To spay/neuter or not to spay/neuter? There was a time when this answer was straightforward. All non-breeding pets should be spayed/neutered, and it should be done early. No equivocation and no doubt. Now this simple answer is being challenged. New evidence has risen that has everyone questioning when and whether spaying/neutering should be done for a pet.

It’s always good to question long-held health recommendations. It is only through a good debate that we can ensure a thorough review of new medical data and how that might impact a recommendation. Ultimately, when dust settles from such a conversation we usually have a new improved recommendation.

Right now, it appears that veterinary medicine has begun such a debate, and we are focusing on our spaying/neutering recommendation. At the heart of this debate is whether spaying/neutering has any long-term health impacts on our pets. This question was raised due to a series of recent publications that would suggest an associated risk for certain diseases after spaying/neutering or when spaying/neutering occurs before puberty.

photo credit: jaumescar

Critical review of these publications is required before we change our current recommendation. Sitting in a recent day-long forum on this topic has allowed me to evaluate better some of this new information. Of the diseases that are getting most of the press about this issue, orthopedic or joint diseases appear to have the strongest and cleanest data. Simply, the data suggest a possible increased risk for the formation of joint disease in animals who were spayed/neutered prior to puberty. In full disclosure, however, the evidence is not 100% supportive, only very suggestive.

It’s very tempting to speculate on the correlation between orthopedic diseases and puberty. For example, closure of growth plates occurs during and immediately after puberty. In animals who were spayed/neutered prior puberty these growth plates stay open longer. When this happens, the bones will continue to grow for longer than programed by nature. This increased growth very likely changes the angles of a joint and even the bones involved in the joint. It is very possible these changes will increase stresses on these joints or the joints will form incorrectly. The assumption is that these abnormal joints will lead to juvenile and chronic joint disease.

Additionally, new evidence is emerging that suggests puberty helps mature ligaments and tendons. It is known that the strength of these will ultimately affect the function of a joint. Therefore, in addition to changing the duration of growth plate activity, we may be affecting the health of the ligaments and tendons of the joints. These both would suggest very good reasons for this potential association between early spay/neuter and joint diseases and puberty.

Orthopedic diseases are not the only disease suggested to be impacted by spaying/neutering. It has been suggested that cancer risks are linked to both spaying/neutering and the timing of these procedures. However, unlike the publications focusing on orthopedic diseases, these reports are not nearly as suggestive or supportive of a link between spaying/neutering and cancer. There are some serious biases and issues with the populations of animals studied in these papers. The problems in some cases almost negate any impact of spaying/neutering on cancer formation. That being said, there is some very good and intriguing data that should be explored further, especially the impact of stopping puberty and cancer.

As we debate spaying/neutering we must consider once again why the current recommendations were developed. We have a very serious stray pet population problem in the United States. This problem, despite decades of our best efforts, is not yet solved. As a matter of fact, recent statistics indicate that over 4.3 million animals every year will enter a shelter. Only 15.8% of the dogs and 2% of the cats will be reunited with their families. Of the remaining animals, only 25% of the dogs and 24% of the cats will be adopted. Sadly, all the rest will be euthanatized (roughly 2.7 million) or 60% (1.2 million) stray dogs and 74% (1.4 million) stray cats. We clearly still have a stray pet population problem, and this must be part of our debate on spaying/neutering.

Some might ask, “Have the current recommendations for spaying/neutering decreased our stray population of animals?” Good question. Yes, there is evidence that this recommendation does work. For example, a recent publication on cats has shown a significant reduction in the number of cats brought into shelters when early spay/neuter or spay/neuter before adoption becomes the policy for that shelter. Thus, it appears that the current recommendation does work in certain populations.

The last aspect of this debate that should be brought to the table involves the data recently published from the Banfield Pet Hospital database. According to their database, dogs and cats that are spayed and neutered have a significantly longer life span, compared to intact dogs and cats. Why this significant difference exists is not currently understood. It must be recognized there may be many confounding influences on these populations. But as this data stands, it potentially flies in the face of all the data that suggests spaying/neutering increases health risks for pets.

This topic has many facets and many unanswered questions. It is a debate that has no resolution in sight, and has many complicating factors. Until the veterinary community develops our new recommendations, speak with your veterinarian about spaying/neutering. Have them help you weigh the risks and benefits of this procedure for your animal family member. These are the best people to help sort through this debate and to protect your pets’ health.

By Lisa Parshley, Olympia Veterinary Specialists. Visit their website at