A bitch generally has her first estrus season, or heat, at between 6 and 12 months of age, most commonly between 8 and 10 months. Mating will produce a litter at this age, but she is immature, so it is important to guard against that potential. A female dog will normally return to season about every six months. Some have estrus seasons as often as every four months or less. If you are not a serious breeder, the healthiest thing you can do for your female puppy is to spay her before she reaches sexual maturity, according to the PetMD website. If you do not spay her, you must provide special care for her for the better part of a month, two or three times per year.
Watch for early signs that your dog is coming into heat. A heat period lasts about 21 days. During the first 11 or so days, the proestrus, the female will first display a blood-red discharge that may not initially be highly noticeable, and you may miss it if you are not watching for it. The discharge gradually turns pinkish and then cream-colored. The female will attract males, but will not accept them for breeding during proestrus.
Keep your dog in heat safely confined in the house. Crate her if possible; stray male dogs likely will be hanging around the house. Don't leave your bitch out in the yard. Male dogs will go to great lengths to access a female in season. When your female must go outside, keep her on leash.
Apply dog panties to your dog in heat to protect household surfaces from blood. The amount and color of the discharge will decrease with each successive day. While proestrus generally lasts for about 11 days, it can range from eight to 13. The female will typically not accept a male during this time, but when proestrus ends, she will.
Keep your bitch even more carefully confined in the estrus phase itself, which generally occurs around day 10 or 11 and continues to about day 18. This is the standing heat phase of the cycle, in which the female will be receptive to breeding. Note that the vulva is swollen but is not rigid. Discharge is not obvious and is straw-colored. You must be alert to these signs, because they can occur much earlier than the average 11 days in some females, and later in others. If your female dog is accidentally bred, you may assume with virtual certainty that she will be giving birth about two months later.
Continue your vigilance after the 18th day until you are absolutely certain your female is out of standing heat and will repel any male advances. The 18th day is the average time at which this occurs, but it varies considerably.
Consider spaying your female dog after her first heat. You will eliminate the two or three months per year of vigilance and hassle, and you can virtually eliminate many potential health problems for your pet, such as mammary tumors and uterine infections. You and your pet will be far more carefree, and you will also avoid contributing to the tragedy of pet overpopulation.