Do Dogs Have Periods?

The bloody discharge associated with a dog’s heat cycle is not the same as a woman’s period.


Do female dogs have periods? No, dogs do not have periods. During one stage of the dog’s reproductive cycle there is a bloody vaginal discharge that superficially resembles a period. However, a dog’s heat cycle is not the same as a woman’s menstrual cycle. Dogs experience bloody vaginal discharge at the beginning of their reproductive cycle to increase fertility and prepare for pregnancy during the current cycle. If a woman does not become pregnant during one cycle, the uterine lining is shed at the end of the cycle to prepare a fresh uterine lining for the next reproductive cycle.

Signs of Heat in Dogs

When female dogs have a bloody vaginal discharge, they are considered “in heat” or “in season.” This is not a dog having a period. Signs of heat in female dogs include:

  • Swelling of the vulva
  • Bleeding from the vulva
  • Excessively licking the vulva
  • Possibly, tail tucked down tight

Dogs in heat may seem clingier than usual. Smaller dogs usually have their first heat around 6 to 7 months of age. Larger breeds often start a little later. Dogs usually come into heat twice a year, or every six months or so. The time to breed a dog is about one to three weeks after the bleeding starts (see stages, below).

Dog Heat Cycle Stages

There are four stages to a heat cycle:

  • Proestrus, which is when the bleeding starts, lasts one to three weeks, this is when inexperienced owners may start wondering if dogs have a period.
  • Estrus, which is when the dog is fertile and can be bred, the bleeding may slow or even stop and the female dog will be receptive to male attention, lasts one to three weeks
  • Diestrus, which is not a fertile time, if the dog is not pregnant it’s a quiet time in the cycle
  • Anestrous, which is the rebuilding time for the reproductive tract before the next heat cycle begins, lasts about four months

A dog’s heat cycle stages are not the same thing as a dog having a period. It signals the start of fertility for a female dog, and not the end of the cycle. If you’ve found yourself wondering if dogs have a period because your dog has started bleeding then you’ll need to take some precautions to avoid an unwanted pregnancy.

Avoid Unwanted Puppies

If your female dog goes into heat and you do not want her to get pregnant, keep close tabs on her. Never go outside without her on a leash, and be on the lookout for wandering, unattended male dogs when you do go outside. Watch her closely when she is outside in your fenced yard, too, as male dogs will jump fences to get to a female in heat. Help her keep her perivulvar area clean and dry. It’s OK to use diapers to limit the mess but change them frequently.

If you do not have plans to breed your female dog, consider having her spayed. This is the best way to avoid unwanted pregnancy and to prevent uterine and ovarian problems. And it will make your life a lot  easier, at least twice a year. Note: Dogs do sometimes have false pregnancies.