When Is a Female Dog Ovulating?

A female dog reaches sexual maturity between 4 and 24 months of age, depending on size and breed. Typically, a female goes into estrus, or "heat," twice a year, with each cycle lasting between two to three weeks. However, small breeds can have three to four cycles every year, while large breeds can have one cycle every 12 to 18 months. There are telltale signs that indicate when your female dog is ovulating, or in "heat."

  1. Vulva

    • Vulva swelling is the first sign your dog is ovulating, and it occurs during the first week of your dog's cycle. The vulva is located below the anus. The amount of swelling varies between dogs; some have little to no visible swelling while others have pronounced swelling. Your dog may also tuck her tail to protect her vulva. Other early signs of ovulation include licking her rear end and her teats may become more pink and prominent.

    Bleeding

    • The most noticeable sign your dog is ovulating is vaginal bleeding, or spotting, within a few days after she enters estrus. The bleeding may initially be light but become increasingly heavier and dark red. If you don't want your dog leaving spots everywhere, you can buy her doggie diapers or pads to wear while she's in heat. If you think her bleeding is heavier than normal, or if it doesn't slack off within a few days, you may want to take her to a veterinarian.

    Flagging

    • When your dog is ready to mate, she will stop tucking her tail and begin holding it out to the side. This is called flagging. She may try to mount a male dog and even bump her butt up against your leg. Her vaginal bleeding will slacken, becoming straw-colored, and her vulva will soften and return to normal. She may also begin urinating more frequently, leaving a scent trail rich in pheromones and hormones for males to follow.

    Tests

    • A veterinarian can tell you when your dog is ovulating. If you want to breed your dog, a veterinarian can do either a vaginal smear test or a simple blood test to determine when she is ready to mate. A vaginal smear test shows changes in both cellular appearance and numbers, while a simple blood test measures the level of progesterone in the blood. While the vaginal smear test is reliable, a blood test gives you a better idea of when mating is likely to be successful.