If you read dog magazines or belong to dog groups on social media, you have probably noticed that canine spay/neuter surgery timing has become a “hot topic” in recent years. 

Historically, veterinarians have recommended spaying or neutering dogs before they reach five to six months of age, to prevent pet overpopulation and prevent medical issues that can arise in intact (unneutered) pets. In the last ten years, however, several studies have suggested that there may be risks associated with early spay/neuter in some dogs. These findings have led to heated debate about the optimal timing for canine spay/neuter, and this debate is still ongoing. 

What Is the Evidence Fueling the Spay/Neuter Debate?

Here’s a summary of studies that have fueled the debate, listed in chronological order: 

  • A study of 759 golden retrievers found that spaying or neutering golden retrievers before one year old increases their risk of hip dysplasia, cruciate ligament tear, lymphoma, and hemangiosarcoma.
  • A study of approximately 70,000 dogs found that spayed and neutered dogs live longer than intact dogs. Spayed and neutered dogs are more likely to die of cancer (an old age problem), while intact dogs are more likely to die of trauma and infections (at an earlier age).
  • A study of over 1,000 goldens and 1,500 Labrador retrievers found that both breeds were more likely to develop orthopedic conditions if neutered early.
  • A study of 1,170 german shepherds found that those spayed or neutered before their first birthday were roughly three times more likely to develop an orthopedic disease than dogs spayed or neutered later in life.
  • A study of 90,000 dogs found an increased risk of immune-mediated diseases in neutered dogs.
  • A study of 35 dog breeds found large-breed dogs (with the exception of Great Danes and Irish wolfhounds) are at a higher risk of cancer and orthopedic disease when spayed/neutered early, but this correlation does not exist in small-breed dogs. 


After reading these studies, you may be already starting to develop some conclusions. But first, let’s give these findings some more context. 

Why Have We Historically Focused on Early Spay/Neuter?

Dogs can become sexually active as early as six months of age. Spaying or neutering them prior to this time provides the greatest benefits in controlling pet overpopulation. However, there are also medical benefits to performing this surgery early, especially in females. 

Spaying dogs at an early age dramatically decreases their risk of mammary cancer. According to the American College of Veterinary Surgeons, a dog that is spayed before her first heat cycle has only a 0.5% risk of developing mammary cancer during her lifetime. That risk increases to 8% if she is allowed to go through a single heat cycle, or 26% after going through two heat cycles. Spaying a dog at a young age also eliminates the risk of pyometra, a life-threatening uterine infection.

Neutering male dogs eliminates the risk of testicular cancer and dramatically reduces the risk of prostatic hypertrophy (enlargement). Additionally, neutered dogs are less likely to roam, making them less likely to suffer trauma (dog fights, hit-by-car injuries, etc.) or run away from home. 

What Should You Do with All of This Information?

Now that you have been thoroughly overwhelmed with facts, you need to analyze this information to make the best decision for your dog. 

First, let’s review the studies from the last several years. The overall message is that large-breed dogs may be at higher risk of certain cancers and orthopedic conditions if they are spayed or neutered at an early age. The same distinction does NOT appear to hold true for small-breed dogs. 

If you own a small-breed dog, have them spayed or neutered prior to six months old. Spaying your small-breed female before her first heat cycle will nearly eliminate her risk of mammary cancer. Spaying your small-breed male at an early age will reduce his risk of roaming (and associated trauma) and ensure that he doesn’t contribute to pet overpopulation. There don’t seem to be any drawbacks associated with early spay/neuter in small-breed dogs. 

If you have a large-breed dog, however, your decision becomes a bit more complicated. Early spay/neuter may increase your dog’s risk of certain orthopedic conditions and cancers. However, delayed spay/neuter may place your dog at a higher risk of trauma, infection, and (in the case of females) mammary cancer. You will also need to make a concerted effort to keep your dog confined to prevent roaming and unintended breeding, which can be challenging with a large dog. The American Animal Hospital Association currently recommends that large breeds be spayed/neutered after they are finished growing, but this may not be the best choice for every family. Talk through this decision with your veterinarian, weighing the pros and cons of each approach.

There’s No Easy Answer for Spay/Neuter Timing in Large-Breed Dogs

If you own a small-breed dog, your decision is easy: spay or neuter your dog at an early age. If you own a large-breed dog, however, it’s a tough decision and you must carefully weigh the tradeoffs of each approach. Talk to your veterinarian to get an idea of the suspected risks and benefits for your individual dog and your specific situation. 

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