How old can a dog have puppies?

Do you have a puppy, or a dog that is about to enter its first heat and you want to know when the animal can reproduce? Is the first heat a good age for dogs to have puppies? To answer these questions, this post will talk about the reproductive cycle of dogs and what care should be taken before breeding dogs.

How old can a dog have puppies?

Puberty in the dog happens around 4 months of age and can extend up to 12 months. Several factors can influence the dog’s puberty, such as temperature, diet, presence of other animals and others. It is at puberty that sex hormones play a role in maturing the body and preparing the animal for reproduction.

But can I put my dog to breed in the first heat? The animal can even reproduce in the first heat, which can happen from 6 to 18 months of dog’s age; however it is not recommended to reproduce at this stage of the animals’ life. In the first heat, the animal is still developing, so it may present a risky pregnancy.

Therefore, it is recommended for a female dog to have puppies after her second heat, that is, between one and two years of age. The males, on the other hand, ideally should also reproduce after one year of age, even though the pups are already producing sperm at puberty.

Due to the wide variation of breeds and sizes, the dogs reproductive age can vary. This wide age range makes it necessary to consult a veterinarian before breeding a young dog. The veterinarian will better guide the tutor about the best age to breed their dogs according to the specific characteristics of the animal evaluated.

The estrous cycle in female dogs

It will be in the first heat that the animal will be influenced by hormone peaks and the wide variation of reproduction hormones, which will be responsible for finishing the animals’ development. The reproductive cycle in dogs is known as the estrous cycle and can be divided into 4 phases:

  • Proestrus;
  • Estrus;
  • Diestrus;
  • Anestrus.


In proestrus, the female canine body is preparing for ovulation and pregnancy. In this phase, hormones make the females have vulvar swelling, bleeding and become more attractive to males. However, at this stage the female still does not accept the male’s copulation.

It is the phase of the “dating” of the dogs, it involves games of attraction between the dogs. Female dogs can be more agitated during this period and even run away. It is important to beware of unwanted leaks.


Estrus, also known as heat, is the period in which the female accepts the male dog’s copulation. It is at this stage that ovulation of the female dog takes place. So only copulations in this period will make the female dogs get pregnant. Estrus can be shorter in some animals as well as longer in others, ranging from 7 to 21 days on average.

In female dogs, the vulva remains swollen, but the bleeding may stop. Care must be taken, as many owners think that the heat is over because the dog has stopped bleeding. But many times, she is just going through her most fertile period.


The diestrus is the phase in which the uterus prepares to receive the embryos; it lasts from 58 to 68 days. Female dogs reduce vulvar edema, and may present translucent secretion in the vulvar region. It is at this stage that many bacteria can develop in the uterus of female dogs resulting in pyometra. And when female dogs reproduce in estrus, diestrus becomes the fetal developmental stage of pregnancy.


Anestrus is the longest phase, lasting up to 4 months in some animals. In this phase, hormonal quiescence occurs in female dogs. Normally at this stage, female dogs do not accept the mount, much less the male’s copulation, and thus can be quite aggressive. The vulva returns to its normal size which makes copulation even more difficult.

Pre- pregnancy care for females’ dogs

Breeding dogs should always be accompanied by a veterinarian. Only healthy and adult dogs should be bred, so blood tests and tests for sexually transmitted diseases in dogs should be done.

Healthy female dogs must be vaccinated before mating and a deworming protocol must be carried out to avoid contamination of puppies intrauterine or after birth.

Some female dogs can become very aggressive with males when the correct time for breeding dogs is not respected. Many times, animals can end up injured. 

Also, it is not advised to leave the male and female together during the entire time of estrus. Because dogs can spend hours trying to copulate, thus stressing each other. In addition to having the possibility of getting hurt from trying so hard to copulate.

Some animals should receive vitamin supplements before and in the first days of pregnancy to avoid malformation problems in dogs. Female dogs must be at the ideal weight for the species, it is not desirable for obese or very thin females to breed. The diet of the pregnant dog can also change, so that the animal does not lose so much weight at the end of pregnancy.

It is also important to have a reserve of money for the veterinarian to carry out exams and pre-delivery follow-up, as well as money to cover the costs of medical emergencies.


Dogs should not be bred in their first heat. It is important that dogs have an appointment with the veterinarian before they are bred. Only the veterinarian will tell you the best age for a dog to breed. In addition, the tutor can be guided on what is necessary to avoid pregnancy losses in dogs.

Frequently Asked Questions (FAQs): How old can a dog have puppies?

Is it possible to manipulate a female dog’s estrus with drugs, as in cows?

Yes, it is possible, but it is not so used because many female dogs also do not respond to hormonal protocols, so few animals go into heat. Therefore, it is recommended to let the animal come into heat naturally and the tutor will be accompanied until the exact moment of reproduction.

How long does pregnancy last in female dogs?

On average, the duration of pregnancy in female dogs is 63 days, ranging from 58 to 68 days from the day of mating. Veterinarians can dose hormones that will give a more accurate date for parturition. In addition, there are imaging tests that can indicate approximate parturition dates in female dogs.

Can female dogs have more than one heat per year?

Yes, some dog’s breeds can come into heat every 4 months. However, care should be taken as constant repetitions of heat can be a sign of endocrine diseases, so a veterinarian should be consulted to avoid health problems in dogs.


Concannon, P. W. (1993). Biology of gonadotrophin secretion in adult and prepubertal female dogs. Journal of reproduction and fertility. Supplement, 47, 3-27.

de Souza Teixeira, E. (2001). Princípios básicos para a criação de cães. NBL Editora.