Can a dog get pregnant while bleeding during the heat?

Can a dog get pregnant while bleeding? There is a widespread belief that a dog can’t get pregnant during the first days of her heat cycle. Many our patients with their first female dog are confused by their dog’s heat cycle. This article is about your female puppy and the risks at the start of her heat cycle.

Female french bulldog looking at you with her head tilted — Your little girl’s heat cycle is different than a human’s menstrual cycle

When can dogs get pregnant?
Why your dog can get pregnant while bleeding
How do I know if my dog is in heat?
For more information

When can dogs get pregnant?

The first misunderstanding about the dog heat cycle is the “beginning”. It’s very common to assume that the first days of your dogs estrous cycle is that it’s just starting and there’s no need to worry. The reason is that we like to compare your dog’s estrous cycle of female dogs to menstruation in humans. However, it’s a very different thing. We’ll get to the differences in a bit.

Please understand this key point. Your female dog can become pregnant while bleeding. Even if breeding occurred on the first day of her heat. Before we go any further, we understand there are reasons for to not spay your female dog. You may want to breed her, you are waiting until she is old enough, etc. For reference on when to breed your female dog, here are the guidelines we use and they are consistent with the AAHA recommendations. In larger breeds (over 45 pounds for example), we recommend waiting until they are grown up enough. For smaller dogs, we recommend to spay at 6 months or just prior to their first heat. Please work with your vet on the best timing for spay surgery. Okay, off of our spay/neuter soapbox.

Why your dog can get pregnant while bleeding

Here are the key reasons:

Red (bloody) vaginal discharge of a dog’s heat cycle is not the same as menstruation in women. Human menstruation means that the ova did not get fertilized and is now being flushed from the body. This process happens right after the fertile days and a woman cannot get pregnant during this time. However, so-called “bleeding” in dogs is not the same thing. The bleeding happens before, not after the fertile days. This means, when your female puppy is bleeding, you have to become careful to avoid unwanted dog pregnancy. In other words, keep your female dog away from any male dog that is not neutered.
Yes, it’s a little tricky to predict ovulation. Technically the first days of estrus are safer in terms of unwanted pregnancy. Insemination by a male dog will not occur during the early days because it cannot happen before the ovulation. Ovulation is triggered by hormones several days after the beginning of the heat. While on average, dogs ovulate in the ninth day of the heat, it can occur anywhere from the 3rd and 17th day. That’s why it’s tricky because of the possible three day window. It’s even worse if you don’t know when the heat started.
It’s easy to miss the beginning of the heat. The first sign of the heat is a bloody discharge from the dog’s vulva, often incorrectly labelled as bleeding. But what if the bloody vaginal discharge is not red, but pink or yellow? Another confusing thing is your female puppy may clean herself so you don’t see any vaginal bleeding. Noticing the start of the heat is hard. Therefore you can’t quite know form when to start counting the days. And even if your vet takes blood tests to monitor ovulation, there is one more thing why breeding can still result in a pregnant dog. And that is…
Male dog sperm can survive up to 7 days inside the uterus. This works as evolutionary insurance since breeding in nature is not that predictable. Breeding as we know happens when two dogs meet, not when ovulation occurs. That’s why a male dog’s sperm is remarkably viable and can survive in the uterus of a female pup for several days. This means, forget about potential three day window that might be safe at the beginning of the heat. If your female dog has reached sexual maturity, any breeding can result in her becoming pregnant.

How do I know if my dog is in heat?

The symptoms your female puppy an exhibit may differ than another dog. Knowing when your dog’s heat cycle starts and ends as we’ve discussed is a little tricky. This can be frustrating if you are trying to breed her. We had one experience where we were breeding our female dog as she was a show winner and exceptional at obedience trials. She was also as sweet and calm as can be. All the qualities we wanted in a new puppy. So we bred her. Figuring out when to breed was the hard part. For more details plesae refer to our article on Symptoms of a female dog in heat.

So, can a dog get become pregnant while bleeding? Yes. Please remember, a female dog estrous cycle is not menstruation. The start of your dog’s cycle is the start of your pup’s fertile days. Where in humans, it’s the end of them. And, even if we consider the first days of the heat cycle as a warm-up phase, you cannot relax. Your female puppy can still get pregnant if there is an unneutered male dog around.