Spaying and neutering have long been considered standard veterinary care, primarily as a way to prevent unwanted litters and behaviors. Many families are familiar with the traditional approach, which involves the removal of the reproductive organs to achieve sterilization. While that method remains widely used and often appropriate, emerging research has prompted a more nuanced conversation around how these procedures may influence long-term health.
Conventional spay and neuter surgeries remove the ovaries in females and the testes in males. Along with preventing reproduction, removal of these organs also eliminates the body’s primary source of reproductive hormones such as estrogen and testosterone. But, those hormones are involved in far more than reproduction; they influence musculoskeletal development, immune function, metabolic balance, and behavior. When they are removed, especially early in life, the body adapts in ways that can shift normal physiology over time. In some dogs, this has been associated with an increased risk of orthopedic conditions, such as ligament injury or delayed joint maturation, as well as metabolic changes that may contribute to weight gain. Certain endocrine conditions, including hypothyroidism, are also observed more frequently in spayed and neutered populations. Behavioral patterns can shift as well, particularly in areas such as confidence, reactivity, or stress response. At the same time, preservation of natural hormone production may offer benefits that extend beyond reproduction alone. Reproductive hormones help maintain tissue integrity, support normal endocrine signaling, and contribute to overall vitality across the lifespan. Some evidence suggests that delaying spay or neuter until later in life may be associated with increased longevity in certain dog breeds or genetic lines, though results vary depending on breed and individual factors.
The timing of these procedures may also influence how the body adapts. Early removal of the gonads occurs before the endocrine system fully matures. In some cases, this may alter how other glands respond over time. The adrenal glands, for example, have the ability to produce small amounts of reproductive hormones. When the primary sources are removed, those glands may take on a greater share of that function. Some clinicians have proposed that this may contribute to atypical Cushing’s disease in a subset of patients, although research in this area is still developing. It is important to note that not every dog will experience these effects, and many do very well after traditional spay or neuter. Each option comes with its own considerations. Understanding how these procedures affect the body can help you choose what feels most appropriate for your dog.
Hormone-sparing sterilization offers an alternative approach that separates sterilization from hormone removal. In female dogs, the most common method is a hysterectomy, also called an ovary-sparing spay. During this procedure, the uterus and cervix are removed while the ovaries are left intact. Pregnancy is no longer possible, and the risk of uterine infection is eliminated when all uterine tissue has been fully removed. At the same time, the ovaries continue to produce hormones that allow the body to maintain more natural endocrine signaling, which, in turn, supports balanced development, stable metabolism, and more consistent communication between organ systems over time. Male dogs have a comparable option in vasectomy, where the vas deferens is interrupted without removing the testes. The dog is rendered sterile, yet hormone production remains unchanged.
Interest in these approaches has grown as more information becomes available about the long-term effects of removing reproductive hormones early in life. Some studies have reported associations between traditional spay and neuter and increased rates of certain conditions, including cancer, joint disorders, endocrine disease, and behavioral changes (Kutzler, 2020). Findings continue to evolve, and not every patient will experience these outcomes. Still, there is increasing recognition that sterilization methods are not interchangeable from a physiologic perspective.
An ovary-sparing spay does change what day-to-day life looks like with a female dog. Hormonal cycles still occur because the ovaries remain active. A dog will not be able to become pregnant, yet she may still be attractive to males during her cycle. Families who choose this approach often plan ahead for those periods by limiting exposure to intact males and adjusting their routines as needed.
Questions about cancer risk often arise when discussing the preservation of the ovaries. Ovarian cancer is considered uncommon in dogs. Mammary tumors are more frequently discussed, although available research presents mixed conclusions and includes limitations in study design. It is important to continue routine physical examinations, as many mammary tumors can be identified and addressed effectively when caught early. Mammary tumor risk may be higher in intact females, particularly depending on timing and individual factors. Hormonal cycles will continue, which may affect behavior, discharge, and attract male dogs during those periods. Tubal ligation is sometimes considered as another alternative, though it is not generally recommended in dogs. The uterus remains in place with that procedure, which allows for the possibility of pyometra, a serious and potentially life-threatening uterine infection, which also increases with age and can require emergency surgical intervention. Removal of the uterus during a hysterectomy avoids that concern. These procedures are not typically recommended for cats due to behavioral challenges associated with remaining intact.
Ultimately, each approach to sterilization carries its own balance of benefits and trade-offs. Traditional spay and neuter remain appropriate in many situations and continue to support population control. Hormone-sparing procedures preserve endocrine function and may reduce certain long-term risks, with additional considerations for care at home.
Thoughtful decision-making remains the most important part of the process. Breed, age, lifestyle, environment, and long-term goals all shape what is most appropriate for an individual patient. A personalized approach allows care to be guided by both current evidence and the specific needs of the animal in front of us. At Balanced Pet NW, care is centered on understanding the whole patient rather than applying a single standard to every case. When families are supported with clear information and a balanced perspective, they are better equipped to make decisions that support their animal’s long-term health and quality of life.
References
Kutzler, M. A. (2020). Possible relationship between long-term adverse health effects of gonadectomy and luteinizing hormone in dogs. Topics in Companion Animal Medicine, 39, 100469. https://doi.org/10.1016/j.tcam.2020.100469
