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This article is from the Rat Health Care booklet. Order one today! Check out the info at Rat Books

Raising Orphaned Rats

By Debbie “The Rat Lady” Ducommun

It’s very difficult to hand raise a baby rat less than 2 weeks old. The best option is to find a nursing rat to serve as a foster mother. As long as the babies are about the same age as her own, mother rats are almost always willing to adopt orphans. The best way to locate a foster mother is to contact local breeders, pet shops, or rat rescues.

If a foster mother isn’t available, the only alternative to save an orphan is to raise him yourself. When attempting to raise an infant rat, there are three elements to consider: warmth, hygiene, and diet.

Until their fur grows in, baby rats can’t regulate their own temperature. The best place to keep an orphaned rat is in a small box on a piece of felt large enough to also form a blanket over the baby. (Felt has no threads that can get wrapped around the baby’s legs.) Infant rats can climb better than you might think. Be sure to use a box at least 6" deep, or cover the box so the baby can’t climb out.

Warmth can be supplied by a hot water bottle, a lightbulb, or a heating pad. The important thing is to keep a thermometer next to the baby so you know exactly what temperature he is experiencing. Use a small weather thermometer, not a medical thermometer, as the latter can’t record drops in temperature. Keep the temperature around 100-102 degrees F. Higher temperatures can be fatal.

Use heating pads with extreme care as they can get very hot. Use on the low setting only and place only one end of the box on the pad so the baby can crawl away from the heat if necessary. You may even have to put a towel between the pad and the box to keep him from getting too hot. At two weeks of age you can start gradually reducing the temperature.

Infant rats can’t go to the bathroom by themselves. They’re stimulated to go only when rubbed around the genitals and anus. This is so the mother can ingest the waste and keep the nest clean. Massage the rat’s genital area with a damp cotton ball for several minutes before and after every meal to take care of this important hygiene matter. If you fail to do so, the rat will die of toxic poisoning from his own wastes.

You can clean the baby of spilled food after meals with a damp cotton ball or by dipping him in a warm bath up to his neck and rubbing away the food. Be sure to dry him well. Also give him a full massage after every meal just as his mother would lick him to stimulate his circulation and help him to grow.

The Formula

I recommend using human soy baby formula. The nutritional requirements for rats are closer to that of humans than dogs or cats, and if you look at the information on the components of rat milk at the bottom of the page, you’ll see that the percentage of protein and fat in the human formula most closely matches that of rat milk. Be sure to buy the powdered formula, and the soy formula, not the milk-based formula.

Here is the schedule for mixing the formula (this is especially critical for pinkies):

1st feeding 4 parts water to 1 part powder (eg. 2 teaspoons water to ½ teaspoon powder)

2nd feeding 3.5 parts water to 1 part powder (eg. 1¾ teaspoons water to ½ teaspoon powder)

3rd feeding 3 parts water to 1 part powder (eg. 1½ teaspoons to ½ teaspoon powder)

4th feeding 2.5 parts water to 1 part powder (eg. 1¼ teaspoons water to ½ teaspoon powder)

5th feeding 2 parts water to 1 part powder (eg. 1 teaspoon water to ½ teaspoon powder)

If a baby gets diarrhea, gets bloated or becomes dehydrated, go back to the mixture for the 2nd feeding and progress on from there.

To mix the formula, first warm the water to about 105°F (which will feel hot). It will cool as you mix in the powder and you want it to end up being about 100°F (slightly warm). You can measure out the amount of water in a tiny container and heat it in a microwave for a few seconds, or you can heat a quantity of water in the microwave or on the stove and then measure out the correct amount of water. Then mix in the powder. If you need to feed several babies, you need to set the container of formula in another bowl of warm water to keep the formula warm. A mug warmer (cheap at Wal-mart) is a great tool to keep the bowl of water warm while feeding.

The amount to give at each feeding is 5% the body weight (in grams) as ml. So you multiply the baby’s weight in grams by 0.05. So if a baby weighs 6 g, it should eat 0.3 ml at each meal. (6 X 0.05 = 0.3) A baby who weighs 18 g should eat 0.9 ml. This is critical for pinkies, so you must have a gram scale to keep track of their weights. You can buy an electronic postal scale that will weigh in grams at a stationery store.

Feeding

Getting the formula in baby rats can be a challenge. One of the best methods is to get an IV catheter or small rubber feeding tube from your vet. These will fit onto the tip of a syringe. You will have to cut the feeding tube shorter. The end of the catheter or tube is about the same size as mother’s nipple, but you will still need to slowly squirt the formula into the baby’s mouth. You can also use an eye dropper with a narrow tip. Be careful not to overfill the baby’s mouth which can cause choking.

Another method is to use a tiny piece of rag and form a nipple from one corner. Start by dipping the “nipple” in the formula and squeezing drops into the baby’s mouth. Once the baby starts sucking on the rag, you can drip formula little by little onto the rag with a dropper so you don’t have to remove the nipple from the baby’s mouth.

You must have the rag or eye dropper in the baby’s mouth when it sucks so the baby sucks on the “nipple.” One person tried just dripping formula into the open mouths while the babies sucked, and the babies swallowed too much air. This can be fatal because rats cannot burp. Air bloating the stomach must be sucked out with a needle and syringe through the body and stomach wall.

Sterilize the feeding equipment—including the catheter or rag—every morning in boiling water. Mixed formula can be refrigerated for 24 hours before you need to discard it. Warm only the amount of formula you need to feed by placing it in a small container sitting in a cup of warm water. Do not microwave the formula! Test the temperature of the formula on your wrist before feeding it. It should feel warm but not hot.

Hold the baby upright. You might try wrapping it securely in a tissue or cloth. It may take a while to get the baby used to nursing on the new nipple and the new taste.

Once when I was hand raising a wild roof rat who was just under 2 weeks of age, I thought he hated the formula because he would lick a few drops and then open his mouth as if he was gagging. I finally realized he was opening his mouth to begin power sucking! Infants use their tongue and upper palate to create the suction. Once I got the eye dropper properly positioned he would suck down about 0.75-1 ml in about 5-10 seconds! All I had to do was lightly squeeze the eye dropper bulb.

Newborn rats normally nurse about every 2 to 3 hours. You’ll need to feed your baby every 3 hours during the day and once in the middle of the night for the first week and every 4 hours the second week. Feeding too often will prevent proper digestion.

The Weaning Process

When the baby is a week old he will start to get hair and may be ready to try slurping some baby cereal mixed with formula off your finger (mix it soupy). At two weeks of age, when his eyes open, most of your work will be done because the baby will be able to eat baby food and rodent blocks soaked in formula. At this age you can stop the night and bottle feedings and offer the formula mixed with baby cereal in a dish (a jar lid on a flat magnet works great—the magnet keeps it from being tipped over). By 3 weeks of age the rat will be eating mostly solid food, although he wouldn’t be weaned yet, so you should still be offering some formula. At 4 weeks you can completely wean your baby and congratulate yourself on a job well done!

Special note for Orphaned Wild Rats

For an orphaned wild rat, you need to decide if you want to keep it as a pet or release it. The most common wild rat in California and the southern states is the roof rat which really doesn’t make a very good pet. Roof rats are very hyper and agile and even when tame tend to be very nervous and flighty. I have a male I hand raised and he rarely wants to come out of his cage because he is easily scared. He is scared of everyone but me and sometimes he is even scared of me. I originally wanted to release him, and handled him only to feed him, but he bonded strongly to me anyway because he was an only rat. It is important to have another rat that they can bond to as a baby so they will accept them later. After I decided to keep mine, when he was about 4 weeks old, I introduced him to a young domestic rat and then they lived together. He is a little under a year now and I tried to introduce him to another hand-raised female roof rat and he will not accept her.

In the other states, the most common wild rat is the Norway rat, the ancestor of the domestic rat and they can make good pets if they are handled and socialized enough.

Whether you decide to keep or release a wild rat, it is important to raise it with another rat for it to bond to. If you plan to release the rat, the sooner you get him a companion rat the better because you want the wild rat to bond to the other rat, not to you. You can try to adopt a 2-week-old domestic rat to be the companion (some pet shops sell unweaned baby rats for snake food). You can try to introduce a weaned domestic baby but only bring them together during supervised times to make sure the domestic rat won’t hurt the wild baby until the wild baby is 3 weeks old. Then after you release the wild rat you can get another baby domestic rat to live with the first one. The best thing to do would be to foster the wild rat on a domestic mother or even a mouse. Then you wouldn’t have to handle the wild rat at all.

If you decide you want to keep the wild rat as a pet, then you need to handle it as much as possible. This is especially true if you hand raise a litter of wild rats. Because they have each other to bond to, they will not bond to you unless you spend a great deal of time handling them. In the case of more than one orphaned wild rat, it is probably best to plan to release them. You can release them when they are 6 weeks old. The best place to release a roof rat is an area near a permanent water source, such as a creek, pond, lake, or river, where there are a lot of trees. This is also a good place to release a wild Norway rat, but a Norway rat does not need trees, just a source of water, a place to hide, and a source of food. Some water sources will also be a source of food, supplying fish, frogs, snails, etc.

Rat Milk Components

Range Throughout Lactation (%)

Day Lactose Fat Protein

0 2 - 2.6 20 - 28.6 7 - 8.6

5 2.4 - 3 5.5 - 15 6.5 - 7.4

10 3 - 3.7 7 - 18 8 - 8.6

15 4 - 4.5 9 - 19 8.3 - 10

20 3.5 - 4.7 8 - 14 8 - 10

Rat Milk Summary

Protein range: 6.5 to 10%

Fat range: 7 to 28.6%

Comparison with commercial formulas:

Human Soy Baby Formula—best match

Protein 12%

Fat 25%

Esbilac (for puppies)—too high in protein and fat

Protein 33%

Fat 40%

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