Can a Spayed Dog Still Go Into Heat?

When your female dog is in heat (also called estrus), it can make for an unpleasant experience for everyone in the house. Not only do dogs in heat experience fluctuating hormones, but they can also undergo personality and behavioral changes as a result. Spaying is seen as a healthy and practical solution to these issues, but will a spayed dog still go into heat? We spoke with Dr. Shagufta Mulla, a veterinarian with a DVM degree from Colorado State University with 20 years of experience as a small animal veterinarian, to learn more.

"In non-spayed dogs, each heat cycle will last an average of nine days, but it can range from three to 21 days," says Dr. Mulla. Spaying, or removing both the ovaries and the uterus of a female dog, should put an end to the dog's heat cycles. If a dog is spayed before her first heat cycle, she generally won't ever have one. The ovaries produce hormones, particularly estrogen, which prompt the heat cycles. With the ovaries removed, these hormones will no longer be produced, and the dog's heat cycles will come to an end. You should also see an end to your dog's heat-prompted behavioral issues and personality changes. Plus, this is the one sure way to prevent unwanted pregnancy.

Veterinarians don't recommend spaying dogs just because it ends their heat cycles. Both spay/neuter procedures have health benefits, especially if they are done before sexual maturity. Spaying has the added health benefits of reducing a pet's chance of developing mammary gland tumors, pyometra, and ovarian tumors. "Pyometra means that the dog's uterus is filled with pus," says Dr. Mulla. These three conditions can develop when a pet continuously produces estrogen. By removing the ovaries and stopping the estrogen production, the pet is likelier to live her life without developing these serious conditions.

‌Typically, spaying your dog will cause heat symptoms to go away.‌ But if your spayed dog is displaying symptoms such as swelling of the vulva or bloody discharge from the vulva, is attracting male dogs, and is showing submissive interaction with male dogs, there may be something else going on. It is possible that your female dog has a condition called ovarian remnant syndrome. "Swelling of he vulva is the earliest sign," says Dr. Mulla.

Ovarian remnant syndrome is caused when bits of ovarian tissue are left behind during the spay surgery. This tissue continues to release hormones, prompting a spayed dog to still go into heat every six to eight months. "Or potentially every 12 months for some giant dog breeds," notes Dr. Mulla. If your dog has ovarian remnant syndrome, you may not notice it right away since your dog's heat cycles may not begin until months or even years after the surgery has taken place. "Other possible causes of heatlike symptoms include estrogen therapy and uterine stump abscess, also called stump pyometra, or false pregnancy," says Dr. Mulla.

If you notice your dog displaying heat symptoms even though she's been spayed, you should schedule a veterinarian appointment to get to the bottom of the issue. They will diagnose the condition in any number of ways.

Vaginal cytology, which is a swab of your dog's vagina, will let your veterinarian test for cornified cells, a specific type of vaginal cell that in abundance identifies the presence of estrogen. "Dogs whose cytology show an abundance of a specific type of vaginal cell, callled cornified cells, are in heat," explains Dr. Mulla. Your veterinarian may also test your dog's hormone levels to look for abnormalities that identify that your dog still has ovarian function. If you can tell when your dog is in heat and get her into the veterinarian's office during that time, they can perform an ultrasound. Depending on the size of the ovarian tissue that is left, they may be able to see the tissue on the ultrasound.

In some cases, your veterinarian may need to perform exploratory surgery to determine if ovarian tissue is still present as well as to locate that tissue. They should be able to remove that tissue at the same time.

The treatment for ovarian remnant syndrome is, luckily, a pretty simple one. Should your dog be diagnosed with this condition, your veterinarian will need to perform surgery while your dog is in heat. "This is because the ovarian tissue will be active, meaning bigger, and more readily located," explains Dr. Mulla. Your veterinarian will remove any remaining ovarian tissue during the surgery. This will stop your dog from producing estrogen and will bring an end to her going into heat.

If you find that your dog has ovarian remnant syndrome and it is not treated, your dog will still be at an increased risk of developing conditions like mammary gland tumors, pyometra, and ovarian tumors. Be sure to speak with your veterinarian about any concerns you have regarding your dog's diagnosis or treatment.

Spaying your dog is an effective way to not only end the heat cycle but also prioritize pet health and prevent potentially serious health complications seen in unspayed female dogs, such as developing mammary gland tumors, uterine infections (more specifically, pyometra), and ovarian tumors. If you notice that your spayed female dog continues to experience signs of heat after being spayed, you should contact your veterinarian. This may be a sign that your dog is experiencing ovarian remnant syndrome, and surgery will be required to treat the condition.