when your puppy becomes a dog in heat

Is your girl puppy suddenly a female in heat?

“Heat” is the start of a female dog’s reproductive cycle. So, if your puppy is female, be prepared — girl dogs start their reproductive cycle when they’re anywhere from 6 months to a year old. If you’re looking to stop things before they start, talk to your veterinary team about spaying your pup before their first heat. If you’re interested in breeding your pup, here’s what you need to know.

Look for the signs of the estrus cycle starting around 6 months of age

Starting when your female puppy is between six months and one year old, she’ll begin her reproductive cycle, or “go into heat.” During this 3- to 4-week period, she’s ready to mate and looking for dates. That said, every pup is different and your pup may be on her own timeline. Interestingly, smaller pups tend to have their first heat cycle earlier than larger-breed pups.

The three stages of the canine heat cycle

Your puppy’s heat cycle has three phases: proestrus, estrus, and diestrus. Each stage is important to understand if you’re looking to breed.

Proestrus often shows as a swollen vulva

In this first stage of heat, your puppy’s vulva will look swollen or larger than usual. During proestrus, she’ll also produce a bloody vaginal discharge and may pee more often. Things change mentally too. She may show differences in behavior, like being more jumpy or on edge than usual. She may even be a little more clingy toward you (which is honestly just cute...mostly).

The estrus phase is when females are fertile

Once your dog enters estrus, she’s ready to mate. If you’re interested in breeding, estrus is the time to contact your veterinary team so they can conduct a few tests and determine the best time for your pup.

During estrus, your dog’s vaginal discharge will change to a clear or brownish color. She’ll move her tail to the side to indicate to males that she’s available, a behavior called “flagging.” She’ll also radiate pheromones that will catch the attention of dogs for miles around. Male dogs will become interested in her, while other female dogs may act aggressively toward her — and she may return the favor.

If you don’t want your girl dog mating, it’s important to keep her away from males during estrus. Fair warning that this may be easier said than done.

Diestrus is the end of the heat period

Diestrus marks the end of the vaginal discharges until the next heat. Your puppy’s vulva will go back to its normal size, and her interest in mating and dating will be all but gone. Sometimes, though, a pup will act as though she’s pregnant when she’s actually not. If you think your dog is pregnant (or if you think your pup thinks she’s pregnant) make an appointment to check things out.

What’s nextrus?

Spaying is your best bet to avoid pet pregnancy and the whole heat cycle. While it’s preferable to spay a pup before their first heat, you can always talk to your Banfield veterinary team about the appropriate plan of action for you and your pup. See more about spaying and neutering