banner.png

A New Perspective on Determining Best Age of Spay or Neuter

Updated: Feb 29, 2020

Common sense disclaimer: As with everything else on this blog, it’s critical to seek the advice of a qualified veterinarian, preferably one that is board certified in theriogenology (reproductive science) for reproductive matters. This website, its blog, and its courses are NOT designed nor intended to replace the need for a qualified veterinarian, but instead to help educate people to to work optimally with their veterinarians. All recommendations should be reviewed with qualified professionals, such as a board certified reproductive veterinarian, prior to implementation in a breeding program. Always seek the advice of your veterinarian. Readers assume all risks associated with use of material on this site. More here.

There have been studies done that show both benefits and risk to spaying and neutering at a young age. Some results have not been fully presented in the media.

Desexing has both physical and behavioral implications. Spay/neuter timing needs to consider the both the physical and behavioral ramifications of allowing a dog to remain intact. I'll cover both here, and also present a risk analysis of physical issues associated with spay/neuter (S/N).

Most families, however well-intentioned, are not prepared to deal with sexually mature dogs.


Both males and females can be fertile at six months of age. Many families don’t realize that dogs can even breed through many fences, so the longer you wait past sexual maturity to spay or neuter, the greater the risk of inadvertent breeding. Dogs previously not interested in escaping will suddenly find a way out of their yard when hormones hit hard and furiously.

Female behavioral concerns

  • Many families also are not comfortable dealing with multiple heat cycles in a female.

  • Females can cycle (“in estrus,” “in heat, “in season”) as early as 6 months.

  • Heat cycles involve needing to keep their dog and home clean as well as protecting their dog from accidental breeding.

  • Dogs in heat should never go outside unsupervised, even in a fenced backyard.

  • They are more likely to try to jump or dig out, and many dogs are resourceful enough to breed through fences.

  • Even if a female doesn’t get out or breed through the fence, a resourceful male can often jump or dig in.

  • Females in estrus need to be thoroughly secured from any potentially intact (unneutered) male dogs for the full 21 days (plus or minus 7 days) of each heat cycle. Heat cycles typically occur twice a year.

Male behavioral concerns

  • Males can smell a female in heat from as much as a mile or two away and will be attracted to a female’s location.

  • Males are also prone to marking near a female in heat, so even if a female is secure, families can expect intact males near the home to want to be in the area and mark by urinating on or near the home.

  • Males often get frustrated and aggressive with other dogs when they detect a nearby female in season.

  • Males also increase in other behaviors when around a female in heat, including humping, escaping, roaming, spraying, and more.

  • Males can start to exhibit hormone-related behaviors at about 6 months of age. Hormone-related behaviors are less likely to occur if an intact female isn’t around. However, since a male can smell a female in heat from a great distance, then nearby females can impact the propensity of a male to spray/mark, escape/roam, hump, etc. Unneutered males should never be allowed to roam freely or be off leash in public.

It is not an exaggeration to say that even if a pet parent is walking with their dog and she is on leash that a male can breed her. A male can approach and be on a female before the handler realizes what is happening. When dogs breed, they “tie” together, and once a breeding starts, it can be over quickly and the male will “tie” with the female, meaning he will be attached to her for as long as 30 minutes or more. Trying to separate them at that point can be painful and damaging to both dogs. Besides, once the tie has started, it’s too late to prevent pregnancy.

The recent spay/neuter (S/N) research is the latest thing people are overreacting to without looking into the details. This can include some veterinarians.

There are studies showing both advantages and disadvantages to desexing, either at an early age or at all.

In general, we do agree that EARLY S/N should be avoided when possible.

However, shelters have been performing early (less than 2-3 months) S/N for decades and we have yet to see the epidemics people seem to be predicting when reading these studies.

The bottom line advice from the American Veterinary Medical Association (AVMA) is “due to the varied incidence and severity