Now that your homework is done, you need to wait until your bitch is ready to breed, or until she is “in heat” or “in season.” The first heat usually occurs when she is between six and fourteen months of age. Most bitches cycle roughly two times a year, but each is an individual. Some only cycle once yearly or even every eighteen months. A few bitches cycle every four months. Once again, the breeder of your bitch is an invaluable source of information. Most bitches will follow the cycle of their dam.

Stage One

There are four stages in a bitch's reproductive cycle. The first stage proestrus. This stage, which lasts about nine days, is when the pituitary starts producing hormones that influence reproduction, such as follicle stimulating hormone (FSH) and luteinizing hormone (LH). The FSH causes the follicles (capsules around the ovum or egg) to increase in size so the ovum can develop, and the LH helps the ovum to mature. The vulva will start to swell, and your bitch may have a bloody discharge. Be aware that some bitches are so fastidious they clean all the blood up right away, so you may not notice drops on the floor. If you think your bitch may be coming into heat, you might want to do the “white Kleenex test” every morning. Take a clean white tissue and gently touch the vulva to see if you find any blood droplets.

Stage Two

The second stage, also usually about nine days in length, is estrus. This is the time of peak conception rates and when your bitch is most likely to accept the male. The cells in her vagina will change, and her progesterone levels will rise. Once progesterone levels peak, your bitch will ovulate two days later. Now is the time to breed!

Knowledgeable breeders and veterinarians work together, checking progesterone levels and looking at vaginal cells under the microscope to determine the best dates to breed. Ideally your bitch will be bred at least twice during this time of maximum fertility.

Stage Three

Unless she has become pregnant, your bitch's reproductive system will switch over to diestrus about six days after ovulating. The progesterone level will drop again. Due to the hormone fluctuations, this is the time she is most prone to develop uterine infections (known as pyometras) if she isn't bred. This stage lasts about two months, the time it takes for your bitch to whelp her litter (give birth) or for her hormone level to fade.

Stage Four

After diestrus, the bitch's reproductive tract goes into a resting stage called anestrus. During this time, the body replenishes itself and prepares for another round of possible reproductive activity. This stage is the most variable of the reproductive stages and can last four months or more.