Apr 07 2014

When Should I Spay/Neuter My Pet?

Nicole Jewett

As many of you have probably heard, there has been a lot of discussion recently on the timing of the spay/neuter surgery. Is the best time at 6 months, 1 year, 2 years, or should it be done at all?

First, I will begin with a few definitions:

–       Ovariohysterectomy: removal of the ovaries and uterus in a female animal, also known as a spay.

–       Castration: removal of the testicles in a male animal, also known as a neuter.

There are many reasons why, historically, we have performed this procedure. The main reasons included prevention of un-wanted pregnancies, decreasing the likelihood of behavioral problems such as marking, roaming, aggression, etc. and simply, it is what we’ve been told to do.

According to the Human Society of the United States, there are 10 million dogs and cats in the shelters every year and of these, 3-4 million are euthanized. Over-population is a serious issue with 50% of animals born, are from un-planned litters. I think we all agree that spaying/neutering does play a very important role in reducing the numbers of unwanted pets. The bigger question, when is the right time to spay or neuter?

Several studies have been published trying to answer this very question. This research discovered that spaying/neutering can result in a multitude of health benefits as well as health risks. After reading these studies, over and over again, as well as reading the various discussions had by reproductive specialists around the world, I have an answer…it all depends!

There are a very large number of factors that play a role in deciding on the perfect timing. What is the intended use of the pet? Is going to be part of a breeding program, an athlete, a family pet? What breed is it? Does it have family history of certain diseases? Are there other pets in the household? What is the owner experience with intact animals? What is the pets’ temperament? These are all important factors to consider.

 Table1: Pros and cons of spay/neuter for various conditions for both dogs and cats.

As you can see, there are many pros and cons to spaying/neutering. For those of you wanting to spay or neuter, is there a specific age where the health benefits would outweigh the risks? There are many who think that delaying the time of spay/neuter will allow for the best of both worlds. Unfortunately, more research is needed to find this “perfect time”.

Many have suggested waiting until the majority of the growth is finished, especially in larger breed dogs (~ 18 months of age). Due the risk of mammary cancer, some suggest females should be spayed before their 1st heat (6-9 months of age). Every pet is different. The pet owner should have a discussion with their veterinarian to look at the pros and cons and decide together which is best for their pet.

 Here is an example of one such discussion:

– Owner visits their veterinarian with an 8-week old, female, labrador retriever puppy with which the owner has no plans to use for breeding. This dog would benefit from being spayed before her first heat due to the greatly reduce the risk of mammary cancer. Because of her breed, she would be at a slightly higher risk for CCL injury, hemangiosarcoma and obesity. However, there is a low risk of hemangiosarcoma and obesity could be easily prevented with good feeding practices and exercise, which leaves CCL injury the most important possible detriment to the spay procedure. Since the risk of mammary cancer is much higher then a CCL injury, the veterinarian may recommend to have her spayed before her first heat, typically 6-9 months of age.


Root Kustritz, MV. 2007. Determining the optimal age for gonadectomy of dogs and cats. JAVMA, Vol 231, No. 11

Hoffman JM, Creevy KE, Promislow DEL (2013) Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs. PLoS ONE 8(4): e61082. doi:10.1371/journal.pone.0061082


Torres de la Riva G, Hart BL, Farver TB, Oberbauer AM, Messam LLM, et al. (2013) Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. PLoS ONE 8(2): e55937. doi:10.1371/journal.pone.0055937


Harrell B, Freshman J. Oct 13/13. The best age for spay and neuter surgery. VIN Rounds

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