
The timing of spaying and neutering is crucial because of the role that sex hormones play in a dog’s development. These hormones are involved in closing the growth plates in bones, which helps ensure proper joint formation. When a dog is spayed or neutered before reaching full maturity, the absence of these hormones can interfere with the growth plate closure, leading to an increased risk of joint disorders. This is particularly concerning for larger breeds, where the growth period is extended.
“The hormones are involved in setting the time when the growth plate of the leg bones close,” Lynette Hart, Ph.D. said in an American Kennel Club article about the findings. “If you’re neutering, then the growth of the leg bones is shifted just a little bit. The leg gets a little longer, and then it just doesn’t match well in the joint. That’s why you see an increase for some breeds in elbow dysplasia, hip dysplasia, or cranial cruciate tear.”
Updated guidelines for popular breeds
Previous studies on 35 popular dog breeds have shown that early spaying or neutering can increase the risk of joint disorders, like hip and elbow dysplasia, and certain cancers.
The latest research out of UC Davis, published in Frontiers in Veterinary Science, has expanded the guidelines for spaying and neutering to include five additional breeds: Siberian Husky, German Short/Wirehaired Pointer, Rhodesian Ridgeback, Newfoundland, and Mastiff. The study provides specific timelines for each breed to minimize the risk of joint disorders and certain types of cancer:
- German Short/Wirehaired Pointer: These popular hunting dogs showed a significant increase in joint disorders when neutered before six months. Female Pointers spayed early had a 38% chance of developing a joint disorder. Additionally, early neutering in males led to a higher risk of mast cell tumors (MCT) and hemangiosarcoma. The recommendation is to wait until at least 12 months before spaying or neutering to reduce these risks.
- Mastiff: Male Mastiffs neutered early had a higher risk of cranial cruciate ligament (CCL) tears and lymphosarcoma. While females also had an elevated risk of CCL tears, the increase was not statistically significant. The findings suggest delaying spaying or neutering Mastiffs to reduce these risks.
- Newfoundland: Female Newfoundlands spayed early showed a higher risk of joint disorders, while males neutered early had a non-significant increase. These results support the benefits of delayed spay and neuter, particularly for reducing joint disorders in this breed.
- Rhodesian Ridgeback: Early spaying in female Ridgebacks significantly increased the risk of MCT. Delaying spaying until after six months can help avoid this elevated risk.
- Siberian Husky: While the study found no significant effects on joint disorders or cancers, female Huskies had a non-significant but higher risk of CCL tears when spayed early. To err on the side of caution, delaying spaying until the dog is at least a year old is advisable.
These guidelines highlight the importance of considering breed-specific factors when deciding the timing of spaying or neutering. See a table of suggested spay/neuter age for 40 popular breeds, based on research by the Harts.
An alternative option: sterilize while preserving natural hormones
Natural sex hormones are important for lifelong health. In addition to increased joint disorders and cancers, spaying and neutering has been related to increased risk of obesity, incontinence, behavioral issues, diabetes, and hypothyroidism. Research has shown that the longer dogs have their natural sex hormones, the more likely they will live longer, healthier lives. Delaying spay and neuter can help, but are there other sterilization options to consider?
Hormone-sparing sterilization includes vasectomy for males and hysterectomy (also called ovary-sparing spay) for females. These procedures sterilize the dog without affecting natural hormones. It is important to note that dogs with sex hormones will behave like intact dogs after hormone-sparing sterilization. Visit our Hormone-Sparing Sterilization pages for an in-depth review of information on the impacts of spay and neuter on health and details on vasectomy and ovary-sparing spay procedures.
Making the right decision
The decision to sterilize a dog, and when and how to do so, is complex. It involves considering the dog’s breed, sex, health status, and lifestyle. While early spaying and neutering has been the norm, the growing body of evidence suggests that the benefits of natural hormones are significant, particularly for large breeds.
Veterinarians play a crucial role in guiding dog owners through this decision-making process. By discussing the risks and benefits of different options, they can help owners make informed choices that best suit their dogs’ needs.
See our directory of veterinarians who offer alternatives to traditional spay and neuter.
The Parsemus Foundation has been recognized by the Innovative Veterinary Care Journal for our efforts to raise awareness of the health benefits of delaying spaying and neutering and of hormone-sparing sterilization.
See our previous coverage of these topics.
