HealthBreeding & PregnancyCan a Big Dog Mate With a Small Dog?

Can a Big Dog Mate With a Small Dog?

Even though a big dog can mate with a small dog, it doesn’t mean you should let it happen. The risk of pregnancy or birth problems increases when two dogs of significantly different sizes mate. Make sure the mother is adequately cared for during pregnancy and delivery.

It is always interesting seeing puppies who have parents that are two very different sizes, but it also makes you wonder if this is okay for the dogs involved.

You may wonder how this can happen, if it’s only doable with certain breeds, and whether or not it is safe for the dogs involved.

In the following section, we will go over what classifies dog size, discuss whether big dogs can mate with small dogs, and whether or not there are consequences of these actions.

What Classifies a Small Dog and a Big Dog?

It’s important to know the classification of sizes because what you might believe to be a small dog could actually be a medium dog, vice versa.

First, let’s talk about size. You may wonder what classifies a small dog versus a big dog. This can be tricky, since there are categories within categories.

With small dogs, you have two different sizes: x-small and small. Extra small dogs typically fall in the “under 10 pounds” category, while small dogs can be 11 to 25 pounds.

Big dogs have three categories: large, X-large, and XXLarge. Large dogs are 50-70 pounds. Moving up, we have x-large dogs, which weigh in at 75-90 pounds. In the last category are our XXLarge dogs, which weigh in at 90 pounds or more.

Can Big Dogs and Small Dogs Mate?

The simple answer is yes, even if it seems impossible. If the female is in heat and is a big dog, she will lower herself to the ground for the mating to occur. In contrast, a big male dog can more easily mount a small female dog.

Should You Allow a Big Dog to Mate With a Small Dog?

Dogs have the instinctual desire to mate. If a male dog is around a female dog in heat, there will be the desire to mate, regardless of size. This means you, as the dog owner, have to decide whether or not you want that to happen.

When pairing a big dog with a small dog, there are several important considerations. This section will go over three of the most important considerations. We will also note what situation the consideration is important for (i.e., big male dog and small female dog, or small male dog and big female dog).


Small Male With Big Female

First, it is essential to consider how the physical act of mounting can affect the two dogs involved. A small male dog mounting a large female dog can be as harmful as a big male dog mounting a small female dog.

Harm can come to the small male dog in its attempt to mount the female, as they may try to climb on something to get high enough. Sometimes objects are not stable or slippery, which means the small male dog can get hurt if they fall.

When mating occurs, there is a point where the male dog will “lock” onto the female, thus keeping them attached anywhere from 15 to 40 minutes. The male dog typically lifts their leg over the female to entirely turn its back on them following the initial “lock.” It can be pretty tricky for the small male to lift their leg and turn around.

This attempt can cause harm to both the male and female involved as their genitalia are locked, and any tugging or pulling can hurt them and even create a tear in the female. The larger female can also move around while locked, potentially dragging the small male dog everywhere with her. This, again, can cause harm to both the male and female dog.

Big Male With Small Female

Similarly, harm can come during the mounting phase with a big male and a small female dog. This situation can be even more harmful in several ways. First, a big male dog mounting a small dog can squish or crush the small female dog. Secondly, although it is not usual that a big male dog will place all of its weight on the small female dog following mounting, the big male dog can decide to lie down, physically hurting the female.

Further harm can be done to the small female dog during the penetration process if the male is too large to penetrate. The attempts alone can cause damage.

If penetration occurs, the female dog is still not out of the water. Like with the large female dragging the small male around during the “lock,” the big male can also move around while still attached. Because of this, keep a close eye on both dogs and prevent as much movement as possible.


An important consideration is the age of the dogs, specifically the age of the female dog, as she will be the one carrying and delivering the babies later on. It can be dangerous for both a young dog and an older dog in either situation as their bodies may not be physically able to handle the difficulties of pregnancy.

Big Male With Small Female

This can be especially dangerous when mating a big male with a small female. Since the puppies will be larger, the pregnancy and delivery process will be more difficult.

There is not as much of a concern with a small male with a big female.

Pregnancy and Delivery

If successful mating/mounting has occurred, a final (but just as equally vital) consideration is pregnancy and delivery. This is mainly for the mating between a big male dog and a small female dog.

Believe it or not, the more puppies a female is carrying, the better the delivery will be. This may seem counterintuitive, but more puppies will equal smaller puppies at birth. The puppies must share space inside the uterus. The uterus will only grow to a certain size regardless of how many puppies the female is pregnant with. So when a female is pregnant with more puppies, she will deliver small puppies.

In contrast, fewer puppies can be not only critical to her health throughout pregnancy, but during delivery, a C-section is going to be the most likely outcome.

The problem when mating a big male with a small female is that if she gets pregnant with fewer puppies, she will give birth to larger puppies than she would have if she mated with another small dog.

It’s important to have an ultrasound performed to know how many puppies a female is carrying. Depending on the number, a scheduled C-section may be recommended.

Proceed With Caution

Although a big dog can mate with a small dog, that doesn’t always mean it’s the smart thing to do. If you decide to mate a big and small dog, do so with caution. Be aware of all the concerns and make sure you’re able to monitor the mating process in case anything goes wrong. Keep a close eye on the female dog during the pregnancy and be sure to get an ultrasound to find out how many pups she’s carrying.

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