What Are the Side Effects of Spaying a Dog?

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When it comes to a dog’s healthcare, honesty is important. Spaying a dog can come with side effects and possible risks. We’ll explain some of the common risks and side effects so you will know what your dog might get into. Here are some common side effects of spaying a dog:

  • Unspayed female dogs such as bull terriers who were aggressive before may become more aggressive after they’re spayed. The main reason may be attributed to a decrease in estrogen and oxytocin which induces calming and anti-anxiety effects.
  • Spayed female dogs have an increased risk of developing urinary tract infections.
  • Some female dogs may find it hard to control their urine. The risk is higher for certain breeds and overweight dogs. However, it can be easily treated with medical options.
  • Dogs that are spayed before reaching adult size may not grow as tall as dogs who aren’t spayed or spayed after reaching adult age.
  • Dogs spayed before five months of age may slightly more likely to develop hip dysplasia and cranial cruciate ligament (CCL) rupture.
  • Spayed dogs have an increased risk of developing hypothyroidism.
  • Dogs may experience changes in metabolism and appetite after spaying.

If you do spay your dog and it develops any metabolism issues, that you need to seek veterinary advice rather than trying to solve the issue on your own.

Health Risks of Spaying a Dog and What Research Says

We are not saying spaying is bad. Just like any other surgery, you might get complications. That’s why we make sure that the dog gets the best treatment possible.

Here are some of the common diseases of dogs and how they relate to spaying a dog. It’s important for us that you know more about the health risks for specific breeds.

Complications after Surgery

All types of surgery have their risks of complications. These could be adverse reactions to anesthesia, hemorrhage, inflammation, infection, and many others.

However, it shouldn’t worry you too much. The rate of complication after surgery is between 6% to 23%, with serious complications only around 1% to 4%. The death rate is even lower, around 0.1% to 2%.

As long as you have a competent and experienced veterinarian and the right environment for your dog, they will recover and feel at ease after surgery.

Prostate Cancer

A common belief among dog owners is that spaying reduces the risk of prostate cancer. Some even argue that it increases the risk. Studies are even at a crossroads with varying results.

What you need to know is that prostate cancer is pretty uncommon in dogs. Dogs develop prostate cancer 0.6% to 5% rate. Hence, it’s really difficult to attribute the risk of prostate cancer to spaying.

Testicular Cancer

In spaying or neutering males, the testicles are removed. This means it removes any risk of testicular cancer. However, it doesn’t work if the cancer is already developing in the testicles.

Testicular cancer isn’t that common in dogs either. We wouldn’t resort to spaying the dog just to avoid testicular cancer. Only if its parents also have a history of cancer, we will consider spaying the dog.

Osteosarcoma (Bone Cancer)

A study found that spayed or neutered dogs had twice the risk of developing osteosarcoma compared to intact dogs. This is especially true for Rottweilers which already have a high risk of osteosarcoma.

The risk of osteosarcoma increases with the increase of breed size and height of the dog. It is even among the common causes of death in medium, large, and giant breeds. We would advise thinking twice about spaying the dog if they are in the large breed category.

Breast Cancer

Mammary tumors are the most common tumors you can find in intact female dogs. Most of the time, these tumors are malignant. This may develop into breast cancer. Spaying female dogs significantly reduces the risk of developing breast cancer.

Female Reproductive Tract Cancer

Uterine or cervical tumors are fairly rare in dogs. It’s only 0.3% of tumors found in dogs. Spaying will remove the risk of ovarian tumors. However, we wouldn’t undergo spaying a dog only for this reason. It’s not worth it because of its low rate appearance.

In this case, we will consider spaying if there are multiple risks aside from my dog getting female reproductive tract cancer. The risk of getting it is so low that it doesn’t justify getting your dog spayed. 

Urinary Tract Cancer

Spay or neutered dogs are two times more likely to develop urinary tract tumors compared to intact dogs. They’re highly likely to be malignant. However, it only accounts for 1% of canine tumors which means it rarely forms.

Certain breeds are also more susceptible to urinary tract cancer like Airedales, Beagles, and Scottish Terriers.


Hemangiosarcoma is a common cancer among dogs. It is even the major cause of death among certain breeds. A lot of studies have shown that the risk factor increases in spay or neutered dogs.

This is one of the most important things we consider before spaying a dog. We make sure to factor in the increased risk of certain breeds and whether to proceed with spaying the dog.


Because of the changes in the metabolism of spayed dogs, they are more likely to become overweight or obese. That’s why it’s important that you observe any behavioral changes in your dog after surgery.

An obese dog has a higher risk of developing health problems. We often recommend getting professional advice from an animal behaviorist or a certified dog trainer.


Diabetes is also found in dogs. However, there are no significant studies that connect diabetes with spaying a dog. It’s more likely that dogs may develop diabetes due to the behavioral changes accompanied by spaying.


Spaying a dog, while also beneficial, also has its risks. It’s important that you seek professional advice before deciding to spay your dog. Veterinarians know best when a dog should be spayed or when not to.  

About the Author

Madison Finley is the founder and editor of Terrier Hub. She is passionate about helping fellow pet parents make the best choices for their pets through her blog.

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