This has been an interesting thread to follow. There has been some good information and perspective shared here but I feel the need to jump in to correct some misinformation and add a few more thoughts for consideration.
First, what we "know" and "don't know" about the health benefit/detriment analysis regarding S/N. Far too much generalization and extrapolation is happening than is warranted by the evidence.
For example, the following statements from this thread are demonstrably untrue, exaggerated or not supported by any published data:
"Early spay/neuter leads to elongated and weaker bones."
A few limited studies in purebred dog breeds (mostly Golden Retriever and Labrador Retriever), with small sample sizes have demonstrated a potential correlation between S/N and CCL injury. A couple of other studies have found a correlation between S/N and hip dysplasia in GSD. Other studies (some conducted in European countries where dogs are less likely to be S/N) have already called those correlations into question...finding that breed, body weight and conformation are bigger risk factors than S/N status. Importantly, there are no studies in large, representative (including mixed breeds) populations of dogs evaluated by primary care veterinarians (rather than specialty or referral clinics which are likely to be a skewed population). We should be asking researchers why they continue to refuse to conduct research on those representative populations or account for those confounding variables. Could it be that, if they do, the S/N correlation will no longer be significant? Also, there are zero studies with significant sample sizes or good quality data correlating S/N with ANY OTHER ORTHOPEDIC CONDITION (developmental orthopedic disease, "arthritis", IVDD, chondrodysplasia, etc.).
"...Research in general shows that female dogs are likely to have incontinence issues after spay regardless of age, its just a slightly higher % for pediatric. "
While it does appear that urinary incontinence may be correlated with S/N, it is hardly a "common" condition (across many studies, the average incidence appears to be around 5%), it is unclear if age at S/N plays a role, and some studies (in European countries) have found specifics breeds to be a bigger risk factor than being spayed.
" The advantages of hormone sparing are stronger bones and joints, lower cancer risk, Fewer if any UTI's and better metabolic health."
See notes above about orthopedic conditions. There is a "lower cancer risk" for a few, specific, relatively rare cancers like hemangiosarcoma, osteosarcoma, etc. (except in breeds known to be at elevated risk) in intact dogs. Many studies have found breed increases risk for these cancers much more than S/N. There is a higher risk for other cancers in intact dogs (some of which are much more common) such as mammary carcinoma, prostate cancer, testicular cancer, mast cell tumors, etc. Risk for many of those cancers is not generally associated with breed or other factors, but almost exclusively with retention of gonadal hormones. Urinary tract infections (along with juvenile/recessed vulva) are not more common in S/N dogs...conclusively demonstrated in multiple studies. Metabolic and inflammatory diseases have also been studied and risk for them has not been associated with S/N status. Risk for "obesity" (which could be considered a metabolic condition) is higher in S/N dogs but is offset by adjustments to caloric intake and exercise.
So, what do we "know"...studies (across decades, countries and representative populations of dogs) have concluded that >20% of intact female dogs will develop pyometra, ~13% of intact female dogs will develop mammary carcinoma, >80% of intact male dogs will develop prostatic hyperplasia (a much more serious problem than most folks realize, esp. If their dogs have always been neutered). There are a number of other health conditions strongly associated with retention of gonads. We also know, based on multiple studies of large representative populations (some with more than a million dogs included) from multiple countries, that S/N dogs live longer (which also, incidentally, raises the risk for all cancers; longer lifespan=more cancer).
Behavioral impacts of S/N are unclear/equivocal/inconsistent, there is no validated, standardized assessment instrument and the current studies are often based on unreliable behavioral assessments by owners (we all know how good owners are at assessing behavior 😀), so a lot more study is needed here before any conclusions can be drawn. However, hormonally-mediated behaviors (maternal aggression, estrus behavior, inter-animal aggression in males, roaming, marking, breeding behavior, etc.) are common reasons for surrender or abandonment of dogs. And spare me the argument that those behaviors occur in S/N dogs. We accept without questioning "who can even live with an intact cat?" for the same behaviors. We have been castrating male livestock species and horses for >100 years because of the husbandry and housing challenges and safety risks of intact males. Why are we questioning if those same behaviors are hormonally mediated in dogs?? Why are we expecting the "average" owner to be capable or willing to manage intact dogs responsibly, when we don't expect the same of "average" horse or cat owners?
But, for me, the question of S/N, particularly for shelters and community health organizations, goes far beyond the health benefit/detriment analysis. Globally, there are 700-800 million dogs (and a similar number of cats)...up to 80% of which are considered free-roaming; 59,000 people die of rabies every year, mostly due to dog bites; in many places both cats and dogs have essentially become invasive species due to their impact on the environment, public health, and wildlife species; shelters and rescues in the U.S. are struggling and overwhelmed as unaltered adults and unplanned litters flood through their doors....management of those populations created by humans MUST be the priority, control of reproduction is key to that, and HQHVSN and pediatric/juvenile S/N are the most proven, safe, evidence-based methods to accomplish that. Dogs and cats often move between classifications (free-roaming, stray, sheltered, owned) throughout their lives so the impact of the decision of a shelter or private owner to delay or forego S/N for a pet may continue to ripple downstream for years. Are private pet owners who choose to forego or delay S/N actually making an informed decision that considers all the factors that affect that choice? Not if all they know is S/N might cause cancer or arthritis, according to social media or a click-bait headline.
From an access to care/cost of care standpoint, pediatric S/N is the most efficient, accessible, cost-effective method of reproduction control available. The costs and long-term health benefit/detriment analysis for non-surgical or novel surgical sterilization methods are almost entirely unknown and unstudied at this time. We should not presume that gonad-sparing sterilization would be a "win-win" for everyone. We should not "give it a try and see what happens".
For organizations that are adopting out intact pets but retaining ownership until S/N or creating contracts to ensure S/N...what will you do when that female dog develops pyometra? Will YOU be responsible for the $5-10k emergency surgery invoice? Will you pay the cost difference between juvenile S/N and adult S/N (often double, triple or more in cost at many private practices). If the adopter finds they cannot afford those costs/manage an intact pet and returns the pet how does that impact your capacity for care and surgical capacity? While most HQHVSN are comfortable with large/obese/in-heat S/N, there is no question those surgeries take longer and require more staff and financial resources...the more of them you do, the fewer total surgeries you can do with the same resources. What will you do when an adopter shows up at your door with an unplanned litter produced by the unaltered dog you adopted to them? Those puppies will be taking the place in your shelter and in adopter homes that was needed for all the puppies produced by dogs where we didn't have the opportunity to intervene before they arrived. At a time when there are far more dogs needing homes than there are adopters to take them. How will we identify shelter pets/owned pets that have had "gonad-sparing" procedures so that when they wind up back in the shelter system, we know their reproductive status, what diseases we need to be on the lookout for or what care they may require before adoption? Many will require repeated treatments (for non-surgical contraceptive methods) and have secondary sex characteristics that make them appear fully intact. Only 5% of private practice vets report tattooing sterilized pets as it is and microchip companies may or may not provide that information. We already spend a lot of time trying to discern if pet has been altered at the time of intake...what a nightmare if we start introducing novel methods of sterilization without figuring out how to address this problem.
All of this to say...this is a far more complicated issue than many have been led to believe, but I would argue it is neither a conundrum nor a controversial question in the shelter/rescue/welfare/access to care world. And I have barely scratched the surface in this post. This is the hill I will die on. Want to hear more? Come see my presentation on this topic at the Spay Alliance conference next week! #spayneutersaveslives
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Rachel Powell DVM
ASV Board of Directors
Director of Surgery
Greenhill Humane Society
Eugene, OR
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