Estrous Cycles in Dogs

When does a female dog have her first estrous cycle?

Female dogs have their first estrous (reproductive or heat) cycle when they reach puberty (sexual maturity). On average, puberty occurs in dogs at about six months of age, but this can vary by breed. Smaller breeds tend to have their first estrous cycle at an earlier age, while large and giant breeds may not come into heat for the first time until they reach 18 months to two years of age.

The estrous cycle is better known as a dog’s heat cycle. Each cycle consists of several stages; the stage called estrus refers to when the female is sexually receptive. Often, a dog that is in the estrus stage is said to be in heat or in season.

How often does a female dog come into heat?

Most dogs come into heat twice per year, although the interval can vary between breeds and from dog to dog. Small-breed dogs may cycle three times per year, while giant-breed dogs may only cycle once per year. When young dogs first begin to cycle, it is normal for their cycles to be somewhat irregular. It can take up to two years for a female dog to develop regular cycles. There is no set breeding season for domesticated dogs, except for basenjis and sled dog breeds, which typically cycle in the spring.

What are the signs of estrus?

The earliest sign of estrus is swelling or engorgement of the vulva, but this swelling is not always obvious. Bloody vaginal discharge is often the first sign that an owner notices when their dog comes into heat. In some cases, the discharge is not apparent until several days after estrus has begun. The amount of discharge varies from dog to dog. The vaginal discharge will change in color and appearance as the cycle progresses. At first, the discharge is very bloody, but as the days pass, it thins to become watery and pink in color.

A female dog in heat often urinates more frequently than normal or may urinate small amounts on various objects to mark them, either in the home or when out on a walk. During this phase of her cycle, the urine contains pheromones and hormones, both of which signal her reproductive state to other dogs, and can attract male dogs. Male dogs can detect a female in heat from a great distance and may attempt to claim their territory by marking it with urine.

How long does estrus last?

Each heat (the time during which the dog is receptive to males) generally lasts 9 days, although it can range between 2 and 24 days, and can vary by individual.

At what stage of the estrus cycle can the dog get pregnant?

A female dog usually ovulates around the time when the vaginal discharge becomes watery; this marks her most fertile stage and is the time when she is most receptive to breeding. However, she can get pregnant at any point while she is in estrus, as sperm can survive for a week in the reproductive tract and still fertilize the eggs. Contrary to popular belief, a female dog can still get pregnant even if she and the male dog don’t “tie” (get stuck while mating) after mating.

How long does pregnancy last in a dog?

Pregnancy in dogs lasts approximately nine weeks (63 days).

How can I prevent my dog from becoming pregnant?

The best way to prevent your dog from becoming pregnant is to have her surgically sterilized (spayed) by ovariohysterectomy or ovariectomy before she has her first estrous cycle. It can be difficult to predict when this first cycle will occur, so most veterinarians recommend performing the procedure before the dog is six or seven months of age.

What can I do if my dog has been mis-mated or accidentally mates with another dog?

If your dog has been mis-mated or accidentally mates with another dog, contact your veterinarian as soon as possible. They may recommend medication to try to terminate the pregnancy, but there are associated risks and regular checkups are essential. Your veterinarian will discuss your options and any risks associated with them.

Should I let my dog have an estrus cycle or a litter of puppies before spaying her?

There are no valid reasons for letting a dog have a litter of puppies before she is spayed. Some larger dog breeds may benefit medically from delaying their spay surgery until after their first estrus cycle (e.g., Labrador retrievers, golden retrievers, and German shepherds); however, the consensus is that spaying will generally increase the lifespan of a dog, regardless of timing. Dogs can become pregnant on their very first estrous cycle, increasing the risk of accidental breeding. Dogs are indiscriminate, so a brother may breed with his sister, a father may breed with his daughter, and a son may breed with his mother.

A common belief is that female dogs become more friendly and sociable if they have a litter of puppies. This belief is not true and only contributes further to the serious problem of dog overpopulation.