Spaying and Neutering: To Fix, or Not to Fix?

Spaying and Neutering: To Fix, or Not to Fix?

One of the most common questions from cat and dog owners is, “Should I spay or neuter my pet? If so, when?” There is a plethora of information available on the subject, and new research has been released within the past few years. The short answer is that while there are clear benefits to removing reproductive organs, there are pros and cons to every procedure. Below is a brief summary of what we currently know.

Image result for birthday cake for dogs images with candlesGeneral points for both cats and dogs

There is not a single perfect age to spay or neuter an animal.

Some shelters may need to have animals fixed prior to adoption, or risk having them come back with puppies a few months later. Animals with owners may be able to have surgery slightly later in life.

Pet overpopulation is an enormous problem. Up to 10,000 dogs and cats are euthanized in US shelters every day. The focus on spaying and neutering in the past fifty to sixty years has dramatically decreased the amount of healthy animals being put down, but there are still far too many dogs and cats dying due to overpopulation. If you choose to keep your pet intact, can you absolutely guarantee that they will not be contributing to this problem? Can you ensure a good home for any expected (or unexpected) offspring, and deal with the potential expenses of a pregnancy? Remember, if your pet needs an emergency cesarean section, it could cost hundreds or even thousands of dollars to deliver the babies.

Spaying or neutering will slow an animal’s metabolic rate. For both cats and dogs, removing their reproductive organs will slow their metabolism down. This means if they are fed the same amount of food that they were prior to surgery, they will gain weight! Obesity is a huge problem for pets: 50-60% of dogs and cats in the US are overweight or obese, and this predisposes to many serious health concerns. However, obesity is also a preventable condition. If appropriate amounts of food are provided, your pet will not become overweight after being fixed. Your vet can help you adjust their nutritional plan to maintain them at an ideal weight.

There are also concerns and benefits specific to different types of pets.

Male cats Benefits of neutering: less roaming, spraying urine, and fighting

Especially if you want an indoor pet, an intact male cat can be a real challenge. They will constantly be attempting to escape to find females. They will also tend to mark their territory with urine — and intact male cat urine has a very strong and distinctive odor!

More importantly, intact male cats are at much higher risk of being hit by a car or attacked by other animals, because they will tend to roam farther from home.

Risks of neutering: obesity As stated above, gaining weight post-neutering can be prevented with an appropriate diet.

Conclusion: For male cats, the data is fairly straightforward. There are few major downsides to neutering, and many clear benefits. For most cats, the behavioral benefits will be most pronounced if they are fixed prior to the onset of sexual maturity, which means the procedure should be done at approximately six months.

Image result for pyometra cats symptoms

Female cats Benefits of spaying: eliminates risk uterine infection (pyometra) as well as uterine and ovarian cancer, significantly decreases risk of mammary cancer, behavioral benefits

Up to a quarter of intact female cats will eventually develop a life threatening uterine infection. If this occurs, the only true cure to is surgically remove the uterus–which means that they would end up being spayed, only in an emergency setting when they are sick. This risk can be eliminated with spaying.

Spaying before the onset of a female cat’s first heat makes it significantly less likely that she will eventually develop mammary cancer. Since up to 90% of feline mammary tumors are malignant, this is a clear benefit.

Additionally, female cats in heat are not ideal pets — they are loud, persistent, and intent on escaping.

Risks of spaying: obesity

Conclusion: For female cats as well, the benefits of spaying are very clear. The current medical recommendation is to spay all female cats prior to the onset of sexual maturity, meaning at or before six months.

Image result for male dogs fighting over female dog

Male dogs Benefits of neutering: decreased roaming, decreased risk of perineal hernias, perianal adenomas, and benign prostatic hyperplasia, eliminates risk of testicular tumors

Just like male cats, male dogs are more likely to get into fights, or to get hit by a car. In fact, intact male dogs are twice as likely to be hit by a vehicle!

Certain medical issues are less common in neutered dogs, including some benign masses, as well as an enlarged prostate, which can cause difficulty urinating.

Risks of neutering: possible increase in certain types of cancers and orthopedic concerns.

Certain studies, performed mainly on purebred dogs, have shown an increase in certain types of cancer (transitional cell carcinomas, osteosarcomas, and hemangiosarcomas) in neutered dogs. Again, these studies were done on a specific breed, and cannot necessarily be extrapolated to all breeds.

Additionally, since many purebred dogs are already more prone to certain types of cancer, there are confounding genetic factors.

Some studies have also shown a possible increased risk of cranial cruciate rupture and hip dysplasia after neutering. Veterinary medicine is very early in its research into this subject, and there have been some conflicting results. This concern is most likely more of an issue for large breed dogs that are neutered prior to the onset of skeletal maturity.

Conclusion: There are both clear benefits and possible risks to neutering dogs. There is not one clear choice that is right for every owner and every pet.

Some owners may wish to consider delaying neutering,

especially in large breed dogs, until > 1 year of age.

Female dogs: Benefits of spaying: eliminates risk of pyometra (uterine infection) as well as ovarian and uterine neoplasia, decreased risk of mammary neoplasia, messiness factor. Image result for mammary cancer in dog

Similar to female cats, intact female dogs can also develop severe uterine infections. They also have a sharply decreased risk of mammary cancer if spayed prior to onset of their first heat. Owners may also wish to consider the logistical issues of having a female dog in heat in their house — it is not a clean process!

Risks of spaying: possible increase in certain types of cancer and orthopedic issues, urinary incontinence

As stated above, there is some new research which raises concerns for possible increased risk of some types of neoplasia, as well as cruciate ligament tears in spayed female dogs. Again, this is limited to a few studies done on purebred dogs.

One other concern unique to female dogs is that spaying increases the risk of eventual urinary incontinence. Between five and twenty percent of spayed female dogs (most likely closer to the low end) will develop urinary incontinence several years after being spayed. However, this condition generally responds well to medical therapy.


Conclusion: In general, the benefits of spaying female dogs outweighs the risks. Most female dogs should be spayed prior to their first heat, meaning at or before six months. Some owners of large breed female dogs may wish to delay this due to concerns for future orthopedic issues. However, that will likely increase their risk of developing mammary cancer.


Deciding whether or not to spay or neuter your pet is a serious decision, and should not be taken lightly. Remember to talk to your veterinarian if you have specific concerns or questions!


Berg, J. (2016). The Spay/Neuter Controversy. OVMA 2016. Retrieved January 5, 2018, from

Miller, K. (2016). The Spay/Neuter Debate: When, Why, What if… Southwest Veterinary Symposium 2016. Retrieved January 5, 2018, from

Ramsubeik, S. (n.d.). The Benefits and Risks of Spaying and Neutering. 39th Annual OAVT Conference & Trade Show. Retrieved January 5, 2018, from