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Can a Small Dog Get Pregnant by a Large Dog? Vet-Verified Risks

Written by: Kristin Hitchcock

Last Updated on June 11, 2024 by Dogster Team

Golden retriever dog sitting close to white short hair Chihuahua

Can a Small Dog Get Pregnant by a Large Dog? Vet-Verified Risks


Dr. Paola Cuevas Photo


Dr. Paola Cuevas

Veterinarian, MVZ

The information is current and up-to-date in accordance with the latest veterinarian research.

Learn more »

Yes, large dogs can get smaller dogs pregnant. Technically, any dog can reproduce with a larger dog. Fertilization does not care about the size of the dogs involved.

However, it is more complicated for different-sized dogs to mate. The size difference can make mating a bit difficult, so there is less chance that it will happen naturally. When a small female becomes pregnant by a large male, there are serious medical concerns. Because the male is larger, the fetuses likely will be as well. This larger size means this is a high-risk pregnancy, and the health of the female and pups is at risk.

Therefore, it is not recommended that small females mate with larger dogs. If breeders try to combine two breeds of different sizes, they usually artificially inseminate the larger female with the sperm of the smaller male. This process is much safer for females and puppies.

If a female accidentally becomes pregnant by a much bigger male, there are many critical medical decisions to make after considering the risks.

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Health Concerns When Breeding a Larger Male with a Smaller Female

Two large dogs sniffing a small dog
Image Credit: Jaromir Chalabala, Shutterstock

Whether it was purposeful or not, several problems can arise when a small female carries the puppies of a substantially larger male.

During the Mating Process

First, there are health problems associated with the act of mating. If the size difference is significant, the male could injure the female when attempting to breed with her. The breed of the female can also play a role. Some petite females have sensitive spines and are prone to intervertebral disk disease (IVDD). While this isn’t an issue in regard to mating with a dog of a similar size (usually), it can be a problem with bigger-size males. The male could injure the female’s spinal column, causing pain and paralysis.

In most cases, the female won’t have to hold up the whole weight of the male. It really depends on the specifics, but the difference in weight is a factor. When the male is larger than the female, the risk of injuries such as pelvic fractures and other forms of trauma is also higher. Some males are rougher during the mating process than others

It is also possible for the male’s penis to be much too large for the female. Mating attempts could result in the female’s vagina or uterus being injured, torn, prolapsed, or otherwise mutilated. The dogs must be kept very still if the male successfully penetrates and forms a lock.

The male may also decide to lie down after the lock, potentially squishing the female if she is too small. He will unlikely turn around and navigate away from the female if she is tiny.

Pregnancy and Birth

If the mating goes successfully without hurting the female, you still aren’t out of the woods. Pregnancy and birth can be hazardous for the female. As you’d likely guess, a female’s uterus and birth canal are made to accommodate puppies of her size. When you breed her with a giant dog, there is a significant chance that the fetus will be larger than her uterus and birth canal can accommodate.

There is a significant possibility that she will need a C-section to deliver the puppies. Most of the time, they’ll be too big for her to push out of her body. Without intervention, the females and puppies will die. Luckily, the puppies will not grow too big for the female’s uterus. Their size will be constricted somewhat by the female’s size. They can’t grow bigger than the female is; it isn’t possible.

In these cases, the more puppies the female is carrying the better. When there are more puppies, their growth is restricted since they have to share the space with other puppies. Sometimes, this growth restriction makes the puppies small enough for a standard delivery.

However, a single-pup pregnancy of a mismatched size male puts the female at higher risk of fetomaternal disparity; since this puppy will have the space to develop even more inside the womb. This is a serious consideration because we know that small and miniature dogs normally have smaller size litters1.

An  X-ray and ultrasound can help to determine whether the puppies are too large for normal birth. You’ll need to work closely with a vet to ensure the female survives the pregnancy and the birth.

pregnant jack russell in bed
Image By: Gladskikh Tatiana, Shutterstock

Can a Chihuahua Get Pregnant by a Large Dog?

Absolutely. Usually, the mating is clumsy and not consistently successful. The male can’t always line things up right, which can make mating difficult or even impossible. If you have a Chihuahua, mating opens up a whole can of potential health problems. Chihuahuas should only mate with dogs of a similar size, which limits their possibilities to other Chihuahuas and toy-sized dogs.

If they mate with larger dogs, they are prone to injuries during mating and afterward. Their puppies will usually need to be delivered via C-section. We highly recommend spaying or neutering your Chihuahua and any other female dog if you aren’t a breeder. It’s the only sure way to prevent potentially fatal health problems from cropping up after accidental mating.

Chihuahua with a cone
Image Credit: padu_foto, Shutterstock

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Final Thoughts

Small female dogs can become pregnant by larger dogs if they are left unsupervised while the female is ovulating. However, that is never a good idea! When paired with much larger dogs, the female can be injured during the mating process. The act of mating can cause injuries to the female’s genitals, pelvis, or spine. Sometimes, severe injury and even death can occur. After the dogs lock, the male can drag the female around and injure her.

The pregnancy is considered high-risk and is very likely to be hard on the female. The fetuses can grow too large to fit through the birthing canal. In these cases, a C-section is necessary.

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Featured Image Credit: Tamara Bellis, Unsplash

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