You love your furry companion with all your heart, and you want to ensure their happiness and well-being in every way possible. So when it comes to the important decision of whether or not to spay your female dog, it’s natural to have questions and concerns. You might be asking yourself, “Does spaying change my dog’s personality? Are there any potential side effects I should be aware of?” or “Will spaying calm my energetic female dog?” We put together this comprehensive guide to help you understand how spaying can affect a female dog.

Why Spaying Your Dog Is Important

When you choose to spay your dog, you’re not only preventing unwanted puppies but also contributing to the control of pet overpopulation. Every year, millions of healthy dogs and cats in the U.S. are put down due to a lack of available homes.

While the traditional age for spaying dogs is six to nine months, puppies as young as eight weeks old can be spayed as long as they are healthy. Adult dogs can undergo spay surgery as well, but there is a slightly higher risk of postoperative complications in older dogs who are overweight.

Health Benefits of Spaying a Female Dog

There are significant medical benefits to be gained from spaying your dog, including the prevention of cancer, infection, and disease.

Mammary (Breast) Cancer

Spaying female dogs prior to their first estrus, or heat cycle reduces their risk of developing mammary cancer, which is common in unspayed female dogs. The chances of developing this cancer increase if a female does not undergo spay surgery until after her second heat cycle, but they still remain lower than the risk for unspayed females. If your dog has already had her first heat, it’s not too late. Spaying will still reduce her risk of developing cancerous mammary tumors.


Hormonal changes in the reproductive tract can sometimes cause a dangerous and potentially fatal infection of the uterus called pyometra. Infections usually occur in older females about seven to eight years of age. Approximately 25% of all unspayed females will suffer from pyometra before the age of ten. Having your dog spayed greatly reduces the possibility that she’ll contract this infection.

Contact us if you notice any of the following symptoms of pyometra:

  • Lethargy
  • Depression
  • Anorexia
  • Excessively drinking water
  • Vaginal discharge
  • Excessive urination
  • Pale mucous membranes (the skin inside her mouth and nose)
  • Vomiting
  • Diarrhea
  • Weight loss
  • Abdominal distension
  • Inflamed eyes

Ovarian and Uterine Tumors

Although they are uncommon in dogs, some breeds may be genetically predisposed to developing ovarian and uterine tumors. Older female dogs also have an increased risk. Spaying your dog completely eliminates the possibility of her developing ovarian or uterine cancer.

Injury, Stress, and Disease from Having Puppies

Carrying and giving birth to puppies can be very stressful on a dog’s body. It can also cause certain injuries and diseases, some of which can spread to the puppies. Spaying eliminates the risk of milk fever, brucellosis, and other reproductive disorders.

Does Female Dog Behavior Change After Spaying?

Dogs become sexually mature between six and twelve months of age. At this time, female dogs produce a surge of the hormone estrogen and begin their reproductive cycle, which leads to estrus, or “heat.” When in heat, a female dog will be receptive to breeding with males. Most dogs experience two heat cycles per year.

Spaying your dog will not affect her working abilities, friendliness, playfulness, or personality. However, female dogs may experience positive changes in behaviors associated with the heat cycle after spaying. You may see a reduction in the following unwanted behaviors after you spay your female dog:


Female dogs often try to leave home in search of males, which puts them at risk of getting lost and injuring themselves (sometimes fatally) on roadways. Spaying your dog will reduce or eliminate her drive to roam while in heat. If you do not spay your dog, you will need to confine her indoors or in an escape-proof yard when she’s in heat to prevent escapes and pregnancy.

Frequent Urination

Females in heat urinate frequently to attract male dogs with its scent. Not only will this cause a line-up of neighborhood male dogs at your door, but it can also lead to urine stains on your carpet and furniture. Spaying your dog will eliminate frequent urination and bloody discharge, both of which may occur during her heat cycle.


Each heat cycle causes significant hormonal changes in a female dog. Some become irritable or nervous and even feel pain due to ovulation. Because dogs don’t experience these hormonal changes after spay surgery, a spayed female dog’s behavior may be more consistent.


Unspayed females sometimes compete for the attention of a male dog by fighting. Spaying your dog reduces any aggressive behavior patterns so your dog will likely be less aggressive toward people and other dogs after spay surgery. 

Aggressive Guarding

Female dogs will sometimes behave aggressively if people or other animals attempt to approach or touch their puppies. Some dogs who don’t get pregnant during a heat cycle will experience a “false pregnancy” or “pseudopregnancy.” Females in false pregnancy often “adopt” objects and treat them like a litter that they will aggressively guard as if the objects were real puppies.

Preventing These Unwanted Behaviors

To prevent the development of these behaviors, it’s best to spay your dog before she reaches sexual maturity. That way, she’s unlikely to develop difficult habits associated with her heat. If your dog has been exhibiting these habits for months or years, they might persist even after spaying. 

If you have an older dog, it’s still worthwhile to spay her. Even if spaying doesn’t get rid of her problematic behaviors entirely, you might see them less often afterward, and spaying will still be beneficial to her physical health.

If your dog still has habits you dislike after spaying, it’s best to seek professional advice, especially if your dog is particularly aggressive. Discuss your dog’s aggression with your vet to determine if the behavioral issues stem from a treatable medical condition or if your dog needs professional training.

Common Myths About Spaying

Don’t Spay Your Dog Until After Her First Heat

There’s no behavioral or medical benefit to waiting to spay your dog until after her first heat cycle. In fact, each heat cycle your dog experiences increases her risk of developing serious medical conditions. To best prevent the development of unwanted behavior and medical problems, make plans to spay your dog before she reaches sexual maturity at six to twelve months of age.

Letting a Dog Have One Litter Will Calm Her Down

There’s nothing magical about giving birth that leads to a calmer, better-behaved dog. Two things that do lead to a better-behaved dog are proper obedience training and regular exercise. If you use gentle, consistent training techniques to teach your dog some basic manners, she’ll learn how to control her impulses. 

Making sure your dog gets at least 30 minutes of aerobic exercise per day, as well as plenty of mental exercise, can also greatly improve her behavior. If you have a puppy, keep in mind that maturity may lead to calmer behavior as well.

Spaying Is a Quick Fix for All Behavior Problems

Some people think that spaying a dog will get rid of all her behavior problems. Although it often reduces undesirable behaviors caused by the heat cycle, there’s no guarantee that your dog’s behavior will change after spay surgery. 

The effects of spaying largely depend on your dog’s individual personality, physiology, and history. Although spaying can remedy hormonal behavior problems, it’s not a quick fix that will instantly transform your dog into an angelic companion. If you want her to learn polite manners, you still need to teach her basic obedience skills. 

Potential Side Effects of Spaying Your Dog

Although spaying is beneficial in many ways, there are a few potential effects to be aware of:

  • A small number of studies report that unspayed female dogs who are aggressive to family members may become more aggressive after they’re spayed. This could be caused by a decrease in estrogen and oxytocin, both of which may have calming, anti-anxiety effects.
  • Spay surgery increases the risk of developing urinary tract infections in females.
  • Five to twenty percent of spayed females suffer estrogen-responsive urinary incontinence (or “spay incontinence”), which means they have poor sphincter control and are less able to hold their urine. At least one study found a slightly higher risk in dogs who were less than three months of age when spayed. The risk is higher for overweight dogs, and dogs of certain breeds. Fortunately, this kind of urinary incontinence is almost always easily controlled with medical treatment.
  • Dogs who undergo spay surgery before they reach their adult size may grow slightly taller than they would have without spay surgery.
  • Spay surgery could slightly increase the risk for dogs to develop transitional cell carcinoma of the bladder, osteosarcoma, and hemangiosarcoma—particularly breeds that are already predisposed to these types of cancer.
  • Spaying dogs prior to five months of age may slightly increase their risk of developing hip dysplasia and cranial cruciate ligament (CCL) rupture, especially in breeds that are already predisposed to these conditions.
  • Spay surgery can increase a dog’s of developing hypothyroidism.
  • Physiological changes after spaying may affect your dog’s metabolism and appetite, making her prone to weight gain. Spaying puppies before they are five months of age could put them at greater risk of becoming obese. This potential drawback is easily controllable using an appropriate diet and exercise. If you notice that your dog looks overweight, you can decrease the amount of food you give her and increase her exercise. If you’re not sure if your dog is at a healthy weight, please consult a veterinarian.

Spay Surgery in Gilbert, AZ

The benefits of spaying your female dog far outweigh the potential drawbacks. However, knowing whether surgery is right for your dog requires a visit with an experienced vet. At Anasazi Animal Clinic in Gilbert, AZ, we provide a variety of affordable surgical services. To discuss spay surgery for your dog, contact us to schedule an appointment. 

Images used under creative commons license – commercial use (9/1/2021). Image by Pexels from Pixabay