What age do dogs go on heat?


Are you a breeder planning for your next litter of puppies? Or maybe you’re a pet owner looking to avoid any unexpected little fur babies in your home? If you have a female dog who hasn’t been desexed yet, then it is important to understand the age at which your dog may go on heat and be aware of the signs when this does occur, which we will detail below. Having an insight into and information about this reproductive period can help you prepare and provide the best care for your dog, avoid or prepare for a new litter and keep clear of any dangerous situations caused by unpredictable behaviour during this time, whether from your own pet or other dogs.

What is Heat?

A female dog “on heat” is somewhat similar to a human menstrual cycle, however for dogs it is called the Canine Estrous Cycle, which consists of four stages.

  • Proestrus - first stage
  • Estrus - second stage
  • Diestrue - third stage
  • Anestrus - fourth and final stage

This cycle begins to occur when a dog reaches sexual maturity, with stage having its own signs and symptoms to be aware of. While you may think a female dog is only “on heat” or going through this cycle when she is passing a bloody discharge, the truth is this cycle is still occurring even once bleeding has stopped, which means a female dog is still fertile and able to have puppies when you may have thought she couldn’t.

What Age Do Females Dogs Go On Heat?

Generally, for female dogs that are not desexed, they will begin to experience this cycle once they reach puberty (sexual maturity) at around 6 months, however this can vary depending on the size and bread of the dog. For smaller breeds, this cycle may start from as early as 4 months and for larger and giant breeds, they may not experience going “on heat” until they are 2 years of age.

As long as they are not desexed, female dogs will experience this cycle, on average, every 6 months, though this can also vary depending on the size and breed of the dog. It can also take up to 12 months for their cycle to regulate. For smaller dog breeds, they may experience this cycle more frequently, up to four times a year. Larger and giant dog breeds may only experience this cycle every 12 to 18 months.

Unless a female dog is desexed, they will continue to experience these cycles throughout their life, though they may become less frequent as the dog ages.

For the majority of breeds, the timing of these cycles does not correspond to any season, meaning they can experience these cycles in summer, autumn, winter or spring. The Tibetan Mastiff and the Basenji are the only two breeds who’s cycles are known to correspond to seasons, with these breeds typically experiencing their cycle during spring.

At What Age do Male Dogs go on Heat

Male dogs do not go “on heat” but instead become capable of mating year round when they reach sexual maturity, which is generally once they reach 6 months.

The Four Stages of Your Dog’s Cycle

The Canine Estrous Cycle consists of four stages, with the whole cycle typically lasting around 2 to 4 weeks. During the first stage (Proestrus), your dog may begin exhibiting signs they are about to go through this cycle. Knowing and understanding the signs can help you to be prepared and help care for your dog’s needs during this time. In this first stage, the vulva (near the dog’s tail) can become swollen, but this isn’t always obvious and easy to spot. The first sign you may actually notice is that your dog begins to pass a bloody discharge, which may not happen until a few days after the first stage has begun. You may also notice your dog becomes clinger to you during this period and is more aggressive towards male dogs. This stage of the cycle generally lasts between 7 and 10 days.

During their cycle, female dogs should not be in any pain, they though may become a little fidgety and uncomfortable. If your dog does seem to be experiencing any pain during this cycle, consult your vet.

Females can also start to urinate more frequently during this time or start “marking”. Urinating in small amounts in various places either while on a walk or at home is her signal to male dogs that she is going “in heat”, as the urine contains hormones and pheromones that male dogs can detect from a great distance. Male dogs may also begin marking objects around your home in an attempt to claim their territory.

The second stage (Estrus) is when your dog is fertile and ready to mate; this is the stage that is most commonly referred to as being “in heat”. During this stage your dog’s aggression towards male dogs may decrease, however her aggression towards female dogs may increase. She may also continue to bleed during this time, however the discharge will become lighter in flow and colour. This stage generally lasts from 1.5 to 2 weeks, though sometimes it can be a little shorter or a little longer.

In the third stage (Diestrue), your dog may either be pregnant or no longer fertile. If your dog is not pregnant then during this stage discharge should stop and the swelling of her vulva will begin to decrease.

The final stage (Anestrus) is an inactive phase of the cycle and is essentially your dog’s downtime in between cycles, where their body gets ready for their next cycle. During this phase your dog’s behaviour should return to normal. This stage generally occurs 2 to 3 weeks from the last time you noticed discharge.

How To Prepare

If your female dog is going through heat she will be feeling hormonal, which can cause her to feel more stress and anxiety than normal, particularly if they are going through this cycle for the first time. There are a few things you can do to help keep her clean, safe and feeling as comfortable as possible during this time.

To reduce any stress or concern around mess caused by discharge, a great and comfortable option are pet nappies. A dog’s sensitivity can increase during this time, so providing extra blankets and bedding can help her feel more comfortable. This can also help contain mess if you prefer not to use pet nappies. It’s also a good idea to keep some wet wipes on hand, this will make cleaning up of any mess that does occur quick and easy. If you are still concerned about your dog bleeding in your home, limit the places they can roam during this time, blocking off any carpeted areas or rooms with upholstered furniture.

Ensure your dog has access to plenty of fresh, clean water, provide them with plenty of cuddles and even some extra mental simulation with soft and chew toys. This extra simulation combined with feeling safe and secure can help reduce your dog’s stress during this time.

Taking your dog on some extra walks can also help to further help relieve any stress or anxiety they may be feeling during this time. When you are walking your dog, be sure to keep her on the leash. Even if she usually has great obedience skills, this usual behaviour can change and disappear while she’s feeling hormonal during her cycle and you may find she ignores your calls to go off in search of a male dog.

Don’t scold your dog if mess does occur. These are accidents and your dog may already be feeling stressed if they are waking up and finding themselves in a messy state. Instead remain calm and provide cuddles and reassurance while you clean up.

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