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When Does a Dog Become Sexually Active?


Do you think raising a puppy is hard?  Try raising a puppy that is pregnant with a litter of puppies herself!  What most pet owners are surprised to learn is that dogs can become sexually active and mature early in their lives.  Listed here is everything you wanted to know (or not) about your dog’s sexual health but were afraid to ask. 

When Does a Dog Become Sexually Active?

Dogs can become sexually active at a surprisingly young age, which is dependent upon their gender.

Female Dogs

Female dogs experience their first estrus at 4 – 6 months of age.  In general, small breed dogs reach puberty earlier, while larger dogs may not “come into season” until 2 years of age.  As dogs grow older their heat cycles may become irregular, but they will never stop ovulating entirely.  If heat cycles disappear, an underlying health issue is likely to blame. 

Male Dogs

Male dogs begin to experience puberty at 6 – 8 months of age but do not reach full sexual maturity until they are 12 – 18 months old.  However, male dogs can impregnate female dogs at the first signs of puberty.  Additionally, male dogs can impregnate females at any point throughout its life, even into old age. 

What Happens During a Heat Cycle?

When a female dog goes into estrus (also called “in heat” or “in season), she is able to reproduce.  For many dogs, this cycle occurs every six months.  However, small breed dogs may go into estrus more frequently, while giant breed dogs might only have one heat cycle per year. 

Estrus lasts approximately 2 – 3 weeks for most dogs.  The signs that a dog is in heat include:

  • Swollen external vulva
  • Bloody, vaginal discharge
  • Frequent urination
  • Marking behavior inside the home
  • Increase of male dogs marking nearby property

When a female dog is in heat, her urine will contain pheromones that attract male dogs.  Males can sense these pheromones from far away, and you may notice an increased number of dogs urinating on your property.  These dogs are simply trying to “claim” your property as their territory.

Approximately 7 – 10 days into your dog’s estrus cycle her vaginal discharge will become watery.  At this point, she is most fertile and most receptive to breeding.  However, a male dog’s sperm can survive in the reproductive tract up to 7 days, so a female dog can therefore become pregnant at any time once her heat cycle begins. 

What Can Be Done if My Dog Accidentally Mates with Another Dog?

Always talk to your veterinarian if you suspect your dog is pregnant.  If the dog’s pregnancy is unwanted, there are options available.  Not all veterinarians will perform a canine abortion, and many who do will only terminate pregnancies if the owner agrees to also spay the female dog. You may want to go ahead and read our article “Canine Pregnancy; Everything You Should Know!“.

At What Age Should a Dog Get Pregnant?

Although female dogs can become pregnant during their first heat cycle, responsible breeders typically wait until the third cycle before allowing the dog to breed.  Since most females experience puberty between 4 and 6 months of age, they are often too physically and mentally immature to survive pregnancy and raise healthy puppies.  In fact, kennel clubs have placed lower limits on the breeding age of dogs at 18 months for males and 14 months for females. 

How Often Can Dogs Mate?

Female dogs are physically able to procreate approximately once every six months, depending on breed.  However, breeding a dog for back to back cycles is controversial.  This practice may be bad for the health of the female dog, as pregnancy and nursing can be especially draining.  There are many factors to consider before allowing a dog to mate again, which should be discussed with a veterinarian.

 Gestation Period of a Female Dog

A dog’s gestation period (i.e. the number of days a dog is typically pregnant) is 58 – 68 days.  Therefore, it is easy to see how a pet overpopulation problem can occur.  If a dog can become pregnant as early as 4 months old and have 2 litters of 6 – 10 puppies per year, within 2 years one female dog and her progeny can potentially produce more than 220 puppies.

Why Do Male Dogs Hump?

Contrary to popular belief, humping is not purely a sexual behavior.  A male dog may hump for many reasons.  Of course, procreation is one cause.  However, a more common factor is dominance.  Both male and female dogs hump one another to assert their dominance over the other.  Dogs also hump humans to display dominance.

For other dogs, humping may be a sign of an un- or under-socialized dog.  For instance, when a dog that is unfamiliar with normal play becomes overly excited, he may hump other humans or animals. 

Preventing Canine Pregnancy

The only way to prevent an unwanted litter 100% is spay your dog.  Male dogs in your household should be neutered to prevent them from escaping and impregnating un-spayed females.  Female dogs should be spayed before their first heat cycle to reap the most health benefits.  Male dogs, depending on breed, can be neutered any time after 8 weeks of age.  However, giant breed dogs generally should not be neutered until 18 months of age. 

However if you plan on mating your dog at some point, you can use belly bands (our review) to stop your pup from doing his/her thing.

In addition to preventing pet overpopulation, spaying or neutering your dog can significantly reduce the risk of disease in your pet as well as minimize common behavioral problems.  Here is a whole list of reasons why you should spay and neuter you Dogs.


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Anna Weber

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