Whether your doe’s pregnancy was intended or the result of an “oops!”, there are important pieces of information you need to know to ensure the health of her pregnancy and future pups.
You may be wondering how to best care for the expecting doe and her pups. What nutritional needs does a breeding rat have? What does a rat birth look like? What are problematic signs to look out for?
Here is our guide for caring for a pregnant rat, starting from the breeding process until her pups are fully weaned.
Preparing for the Pregnancy
Choose The Mating Pair
If you intend to breed your rats, the very first step is being sure that you will be able to find homes for the pups (or keep them yourself, of course). In many areas, shelters are already overpopulated with rats, and it might not be responsible to breed your females.
The next step is choosing the mating pair.
Both rats, but especially the female, should not be too young when first mated. Male rats can reach sexual maturity as early as 6 weeks of age1, so it’s important to keep them separate from females to avoid unwanted pregnancies.
Females rats will be biologically ready to breed at 8 to 10 weeks1, but this is far too young for them to have pups. It’s best to wait until the rat is fully grown and more mature.
Anecdotally, we see more complications in first pregnancies that occur after the doe is 10-12 months of age2, so the ideal time to first breed your doe would probably be between 6 and 8 months of age.
When choosing your breeding pair, ensure that both the buck and the doe are healthy individuals and ideally come from healthy parent animals.
Some breeders choose to breed two females at the same time, in case there are problems with lactation or if one female turns out to be unfit to care for her pups – that way, there is another dam ready to help out.
While a pregnancy can take a toll on your female rat’s body, it also has some health benefits for her. Pregnancy and lactation alter the mammary tissue so that it becomes less likely to develop tumors – and this is a lifelong effect3.
Separate The Doe You Intend To Breed
Before you initiate the breeding process, you should separate the doe, so she has her own space away from other rats. This separate cage will home your doe and buck during the mating process.
In case you have more than one female, this will ensure that only the intended doe becomes pregnant. You don’t want to end up with multiple pregnancies if you’re only prepared for one!
Once it becomes obvious that your female is pregnant, you should remove the buck. The cage now becomes a sanctuary for your breeding female and later for her pups.
If you have a multi-level cage, you could block off one level for the breeding doe. If that’s not possible, an extra cage will be necessary.
Keep in mind that your pregnant rat will need to use this cage for the first six weeks following the birth, too. This will help keep stress levels low for your soon-to-be mama and keep the pups safe after birth.
The cage for the breeding doe should have only one level to minimize the risk of pups falling. Avoid cages with bars, as they can cause injuries in newborn pups.
Provide Soft Bedding And Nesting Materials
Now that babies are on the way, you will want to make sure you are using the best bedding for your rat.
Pregnant rats have a strong nesting instinct, so shredded cardboard or paper, tissues or fabric make an ideal bedding and nesting material1. Offering a combination of all these is ideal, so your rat can choose her preferred nesting material.
Due to its high absorbency rate, corn cob bedding should be avoided because of the risk of ringtail developing in pups.
Building a nest enables your dam to better regulate her own body temperature as well as that of her pups.
A study in mice has shown that offering paper nesting material resulted in more healthy pups4. Another study indicated that offering an igloo resulted in 76% more pups reaching weaning age5.
Give your rat plenty of choice in the matter by offering shelters of various materials, shapes, and sizes, so she can choose the best location to build her nest.
Once her nest is built, you should not disturb it. The breeding cage does not need be cleaned as thoroughly as you would your regular cage. You should, of course, remove droppings and clean the litter boxes, but leave the nest alone.
Nutrition Is Key For Your Pregnant Rat
Following nutrition guidelines is important when caring for a pregnant rat. Along with her regular food, you will need to increase the mama-to-be’s protein intake. The nutrients found in fruits and vegetables are more beneficial than ever, too!
Protein is an essential nutrient for a pregnant rat because it aids with the healthy development of her pups during gestation. Good sources of protein are cooked chicken and fish, scrambled or hard-boiled eggs, quark or non-salted cream cheese, and mealworms.
Another option is to switch your female to a high-protein commercial rat food made especially for breeding rats.
Fruits & Vegetables
Most fruits are a good source of vitamins and antioxidants, both of which are beneficial for the health of your rat’s pregnancy. Since they are also high in sugar, you should aim to offer no more than one tablespoon of fruit per day. Popular choices among most rats are bananas, berries, and grapes.
Vegetables for Pregnant Rats
Most vegetables can be offered cooked or raw – potatoes and sweet potatoes should be fully cooked, and cruciferous vegetables will be more easily digestible in cooked form. Vegetables should be a staple in your pregnant rat’s diet along with fruit such as blueberries and strawberries. Nutritious vegetable choices include bok choy, carrots, broccoli, and peas.
Commercial Rat Food
The commercial rat food given to your rat prior to pregnancy should still be offered every day. If protein is a concern, you can slowly introduce a higher protein brand during this time.
The benefit of most commercial rat foods is that they are formulated to meet your rat’s nutritional needs, so your pregnant rat will still benefit from eating it!
It’s crucial to keep feeding your dam this special diet after the birth, too. While she is lactating, your female will still require more calories and protein.
Studies have shown that offering foraging treats such as dried mealworms (high in protein) and sunflower seeds (contain healthy fats) decreases the chance of cannibalism in dams5.
The Mating Process
Now that we’ve looked at the importance of separating the intended mother, using soft bedding materials, and changes in nutritional requirements, we can focus on the processes involved within your rat’s pregnancy.
We’ll start with the mating process:
If your doe doesn’t try to fight her mate, an easy way to initiate the mating process is keeping the breeding pair together for 10 days. During this time, your female rat should go through two separate heat cycles, so the chances of pregnancy are quite high.
Otherwise, you will have to keep the pair separate unless you are certain the doe is in heat. Signs to look for are an arching of the back when touched, vibrating of ears, urine marking or frequent urination, and running in short but quick bursts.
The doe typically initiates the mating process by sniffing the male’s genitals, darting around the cage, or arching her back. From here, the male will take over. This process can last anywhere from 2-24 hours with up to 100 single sessions.
Pregnant Rat Care
Once you are certain that mating has occurred, you need to separate your newly pregnant rat and her partner. This is important for the safety of the future pups and avoiding an unwanted pregnancy from occurring right after birth.
In most cases, pregnancy will be detectable after about 2 weeks. You will notice that your doe’s belly gets rounder and her mammary tissue and nipples become more developed or swollen.
Pregnant Rat Belly
The gestation period lasts between 21 and 23 days.
During this time, you might notice behavioral changes in your pregnant rat. She might become more aggressive and territorial or more relaxed if she was flighty before the pregnancy. Her appetite will increase as her body adjusts to the demands of pregnancy and she might stash food more often than before.
Some time during the pregnancy, your rat will also build her nest from any loose material you will offer her. The nest is where she will give birth and where the pups will spend the first few days of their lives, before they will start venturing further.
Shortly before birth, you may notice hair loss around your rat’s nipples. This makes nursing an easier process for her newborn pups.
Let your doe (now almost a dam) take the lead on your interactions.
If she seeks your company, she will benefit greatly from cuddling and playing with you. However, she might retreat and avoid any interactions. If this is the case, let her be. Handling her against her will can cause unnecessary stress and – at worst – complications with her pregnancy.
The Birthing Process
In most cases, does are naturally equipped to handle the birth process on their own. The entire process should last between 1-2 hours. If your doe hasn’t given birth two hours after you first notice contractions, it’s recommended that you seek the advice of a veterinarian.
There are four stages involved in the birthing process:
Hormonal: The building of the nest is typically the first sign you’ll notice with an expectant mother. Unfortunately, it isn’t a foolproof indicator that the birth is going to happen soon because it can occur weeks or hours before the arrival of pups.
Spotting Blood: If you find a light spotting of blood in the cage, there is a good chance your doe will give birth within the next 24 hours. Excessive amounts of blood or dark brown spotting are not normal, and you’ll need to seek veterinary care immediately.
Labor: A clear sign your doe is in labor is the hunching of the back or stretching out during contractions. Many rats will show “bruxing” (grinding their front teeth together) during labor. During this time, she should be left alone but you should monitor from a distance for signs of trouble like gasping for air, extreme agitation, or lethargy.
Birth: When birth begins, you can expect each pup to arrive one after the other. They can arrive in either position: head first or rump first with your female aiding in the delivery by gently using her front paws and teeth. By licking each pup, she clears a path to the airway and helps oxygenate their blood. It’s normal (and beneficial!) for the doe to eat the placenta from each pup.
It’s important to keep your doe comfortable and avoid interfering unless necessary. For these reasons, you’ll want to have the cage setup for easy viewing and emergency access prior to the start of your doe’s labor. Make sure that the environment is quiet and disturb her as little as necessary.
It’s most common for the birth to take place at night so there is a good chance you’ll miss the process entirely – only to wake up to the sound of unfamiliar squeaks the following morning!
Following The Birth
The usual litter size is 8 to 18 pups, so you can expect quite a few new members to the family1!
The first few days following the birth should be reserved for the dam and her new pups. Give them space and a quiet environment. The litter should not be disturbed for at least 7 days after birth, especially if it’s the female’s first litter1.
The only reason to touch a pup before that is if it’s in distress or in need of veterinary assistance, for example if the mother has removed it from the nest and is not taking it back in.
The less you disturb your dam and her pups, the less likely she is to reject the pups or resort to stress-related cannibalism.
Your doe will be the primary source of nutrients for her pups until the third week of life, when they will start eating solid foods. Until the pups are mobile, she’ll stay with her babies in the nest to nurse and provide warmth.
During their fifth week of life, you will need to definitively determine your pup’s sex and separate the males after week 5.
At six weeks, the pups are fully weaned and ready for their new homes, but they will also benefit from staying with you a while longer. The female pups can stay with their mother for as long as you like.
Here’s everything you need to know about raising baby rats week by week.
Your dam should be given a rest period of at least 2 months before her next pregnancy, if you intend on breeding her again1. This will allow her to regain her strength and establish reserves to meet the demands of pregnancy and lactation.
If the rat was very stressed during pregnancy and postpartum or if she didn’t take optimal care of the litter, she is probably not a good choice to breed again.
Keep in mind that females can go into heat the day after giving birth6. This is called “postpartum oestrus”. This is yet another reason why it’s crucial to separate the buck from the female before she gives birth.
The next time your female goes into heat will be after weaning, usually around 29 days after the birth of her pups7.
Her male offspring will reach sexual maturity shortly afterwards and should be separated from their mother at 5 weeks (6 at the very latest) to keep them from trying to mate with her.
Researching and educating yourself on the needs of your pregnant rat is crucial for ensuring a healthy pregnancy, birth, and overall quality of life for the future pups.
Breeding fancy rats requires a lot of work and dedication, so it is not a task that should be taken on lightly. We hope to have given you the tools to raise healthy and happy rat litters.
1. MSD Vet Manual. Breeding and Reproduction of Rats. 2020. https://www.msdvetmanual.com/all-other-pets/rats/breeding-and-reproduction-of-rats.
2. Rat Breeding Guide. Labor and Birth 2006. https://ratguide.com/breeding/birth/labor_and_birth.php.
3. Russo J, Russo IH. Experimentally induced mammary tumors in rats. Breast Cancer Res Treat 1996;39:7-20. https://pubmed.ncbi.nlm.nih.gov/8738602/.
4. Gaskill BN, Pritchett-Corning KR, Gordon CJ, et al. Energy Reallocation to Breeding Performance through Improved Nest Building in Laboratory Mice. PLoS ONE 2013;8. https://docs.lib.purdue.edu/cpbpubs/12/.
5. Lecker J, Froberg-Fejko K. Using environmental enrichment and nutritional supplementation to improve breeding success in rodents. Lab Animal 2016;45:406-407. https://doi.org/10.1038/laban.1114.
6. Gilbert AN. Postpartum and lactational estrus: a comparative analysis in rodentia. J Comp Psychol 1984;98:232-245. https://pubmed.ncbi.nlm.nih.gov/6478785/.
7. Mennella JA, Moltz H. Infanticide in rats: male strategy and female counter-strategy. Physiol Behav 1988;42:19-28. https://pubmed.ncbi.nlm.nih.gov/3387474/.
Nina has a degree from the Veterinary School in Zurich, with a special focus on microbiological research. Nina has a passion for sports, nutrition and the outdoors and she loves all pets, but rats have a special place in her heart. When she’s not working or reading and writing about all things related to pet health, she loves to travel and surf.
As a small animal veterinarian, Nina is your go-to expert on pet health and nutrition.