Why Dogs Get ‘Stuck’ Together During Sex, and What Do to About It

Written by Sharon Parry
Updated: October 24, 2023
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Quick Answer:

  • It happens because a section of the erectile tissue at the base of the male dog’s penis called the bulbus glandis gets very engorged with blood.
  • The bulbus glandis swells very rapidly and soon measures more than two times the diameter of the rest of the shaft of the penis, thus getting stuck in the female’s vagina.

If you have ever tried breeding dogs or even witnessed an accidental mating, you may have come across a seemingly bizarre occurrence. The dogs appear to get stuck together and cannot separate after having sex. If you are not aware that this can happen, it can be very alarming. However, this is something that is very common in the dog world. So, why do dogs get stuck when they mate? We examine this unique canine phenomenon and give you top tips from vets and experienced dog breeders on what you should do about it.

Why Do Dogs Get Stuck When They Mate?

Getting stuck together during mating is such a normal thing for dogs that it even has its own medical name. It is called a “copulatory tie” and is also seen in wild canines such as wolves and foxes. It happens because a section of the erectile tissue at the base of the male dog’s penis called the bulbus glandis gets very engorged with blood. This happens after the penis is inserted into the female and is triggered by the male dog thrusting. The bulbus glandis swells very rapidly and soon measures more than two times the diameter of the rest of the shaft of the penis. As a result, it gets stuck inside the female’s vagina (birth canal).

At the same time, the circular muscles at the entrance to the female dog’s vagina (the constrictor vestibuli muscles) contract and prevents the penis from moving back out. This results in a very secure lock and the dogs are tied together.

There is nothing that the dogs can do about it. It is completely out of their control.

What Role Does the Copulatory Tie Play in Breeding?

To understand this, we need to consider normal mating behavior in dogs. This usually starts with a male dog sniffing a female dog to check that she is on heat and therefore receptive to mating. However, she may also display her willingness to mate by presenting her butt in his direction and holding her tail to the side.

Once the male dog mounts her and begins to thrust he has a first ejaculation during which a pre-sperm ejaculate is released from his penis. It is after this that the bulbus glandis swells and the female dog’s constrictor vestibuli muscles contract. This forms the copulatory tie and the dogs are locked together. At this point, the male dog stops thrusting and ejaculates his sperm into the female.

After dismounting but whilst still in the copulatory tie, the male dog finally ejaculates the post-sperm fraction of the ejaculate. This can take anything from 5 to 30 minutes.

What Does a Copulatory Tie Look Like?

Once the male dog has ejaculated, he dismounts the female and turns around at a 180-degree angle so that the dogs are now facing in opposite directions. However, his penis is still ‘locked’ inside the female. They look like two dogs that have their butts glued together. It sounds quite comical but is very alarming if you have not seen it before or have no idea what it is. Dogs can stay like this for over half an hour.

Why Is the Copulatory Tie Needed in Dogs?

Every type of animal has adapted to give themselves the best chance of producing young. For example, cats become fertile (it’s called queening) every 21 days or so. This gives them loads of chances every year to become pregnant. However, female dogs are only fertile twice a year. It is called being “in heat” or “in season.” Dogs need to make sure that they make the most of these rare opportunities to mate. So, they have evolved to have a copulatory tie.

When the dogs are locked together, during and after ejaculation, it traps the sperm inside the female. This gives it the best chance of reaching and fertilizing the egg to produce a litter of pups.

How Long Does the Copulatory Tie Last?

Not every mating has a copulatory tie or it may be so brief that you don’t notice it has happened. However, for most dogs, it lasts between 5 and 15 minutes. In some cases, it has gone on for 45 minutes.

For dogs that are mating for the first time, this can be distressing. For others, it is what they expect to happen.

Dogs that are mating for the first time may be distressed by the duration of the copulatory tie.


The Copulatory Tie and Pregnancy

There are a lot of myths surrounding the copulatory tie so let’s look at the science to get the truth. As long as a male dog ejaculates inside the female, there is a chance that she can get pregnant. The copulatory tie is not necessary but it greatly increases the chances of pregnancy. Therefore, breeders look out for it as a sign of successful mating. They also think that the longer the copulatory tie lasts, the higher the chance of a successful pregnancy. This makes scientific sense because the sperm has longer to reach the egg.

However, the fact that there has been a copulatory tie does not guarantee a pregnancy. There are loads of other reasons affecting both the male and female dog that can prevent fertilization from taking place.

So, the bottom line is that a copulatory tie is a good sign but there are no guarantees when it comes to animal breeding.

Pregnant Jack Russell terrier

This Jack

Russell terrier

has been successfully mated as evidenced by her pregnancy.

©Pavel Shlykov/Shutterstock.com

What to Do About a Copulatory Tie

This is the one dog behavior that you should do nothing about! A lack of breeding experience can make some dogs distressed during the process but unfortunately, there is nothing that you can do to help. You simply have to let nature take its course.

Never try to forcibly separate the dogs because this can cause injury and a lot of distress to both of them. It also decreases the chances of a successful pregnancy. If you don’t want your dog to get pregnant, you must take steps to keep her away from males when she is on heat. Once a copulatory tie is underway it is too late!

Watching a copulatory tie can be very uncomfortable and distressing for inexperienced dog owners but it is essential that you keep calm. If you panic, it will make the dogs even more anxious and make the situation worse.

What Other Animals Get “Stuck” When Mating?

pair of mating Lovebugs - Plecia nearctica - a species of march fly found in parts of Central America and the southeastern United States,  isolated on white

Love bugs don’t bite, sting, or cause any other harm, but they can be a nuisance when they swarm at certain times of the year.

©Chase D’animulls/iStock via Getty Images

Have you ever heard of the “love bug?” This insect, also called the honeymoon bug or double-headed bug, got its name based on the fact that mating pairs stay connected for days on end. Even after mating is over, they can remain joined together, even in mid-air flight. These bugs are native to the southeastern United States and Central America, as well as Australia. They are beneficial insects in the respect that they eat decaying vegetation. On the flip side, during mating season, they often hover over heavily trafficked highways, meeting a sad end on the front bumpers of moving cars.

Some folks like to celebrate the love they ascribe to these insects with celebrations in their honor. One such festivity that occurs annually around the time that love bugs are the most prominent is the Love Affair Arts Festival held in Tifton, Georgia. It takes place the last weekend of April or the first weekend of May. While the festival is focused on fine art, live music, and acting troupes, it received its name from the dense population of love bugs that come out to party that time of year.

The photo featured at the top of this post is © Jesse Kunerth/Shutterstock.com

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About the Author

Dr Sharon Parry is a writer at A-Z animals where her primary focus is on dogs, animal behavior, and research. Sharon holds a PhD from Leeds University, UK which she earned in 1998 and has been working as a science writer for the last 15 years. A resident of Wales, UK, Sharon loves taking care of her spaniel named Dexter and hiking around coastlines and mountains.

FAQs (Frequently Asked Questions) 

Does it hurt dogs to get stuck together when mating?

During a first breeding, it is possible that the dogs can experience some discomfort and/or anxiety. It actually makes matters worse if you try to break the copulatory tie and you will only cause more distress. As they become more experienced, it will not be a problem.

Why do female dogs cry when mating?

This is usually because the female dog wants to get the male dog’s attention. It happens when she is on heat and therefore receptive to mating. You may also notice that she places her head on her back and paws at him. Some females will even mount a male dog to let him know that she is ready to mate.

Do neutered dogs have a copulatory tie?

Most neutered male dogs will not have a copulatory tie because the bulbis glandis will not swell. However, if your dog has only recently been neutered, it can happen because he will still have a lot of testosterone in his body.

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