Can You Spay A Dog In Heat? What Are The Dangers And What Should You Do?

Oh no – can you spay a dog while she is in heat? Ugggh!!!

It’s one of those timing things that has happened to many of us! Your young bitch is due to be spayed….and what do you know? She goes on heat! Read on to learn why spaying a dog on heat is far more involved and potentially dangerous.Can you spay a dog in heat?

Can You Spay A Dog On Heat?

Yes, veterinarians can spay dogs in heat. However, there is more risk of complications when spaying a bitch who is in the middle of her heat cycle meaning that not all veterinarians will be comfortable performing this procedure.

A veterinarian will need to consider the following before making their decision:

1. Age of the bitch

2. Body condition – is the bitch overweight?

3. Any concurrent illnesses that may contribute to an increased risk eg. anaemia

4. Their own surgery skill and that of their assistants.

Be prepared to hear your vet say “no”.

If your vet is unable to perform the spaying procedure your options include:

  • find another vet to perform the surgery,
  • wait a couple of weeks: keep your bitch locked up inside at home or send her to a kennel facility for the duration of her active heat cycle

You must not leave your girl outside unattended. Intact males have been known to dig and jump huge distances to get to a bitch in season.

Ultimately, the decision to spay your in heat bitch lies with both you and the veterinary surgeon who will perform the surgery.

What Are The Dangers Of Spaying My Dog In Heat?

The spay surgery (or ovariohysterectomy: meaning the ovaries, the fallopian tubes and the uterus are all removed) is one of the most difficult surgeries your veterinarian will perform.

It may be routine, but it certainly isn’t easy.

A dog spay surgery is the equivalent of a female hysterectomy.

When a bitch is actively cycling the tissues are swollen and ooze blood surgery time is often prolonged.

Blood vessels are engorged.

Bleeding tends to occur more frequently.

Tissues tend to be more friable (fragile) so knots may pull through resulting in internal bleeding.

It can be a stressful surgery made worse in large breed dogs, those with a deep chest and overweight dogs.

Because of the increased surgery time and difficulty, the majority of veterinarians will charge more for spaying bitches that are in heat.

How To Decide If I Should Spay My In Season Bitch?

You really need to ask yourself these questions:

1. What is the risk of the dog becoming pregnant?

This may be the most important question. If the risk of the dog becoming pregnant is high then it is better to spay the dog while it is in heat.

2. Can I handle the signs of heat?

This not only includes having to clean up spots of blood, but occasionally females in heat will show a negative change in behaviour such as being snappy.

How significant are these nuisances to you and your family?

3. Can I keep a bitch in oestrus away from intact male dogs?

Most importantly, can you keep your bitch away from males so that no unwanted pregnancy can occur?

She will need to be kept inside or in a fully enclosed dog kennel.

Remember: the fertile period of the oestrus cycle of the bitch can last from hours to many days. On average it lasts 4 days.

How Old Are Bitches When They Have Their First Heat?

Female dogs will become sexually mature and have their first heat or season around the age of six months for small breeds and up to 24months for larger breeds.

Many veterinarians will recommend that you spay your bitch around six months of age.

However, there is new evidence that shows for some breeds, delayed spaying may be beneficial and protective against some cancers, bone and joint disease and urinary continence.

Take a look at our article on the best age to desex your dog or talk to our vets for specific advice.

What Are The Signs of Oestrus?

When a bitch is in heat (oestrus) the following signs occur:


Proestrus in the bitch averages around 9 days in duration, but may last anywhere from 3 to 17 days.

Males will show interest in the female, but females are not interested in males. So generally no mating occurs.  The bitch can be quite nasty towards males who show them attention.

During this time the vulva is swollen due to the influence of oestrogen secreted by developing follicles.

Serosanguinous (blood-tinged) fluid is discharged from the vulva.


Oestrus averages 9 days in duration but can be as short as 3 days or as long as 21 days.

The male and female are both interested in each other and mating can occur.

The bitch will ‘flag’ her tail, and will often ‘back up’ to the male, asking for attention.


While not all dogs have the same length of heat cycle, most last on average 3 weeks.


How Long After A dog Is In Heat Can You Spay Them?

Due to the increased complexity of performing surgery whilst a bitch is in oestrus, many vets ask that you wait and rebook surgery.

The time it takes for blood vessels and tissues to regain their pre-cycle state can vary, but most vets will advise waiting at least 8 weeks.


Written by Dr Leigh Davidson BVSc, BApplSc

Further Reading

Why Should I Desex (Spay/Neuter) My Dog?

The Whelping Bitch – signs, stages and when to call the vet!

PUPPY VACCINATIONS: What Vaccines Do They Need And When?