Bitches will have their first reproductive cycle at puberty. Each cycle consists of several stages; a stage called estrus refers to the time when a female can become pregnant. It is often said that a calf in the estrus phase is in “estrus” or “in season”.”
Signs of a dog in estrus
There are a few obvious signs that the dog has estrus:
Your vulva will get bigger, although it is not always very visible.
Bloody vaginal release can be observed at the beginning of the estrus cycle in your dog. Within a few days, the release will become watery and pinkish.
You may notice that your dog urinates more often than usual and that spotted signs appear on it. This is done to attract partners and let them know that you have estrus.
He may also seem more alert or nervous than usual, and the males will have the impression of lifting the rump or pulling the tail to the side.
When does the heat start?
Estrus cycles in dogs begin at puberty, which can range from 6 months to 2 years, depending on the size of the breed. Small dogs reach sexual maturity earlier than large dogs. How often a dog starts estrus also depends on its size. Dogs will have between 1 and 3 cycles per year, and most dogs will cycle twice a year (in smaller dogs, estrus occurs more often than in larger dogs). On average, a dog will have estrus for 2 to 4 weeks. You are most prolific when the vaginal release turns pink and watery, although you can get pregnant at any time during your menstrual cycle.
What are the four stages of the estrus cycle in dogs?
The four phases of your dog’s estrus cycle are estrus, estrus, right circulation and anestrus.
Prostro
The proestrus is the first part of the estrus period when your dog’s body is preparing to mate. This phase usually lasts about 9 days. Your vulva will swell and you may notice a release with a bloody tinge. Your dog may also keep his tail close to his body and behave with more affection for you than usual. At this stage of the estrus cycle, your dog will begin to attract males, but will not be receptive to them and may growl or bite if they try to ride him.
Rut
Estrus is a mating phase that usually lasts about nine days. During this time, his release will become less bloody. Bitches will attract and accept males and ovulate two to three days after mating. Your furry little one is more likely to stain urine stains at home or outdoors. This sends a message that it is ready for playback. If there is an uncastrated male nearby, your dog will probably approach him for mating.
The right hand
This phase occurs immediately after the estrus stage and lasts about two months. Your dog’s body will be pregnant or will return to rest. Your vulva will return to its normal size and the vaginal release will disappear.
Anastos
The anestrus is the recovery phase of the uterus. No sexual or hormonal behavior is observed during this period. This phase can last from 90 to 150 days before the start of the next proestro phase.
How to prevent estrus in your dog
Most pet owners (with the exception of dog breeders) decide to sterilize their bitches before their first estrus. Some experts believe that this reduces the risk of breast cancer and other health-issue. It also eliminates the possibility that unwanted litters of puppies will have to be placed in shelters or euthanized. Sterilizing your dog is the only way to make sure she doesn’t get pregnant.
Tips for working with a dog in heat
If this is your first rodeo with an unsterilized dog, you may not know what to do when your dog has estrus. These simple tips will help simplify the process for you and your cute puppy.

Even after your dog has stopped bleeding, she can still get pregnant. She is much more likely to allow the male to mate after the cessation of bloody secretions.