Whether you are planning to breed your dog or whether you are trying to avoid a litter of unwanted puppies, you need to know if your dog is in heat. The heat cycle of every female dog can vary. If your dog does go into heat, document her behaviour and symptoms and record the number of days the heat lasts as well as the number of months in between heats. By doing this you will have a better idea of what to expect next time and when to expect it. Meanwhile, watch for the general signs of a female dog in heat.
An intact female dog will have her first heat before she is 1 year old. After that ,she will average a heat every six months. The heat cycle itself lasts an average of 21 days. The first part of the heat, proestrus, lasts up to 10 days. Next comes oestrus, which is about a week, followed by diestrus in the third week of her heat. Assuming she does not become pregnant, your dog will then return to anestrus, the resting stage that lasts five to 11 months.
In the first week of your dog's heat, she will not yet be ready to mate. Her personality may change, leaving her clingy and affectionate, or distant and grumpy. Her appetite may change as well. She may have an increase or a decrease in appetite. Her vulva will become swollen, and she will spend a lot of time licking it. She will begin to bleed, lightly at first, but then more heavily. The blood during proestrus will be a dark red colour. Male dogs will begin noticing her, but she will not be ready for them. She may tuck her tail or even sit down to keep other dogs from approaching her hind end.
The second week of her heat will have her ready to mate. Her vulva will soften as the swelling reduces enough to make her more easily penetrated. The blood flow will change from dark in colour to a lighter, salmon colour. She will begin urinating frequently to spread the word that she is ready to mate. She will also display a lot of tail wagging to spread her scent around and will be generally flirtatious towards male dogs, turning and offering her hind quarters to them. Some female dogs resist mating, but most female dogs welcome the male dog during oestrus.
During the third week of her heat cycle, your dog is no longer fertile. Her vulva returns to its previous state, and the bleeding slows and eventually stops. Your dog will no longer be receptive to male dogs. At this point she is either pregnant or she will return to the resting stage of her cycle.
If your dog is displaying symptoms of being in heat, you should be cautious about leaving her unattended in your yard. She may be inclined to break out, or another dog may decide to break in. Similarly, you may want to cease taking her for walks. Every time she squats to urinate during her walk, she will be leaving a breadcrumb for male dogs to follow back to your house. Whether you plan to mate her or not, you probably do not want a pack of amorous dogs on your front lawn. If you are not interested in breeding your dog, it is in your best interest as well as your dog's to have her spayed. You can have your dog spayed as a puppy before she even has her first heat. Not only will having her spayed let you rest assured she will not have any unwanted puppies, but also will it keep her healthier. Spayed female dogs have a lower instance of mammary cancer.