Can Big Dogs Mate With Small Dogs?

Can Big Dogs Mate With Small Dogs? Photo of a big dog and a small dog looking to each other.

It’s one of those questions that dog lovers often have in their mind, right? Curious as if can big dogs mate with small dogs and how it actually happens? Take a look and get the real deal!

Technically, yes, big dogs can mate with small dogs. The actual mating or fertilization process doesn’t discriminate between sizes. As long as the fertilization itself occurs, a dog can fall pregnant.

However, mating naturally (as opposed to artificial insemination) is difficult if two dogs are of different sizes. Pregnancy can also be dangerous if the mother-to-be is the smaller of the two dogs.

Can a small male dog get a large female dog pregnant?

It seems sort of impossible, after all, right? The size issue would be that a male dog wouldn’t even be able to mount a female to impregnate her. It is actually possible for natural mating to occur with help (more on that later).

When crossbreeding a small male with a large female, however, most will look at artificial insemination to ensure the success of the breeding itself.

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How much bigger can the male dog be compared to the female?

There is a comfortable area where the size difference is safe and usable as far as mating is concerned. The two main areas of concern when it comes to the female’s body instead of the male’s body include:

  • The size of your female dog’s reproductive organs
  • The capacity of the female dog’s womb

It sounds obvious, but many don’t think about this! Her reproductive organ (more specifically, her vagina) will only be able to withstand so much stress and force. So, a male dog’s larger size will do damage if she isn’t big enough to accommodate her.

A male dog who is considered too big in this sense could cause tearing in her and create discomfort, injury, permanent damage, and even cause internal bleeding. It’s important to consult a vet or another expert to help you determine whether natural insemination is the best way to go.

In most cases, professionals will recommend artificial insemination so that Mom isn’t stressed out about her organs. This promotes comfort and accuracy in the fertilization process.

The other consideration is the size of her womb. If a large male dog is mating with her and she only has so much space in her womb, it will stunt the growth of the puppies to accommodate the space needed for all of them. It can also easily lead to abortions, miscarriages, and stillborn puppies if there aren’t enough resources available for mom-to-be to go around.

Even when there is only one fetus growing, the puppy will be a mixed breed of Mom and Dad, and it will be automatically larger than Mom’s natural ability to deliver. A c-section is often the best approach for those situations so that the Mom isn’t stressed out with the delivery.

No matter how you look at it, a male dog can only be a certain amount larger than a female dog to have successful fertilization, pregnancy, and delivery of a litter of puppies. As far as maximum size difference, the actual numbers themselves will vary depending on the two breeds, their health, and other individual factors. Professional breeders and vets will be able to tell you more.

What happens when a big dog breeds with a small dog?

If you know anything about dog breeding, you will know that there are a lot of metrics that have to be considered. However, this is a business, and it’s how mixed breeds (aka designer breeds) are created. 

The mixed-breed puppy will be a blend of both parents, with a mix of coats, traits, and sizes. Puppies will take on more of one parent’s genes than the other in most cases, depending on DNA and the breeding process. Every puppy in every litter is going to be unique. That’s why mixed breeds are an incredible option and opportunity.

When a large and small dog mate, there are three stages to the process, all of which can be at-risk depending on the size difference:

  • Incomplete fertilization
  • A high-risk pregnancy
  • Puppy health

If a male dog is much smaller or larger than the female dog, it may be difficult for him to mate successfully and fertilize her eggs. This will lead to incomplete fertilization, meaning that your dog is more likely to miscarry or simply not fall pregnant.

Mom-to-be will also be more likely to have a high-risk pregnancy if she is the smaller of the two. This is often why the female dog is the larger of the two! However, if you mix two types of dogs in one combination breed, there can be a high-risk pregnancy for the Mom and puppies. The risk itself will vary depending on the size difference. This risk starts from the beginning of her pregnancy to delivery. 

Lastly, puppies need a certain amount of resources and space to grow properly. If Mom-to-be is too small, the puppies will often be undersupported, malnourished, and even stunted. When breeding with differently-sized breeds, you’ll need regular and experienced vet care to watch everyone’s health!

Health concerns on breeding big dogs with small dogs

The health of Dad, Mom, and puppies should be the priority of any pet parent and/or breeder. There are several health concerns around breeding big and little dogs, which is why they cost so much money!

Most of the health concerns will be on Mom and the puppies. Mom needs to have a successful mating experience where she is calm and contained and can have the best chance at fertilization. She also needs a special diet and lots of rest and support while pregnant. This will help her stay strong and her puppies, too.

The puppies will also need a lot of support and care. This includes proper check-ups and a controlled delivery that will give everyone support as needed. An experienced vet should be on-call so that they can spot signs of distress and intervene as needed. 

Many will also recommend having the option of a c-section if things go south with Mom or the puppies during delivery. This is more likely to happen with smaller mothers, of course, than with larger ones. 

Is my dog too small to have puppies?

Yes, this is definitely a possibility. Sometimes your mom dog is too small to have mixed breed puppies with larger male dogs. This is why breeding is such a specific and expensive process!

Breeding is always a risk when going with smaller mother dogs. You’ll need to have the guidance of a professional breeder and a professional vet. Better yet, always rely on an experienced breeder rather than trying to do it yourself!

How to breed different size dogs

If you are looking at breeding different size dogs nonetheless, you know a bit more about what to expect. Below are some reminders to help you make it a success and to keep everyone safe from start to finish:

  • Have both dogs checked out by vets for their health
  • Have a vet you can trust on hand through the process of breeding
  • Understand the mating process before you begin
  • Learn about the process from a medical point of view
  • Be ready to intervene at any point

From mating to the pregnancy to the delivery of the puppies and beyond, you’ll need to stay in control of the situation by arming yourself with knowledge and know-how about breeding and puppies.

If this is your first time breeding dogs, be them the same size or two different sizes, and have an experienced breeder and a vet at your disposal for questions, concerns, and more.

There are real consequences to not having proper support and experience in breeding. It could result in failed pregnancies, injury to parent dogs, and even deaths of either parent or puppies. Take this responsibility seriously for everyone’s benefit.

How do small dogs mate?

So, how do small dogs mate when it comes to a successful pregnancy? Most of the same things will apply as above; however, most will find that your dog will require some extra support in the mating process itself.

A male dog will need to be able to safely and easily mount the female and ensure that he can successfully mate with her that way. Human interaction is often needed to provide the platform for the male dog and to hold the female steady once he starts. You may need to help him rotate while the fertilization lock takes place, as this can take up to an hour at a time.

In cases where the breeding process is too stressful on the male dog (and female), you’ll want to seriously consider artificial insemination! It will guarantee a much better result with no stress or injury on either dog! Or you, for that matter.


Big dogs can mate with small dogs just as easily as two that are the same size, but there will be more of a risk to it.

Mating is possible between large and small dogs because the fertilization is not size-dependent in and of itself. Mating between two drastic size differences can be difficult, risky, and require human support and interference.

You’ll need to understand what is risky, where the risk is, and how to spot it so that you are not putting anyone’s health at risk. Understanding the process and experience with it from a professional point of view will be considerable support to successful pregnancies and litters of puppies!

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Andre Neves

Hi, I'm Andre and I'm the owner of Sula the Border Collie. I love writing about this amazing dog breed here. I joined the Council to be able to reach and educate more people on the joy of having a pet dog.