Fixing a dog means surgically removing its reproductive organs so it can no longer breed. For female dogs, the procedure is called spaying, which involves removing the ovaries and usually the uterus. For male dogs, it’s called neutering, which involves removing the testicles. The term “fixing” is informal shorthand that covers both procedures, and it’s one of the most common surgeries performed on pets in the United States.
Spaying vs. Neutering
Though people use “fixing” as a catch-all, the surgery itself differs depending on your dog’s sex. Spaying is a more involved abdominal surgery. The veterinarian makes an incision in the belly to access and remove the ovaries and uterus. Neutering is typically quicker and less invasive, with a small incision near the scrotum to remove both testicles. Both surgeries are performed under general anesthesia, and your dog goes home the same day in most cases.
Complication rates for these elective surgeries are low. Research across private veterinary practices found that overall postoperative complications ranged from 1% to 24% (most of those being minor issues like mild swelling), while severe complications occurred in only 1% to 4% of cases.
Why People Fix Their Dogs
The most straightforward reason is preventing unwanted litters. Beyond that, fixing offers several health advantages, though the picture is more nuanced than many pet owners realize.
For females, the biggest benefit is a dramatic reduction in mammary tumor risk. A landmark study found that dogs spayed before their first heat cycle had just 0.5% of the mammary tumor risk compared to intact dogs. After one heat cycle, the risk climbed to 8% of that baseline. Dogs spayed after their third cycle had mammary tumors at nearly three times the rate (27.6%) of those spayed earlier (9.4%). Spaying also eliminates the risk of pyometra, a life-threatening uterine infection that’s relatively common in unspayed older dogs.
For males, neutering eliminates the possibility of testicular cancer entirely since the testicles are removed. However, one area where the data may surprise you: research has found that neutered males actually have a higher risk of prostate cancer compared to intact males. This runs counter to what many people assume, and it’s worth discussing with your vet if you have a breed that’s already predisposed to these cancers.
How Fixing Affects Behavior
Many owners fix their dogs partly for behavioral reasons, and the surgery does reliably reduce certain hormone-driven behaviors in males. Early research found that roaming decreased in about 90% of neutered dogs. Fighting with other males, urine marking indoors, and mounting people or other dogs also tend to decline. These behaviors are directly tied to testosterone, so removing the source has a predictable effect.
The picture gets murkier with aggression. Some studies show neutering reduces aggression toward other dogs and animals, but others have found the opposite: neutered males sometimes display more anxiety during walks and increased aggression toward other dogs. Aggression toward owners and strangers has gone both directions in different studies. Neutered males were also more likely to guard resources like food or toys compared to intact dogs. The takeaway is that fixing your dog is not a reliable fix for aggression problems, which are often shaped by learning, socialization, and individual temperament rather than hormones alone.
Timing Matters, Especially for Large Breeds
When to fix your dog is just as important as whether to do it, and the answer depends heavily on size. The American Animal Hospital Association recommends the following guidelines:
- Small breeds (under 45 lbs as adults): Males can be neutered at 6 months. Females should be spayed before their first heat cycle, typically around 5 to 6 months.
- Large breeds (45 lbs or more as adults): Both males and females benefit from waiting until growth stops, roughly 9 to 15 months of age.
The reason for the difference is joint and bone development. Research across 35 breeds found that dogs neutered before one year of age, particularly those done by 6 months, had two to four times the risk of joint disorders like hip dysplasia and cruciate ligament tears compared to intact dogs. This was especially pronounced in large breeds like Golden Retrievers, Labrador Retrievers, and German Shepherds. Some breeds also showed increased cancer risks (lymphoma, mast cell tumors, and bone cancer) when fixed early. Smaller breeds generally showed little to no increased risk from early neutering.
For female large-breed dogs, there’s a genuine tradeoff: spaying earlier protects against mammary tumors and unwanted pregnancies, while waiting until growth stops reduces the risk of orthopedic problems and certain cancers. Your vet can help you weigh these factors based on your specific breed.
What Recovery Looks Like
The first 24 hours after surgery, your dog may seem groggy, wobbly, or irritable from the anesthesia. Some dogs shiver or vocalize. This is normal. Offer small amounts of food and water that evening, keeping in mind that nausea can suppress appetite for up to 48 hours.
The critical recovery window is 10 to 14 days. During this time, your dog needs strict activity restrictions: no running, jumping, swimming, or rough play. Strenuous movement can cause swelling around the incision, dissolve the sutures prematurely, or reopen the wound. Check the incision twice daily for signs of infection. A small amount of redness and swelling is expected, but excessive discharge or spreading redness is not. Keep the incision dry, and use an E-collar (the plastic cone) if your dog tries to lick or chew at the site.
One detail that catches some owners off guard: male dogs can still impregnate a female for up to a month after neutering, since viable sperm can remain in the reproductive tract for weeks after the testicles are removed.
Cost of Fixing a Dog
At a private veterinary clinic, expect to pay around $300 for a dog spay or neuter, though this varies by region, the dog’s size, and the specific clinic. Larger dogs cost more because they require more anesthesia and longer surgical time. Many local shelters and community programs offer low-cost or even free spay and neuter surgeries, making the procedure accessible regardless of budget. The ASPCA and local humane societies are good starting points for finding affordable options in your area.