Before discussing pregnancy in dogs, it is important to stress that the breeding of pure-bred dogs is a serious endeavor best taken on only by responsible breeders, breeders who have studied all the intricacies of a particular breed of dog and are committed to maintaining and improving type, temperament and health. Knowledge of a breed’s official standard (that verbal description of how a breed should look, act and move) is only one part. Following recommended health checks for any -particular breed is also mandatory in the responsible breeding of dogs. These are the breeders whose aim is to produce dogs that will leave the breed in at least better shape than when they started breeding dogs.
How Long are Dogs in Heat?
Dogs are typically thought to be “in heat” for about 3 weeks. Depending on the breed and size of dog, puberty and the first heat cycle could occur anywhere from as early as 6 months of age until possibly over a year old. The smallest breeds will go into heat closer to 6 months, and the largest breeds may reach puberty until 1 year of age or possibly older. Once the first heat cycle occurs, they will generally occur every six months or so.
- The first phase of a heat cycle, proestrus, lasts an average of nine days, but can range from 3-17 days. You will notice bloody vaginal discharge and her vulva will appear swollen. Male dogs will become interested in females, but she will not be receptive to them.
- The next phase is called estrus. This stage also lasts an average of nine days but can vary from 3-21 days. Estrogen levels will peak and then fall before she ovulates. The bleeding will diminish, and the discharge will appear lighter and less bloody in appearance. You may also notice her urinating more, marking many spots when she goes for walks. She will usually “flag” or move her tail to one side when touched near her vulva. Pheromones in her urine attract male dogs.
- This is the phase where a female dog can become pregnant if she is bred. If a dog had been bred, she will deliver puppies approximately 63 days after breeding.
- Diestrus follows her fertile period and lasts for about two months. Her levels of estrogen will decrease, and her progesterone levels first increase and then decrease. The fourth phase, anestrus, will follow and for the next four months or so, her hormone levels are low and her uterus is recovering until the next cycle begins.
There is no menopause in dogs. Older female dogs continue to have heat cycles, but they become further apart and her fertility tends to decrease. However, there have been reports of dogs becoming pregnant as old as 16 years of age.
Spaying your Dogs
Spaying is the surgical removal of a female dog’s ovaries and uterus. There is a lot to consider regarding the best age and time to have your dog spayed. Your veterinarian is your best source of information to help you weigh the pros and cons of this important surgical decision. Hormonal effects are known to impact the health of all animals including dogs and recent studies suggest that in certain breeds, there has been a link of increased incidence of certain orthopedic and soft tissue conditions as well as an increase in certain cancers associated with spaying too early in life, with the exception being mammary cancer.
Unless there are temperament or necessary population control issues, it might be preferable to wait to spay a dog until at least 4-6 months of age in small breeds or slightly later in the larger breeds, when she has nearly reached full maturity.