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Home > Rodents > How To Tell If a Pet Rat Is Pregnant: 8 Vet Approved Signs To Look For

How To Tell If a Pet Rat Is Pregnant: 8 Vet Approved Signs To Look For

white pregnant rat

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Dr. Luqman Javed

Veterinarian, DVM

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

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Rats make great pets. They are typically bigger than mice, hamsters, and other small, caged animals. They can be quite affectionate and really enjoy being handled. They are also intelligent, and some can be trained to perform basic tasks. As such, it is understandable that some owners try breeding their rats to increase the size of their rat family. On the other hand, rats are known to breed quickly, and their pregnancies can be difficult to spot.

In either case, whether you want your rat to get pregnant or not, there are certain signs that you can look for to help determine whether you should be expecting a litter of baby rats shortly.


Rat Pregnancy

A female rat’s estrus cycle lasts 4-5 days. During this cycle, she is receptive towards male rats for a period of about 1-2 days (during estrus). If you are trying to mate your rats, this is the time that the male should be introduced to the female. Once pregnant, a rat’s gestation period is around 21-23 days, and the whole litter of between 8 and 18 pups is usually delivered within 24 hours.

The 8 Signs To Look For

If your rat is pregnant, you will, at the very least, need to find the young rats new homes within a couple of months of them being born. Alternatively, if you plan to keep them, you will need more cages and more supplies. In any case, it is beneficial to be able to spot when a rat is pregnant to allow you to plan accordingly. Below are some of the most common signs to look for.

1. Look for a Plug

After mating, a small amount of semen is left aroundthe junction of the female’s cervix and vagina. This can sometimes be seen as a plug on the female’s vulva. This hardens and acts as a plug to prevent further mating. It will stay in place for between 24 and 48 hours and is usually visible during this time. After 48 hours, you might be able to see the plug on the ground of the cage. A plug does not guarantee that your rat is pregnant but is a sure sign that mating was successful.

2. Increase in Appetite

A rat will usually gain weight during pregnancy. This will happen quickly at first before any gains level off during the later stages of pregnancy. During this time, you may notice your rat’s appetite increase. As well as eating more, your rat may also gather food and store it ready for the impending birth.

mice eating
Image By: Piqsels

3. Nest Building

Rats are nest builders, and a pregnant female rat is likely to start building a nest during the relatively early stages of pregnancy. She will look for a secluded spot, usually in a corner or dark area of the enclosure, and start moving nesting material and other material to create somewhere to give birth and rear the young.

4. Behavioral Changes

Your pregnant rat may exhibit some behavioral changes. Such changes may mean that an otherwise placid rat will be less tolerant of company in her cage. She may also become aggressive with you, especially if you try to touch her pregnant belly.

pet mice on human hand
Image By: Sergey Bezgodov, Shutterstock

5. Lethargy

Pregnancy puts a physical strain on a rat’s body and this strain can take its toll. If you notice your rat sleeping longer and more often, this could be a sign of pregnancy. It may also be a sign of illness or an indication that your rat is aging and slowing down.

6. Aggression

When handled from a young age and regularly throughout their lives, rats not only tolerate being handled by their humans but seem to really enjoy it. However, when pregnant, they can become less tolerant of handling. One of the few ways they object to being handled is to bite. If your female rat has started biting when you handle her, it may not be a change in personality but a sign that she is pregnant and doesn’t appreciate being picked up.

close up of a rat
Image By: Denitsa Kireva, Pexels

7. Swollen Abdomen

A swollen abdomen is a sign that your female rat has a litter of young growing. This is most prominent at the second week of pregnancy. If the litter is a small one, the swelling may not be as prominent, but if she is expecting a lot of pups, the swelling can be very easy to spot.

8. Prominent Nipples

Your rat’s nipples may darken when she is pregnant. If yours has fair fur on the belly, then this will make them more visible, heightened further by the fact that the nipples will likely swell during this time.

curious white pet rat looking out of a cage
Image By: Kirill Kurashov, Shutterstock



Rats can have dozens of young every year, and they can become pregnant even while still nursing a litter of pups. If you believe your female is pregnant, you should remove the male from the cage to prevent putting too much pressure on the mom’s body with a subsequent pregnancy. Ensure the mother is well fed, do not touch the babies for the first week, and be prepared to separate the young before they reach sexual maturity, so as to avoid the pups mating and having young of their own.

Featured Image Credit: Elena M.Tarasova, Shutterstock

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