Female dogs will start to show signs of estrus between seven months to around a year old and owners will notice different types of dog behavior during this cycle. A female of a small or medium sized breed tends to come into heat (estrus), younger than a female of a large or giant breed, although there are individual differences. Regardless of the exact month the female will first come into heat, it is important for owners to understand the changes in dog behavior they will see and plan how to handle the situation.

Stages of Estrus

There are three distinct phases or stages to dog behavior during the estrus cycle. Females will come into heat one or two times per year, often in the spring and in the late summer or fall, however each individual dog will have her own cycle. The different stages may bring about more aggression, more submission and more abnormal behaviors, especially if owners are not aware of what is going on. The general female dog behaviors that are noted in the three stages include:

• Proestrus
  Literally the pre-estrus stage. This can last from a few days to up to two weeks. During this stage the female will engage in dog behaviors that include frequent urination, licking of the genitals, clear discharge then a somewhat bloody discharge, increased need for attention and increased attention in other dogs, both male and female. If other intact females are in the same area, your female dog may begin to be more aggressive towards the females but more playful towards neutered or intact males. Some females become very submissive in this stage and may need to be isolated from other more aggressive females and males.
• Estrus
  This is the stage where the female dog behavior will often become the most dramatic in its differences. She will be more aggressive towards females and possibly even males that are trying to mount her. There will be a stop to the discharge, however the vulva will remain swollen and she will continue to lick the area. During this time the female is actively trying to be bred so she will attempt to escape, become very excited around male dogs and present herself for breeding to males that she is interested in. She may become slightly more aggressive towards her owners, particularly over grooming, possessions and food. Generally children should not be left unsupervised with females in this stage, which lasts up to 8 days, as she is more likely to snap or become possessive. If males are present they may also respond much more aggressively at this time.
• Diestrus
  The last actual stage of the estrus cycle, this is where the female adjusts either to a pregnancy or to the fact she is not pregnant. Even a female that has not been bred may exhibit the same dog behavior as a pregnant female including swollen milk glands and nipples, depressed behavior and even "nesting" with her toys. She may need lots of attention or may want to be by herself more than usual. This is called false pregnancy and you should have her checked by the vet if she becomes despondent or there are any dramatic changes from her normal dog behavior.

Finally, after 6-10 weeks the diestrus stage will be over. At this point her hormonal system basically shuts down for about 4 months or more, after which she will enter into proestrus again.

Talk to other owners, breeders and your vet or do some research to prepare yourself for the changes you will see in your female as she matures. If you want to avoid dealing with these issues and help your female stay healthy, have her spayed prior to her first estrus cycle. Most vets recommend spaying anytime after six months of age. Keep in mind that female dog behavior in estrus is like any other type of dog behavior, it will be expressed differently between each dog and each breed.