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How Long Are Dogs in Heat? Dogs' Estrus Cycle | BetterVet

Coming into heat, being in season, or estrus are all ways of saying your dog is in the fertile window for breeding and how long are dogs in heat often depends on their breed.

Owning a female dog means you could end up with a litter of puppies if you are unaware of your dog’s breeding cycle. All female dogs have the potential to become pregnant from as young as six months of age. This doesn’t leave owners a lot of time to prepare or plan, especially if you are a first-time dog owner trying to master the basics for everything else! 

What age does a dog come into heat? 

It varies with breed. Small and miniature breeds tend to come into heat around 6 months of age. Large and giant breeds may have their first heat between one and two years of age. There is no set timing or season of the year when dogs come into heat. Usually, after the first cycle, dogs will have around two heats a year, six months apart, for the rest of their lives. 

The first few heats may not quite fit this time period exactly and large or giant breeds may only come into season once a year. After owning your dog for around 2-3 years, you should notice a familiar pattern to her seasons that can help you to prevent pregnancy. 

Dogs continue to come into heat for the rest of their lives, and can be bred at an older age, although this does come with increased risks for the mother and puppies. The best age to breed your dog is between two and five years of age, and between one and three litters are recommended. 

How long are dogs in heat? 

Your dog will be in heat for around one and a half to two weeks, varying between individuals. A veterinarian can perform blood tests to tell you when ovulation has occurred. This can help you to manage breeding dates for increased chances of success. 

What are the signs of being in heat? 

The first sign you may notice is your dog’s vulva becoming swollen or enlarged. She will then progress to bleeding. This is completely normal, and the blood can range from a thick, dark brown color to light, watery pink. Every dog is different, some dogs will have heavy spotting and others can be quite light. It can be a messy time for your home. Using pet-safe cleaners to remove any spotting is important when you have a female in heat. 

Bitches in season will urine mark. You may notice that your dog is urinating little and often either around the home or on a walk. Urine marking lets male dogs in the area know that there is a female on heat. Male dogs can smell the pheromones released in the urine from long distances away. 

It’s not uncommon for females in season to have a reduced appetite, or to see behavioral changes like wanting more attention or becoming reclusive. This is hormone related and she will go back to normal after her heat is finished. 

Preventing unwanted pregnancies 

Most dogs are bought as a family pet and we may have no intention of ever breeding them. As we learn more about the link between hormones and joint closures in large and giant breeds, the recommendations for the best time to spay your dog has changed. A miniature to medium-size dog can still be spayed before their first heat at around 5- 6 months. For large to giant breed dogs, the recommendations have changed to spay between one and two years old. So, if you have a large or giant breed dog, you may need to prepare to protect your dog against accidental matings. 

For the one to two weeks your dog is in heat, do not walk your dog outside of your property if possible. If you must exercise her, keep her on a lead, and go very early in the morning or late at night to reduce the chances of bumping into dogs who may show interest. Drive to a different location away from your home so that male dogs cannot follow her scent back to your home. When at home, make sure all the garden gates, house doors, and windows are securely locked and keep her inside if possible. Putting ‘period panties’ on your dog will not prevent accidental mating, although may help reduce the mess from spotting. 

Frequently Asked Questions


How can I stop my dog from coming in heat? 

Surgical sterilization, also known as a spay procedure, is the most effective way to stop your dog from coming into heat. This is an operation that removes the ovaries and uterus, so your dog can never become pregnant. 

Do female dogs go through menopause?

Older female dogs do not go through menopause as humans do. They will continue to come into heat, but you may notice the intervals between their heat are longer or more unpredictable. 

Help, my dog was accidentally mated! 

There are injections that can be given by a veterinarian to terminate an unwanted pregnancy. Two injections must be given 24 hours apart and can terminate a pregnancy up to 45 days. 

How long is a dog pregnant? 

Dog pregnancies are fairly short compared to humans; the average gestation is 60-65 days. Your veterinarian can confirm pregnancy with ultrasound from as early as 21 days or x-rays after 45 days post-mating. 


It varies how long dogs are in heat, but all dogs do experience a heat. If your dog reaches 3 years old and hasn’t had a heat yet and you are wanting to breed, you should reach out to a veterinarian for advice.  

A dog in heat is a completely natural process, although for the new dog owner it can be a bit overwhelming and messy. The easiest way to prevent stress for you, and unwanted pregnancies for your dog, is to spay her. Not only does this take away her ability to breed, but protects her against other harmful conditions like uterine infections and cancer, which can both be life threatening and very expensive to treat.