For over 50 years, the concept of spaying and neutering pets to control the pet population has been in place. It first became a “thing” in the 1930’s, although at that time it was largely marketed as an option for owner convenience to avoid messy heat cycles and unwanted puppies and kittens.
In 1969, the first spay-neuter clinic opened in California. What had begun as an owner convenience had become an animal welfare issue and a necessity to manage the pet population. Strays were overwhelming the shelters. In 1972, the ASPCA required that all adopted animals need be neutered. Currently, the euthanasia rates in shelters have dropped 90% from 50 years ago.
The most recent debate is about the relative merit of spaying and neutering at all, and what the optimal time might be. Taking current data into consideration, there is no single perfect answer across all scenarios for whether to, and when to, spay or neuter a pet. Shelter animals continue to be neutered before adoption, regardless of age. House pets should be considered as individuals with their own individual circumstances – which includes their health status, inherent breed risks for neutering/spaying or not, and as well as the ability of their guardians to tolerate heat cycles and prevent unwanted pregnancy.
For each pet guardian, the line will vary what they are prepared to accept, manage or mitigate in the consideration of future health risks, heat cycles in females or some behavioral issues (predominantly in males). Proposed increased health risks of neutering/spaying include (percent varies by breed): hip dysplasia, various cancers, obesity, ACL (cruciate ligament) tears, urinary incontinence, and cognitive impairment. Proposed decreased health risks include: pregnancy, pyometra, various cancers, perineal hernias, roaming, and aggression.
Arguably, many of the above -on either side of the issue – can be managed by good health care, attentive guardianship, and good breeding practices. Obesity should not be an issue if pet guardians are in tune to the changing caloric needs of their pet. Pregnancy should not happen if dogs are appropriately supervised. Cognitive impairment can be reduced by environmental enrichment – similarly to how it is managed in humans. Hip dysplasia and behavioral issues are multi-factorial, and the incidence of these would be difficult to fully attribute to neutering (or not) at any point. ACL injuries and urinary incontinence are quite treatable. It is generally held that spays done prior to the first heat largely eliminate the risk of mammary cancer (which has a poor prognosis).
The Center for Disease Control deals with 4.5 million bite wounds per year in North America. 37% of these bites are on kids. A study done by the American Veterinary Medical Association noted in 2001 that 70-76% of bites come from intact male dogs.
One issue with adult age spay/neuter is the tougher recovery on adult and especially larger breed pets through increased pain (nerve sensation development), surgery duration, and a blood supply that has further increased with the pet’s maturity (potential for increased surgical risk). This inherently also leads to a more expensive surgery fee.
The bottom line… In April 2018 I listened to a specialist at a conference who has been reviewing studies on spay/neuter impact annually over the past few years. He has continued to conclude that there is inadequate information to suggest spay at 6 months of age is an issue in small dogs, especially since they are mature at their first heat (6-7 months of age). His summary is this:
Small and large female dogs and female cats – spay early in life
Male cats – neuter
Small male dogs – discuss pros and cons
Large breed male dogs – discuss pros and cons, and consider delaying neuter until 1 year of age, particularly if breed has an increased risk of certain cancers (HSA, OSA)
There are other alternatives to spay and neuter, which include chemical sterilization, ovary sparing surgery (leaving ovaries/hormones in the body and removes the uterus alone), and ovariectomy (removes ovaries, but not the uterus). These have their own pros and cons and are beyond the scope of this article.
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