American Fancy Rat & Mouse Association

This article is from the Summer I 1998 AFRMA Rat & Mouse Tales magazine and is in the AFRMA Breeding Book. See the AFRMA Breeding Rats & Mice, Care and Guidelines book for more on orphans.

For those that take in orphan wild rodents, there is the possibility of them having parasites or diseases that can be harmful or fatal to other pet rodents or humans. Care must be taken when dealing with them.

Caring for Rat & Mouse Orphans

By Karen Robbins

This mouse (the light one) was fostered onto a rat two days after her mom died. The rat just happened to have this litter born the same day as the mouse. The baby rats considered her their sibling. Photo ©1993 Craig Robbins.

Occasionally you will find babies who have lost their mom. The best thing to do is to try and find another nursing female with babies the same age and a small family of her own so she can accept the foster babies. If you do have another mom able to accept the orphans, take her out, take all the babies and rub them all together in your hands so they all smell the same or place the new babies in with the others and roll them around and leave for a few minutes or rub a bit of soiled litter on the new babies. If you are unable to find a foster mom (you can put orphan mice on a nursing rat mom and vice versa; rats are excellent mothers and will nurse about anything), then you can try feeding them yourself. However, your chances of successfully raising newborns are not good. If you do try to nurse these little guys yourself, you will need to feed them EVERY 2 hours, so be prepared for some sleepless nights.


As far as a formula to use, many people have used different ones to their advantage. Whole, raw, fresh goat milk; KMR® (Kitten Milk Replacer); Esbilac® (puppy formula); Enfamil (without iron); or Soyalac human formula have all been used. The powdered formula is usually used rather than the liquid as you can mix up a fresh batch each day and the powder will last longer. The liquid formulas have to be used within 3 days after opening. Lambert Kay™ makes a Mother’s Helper™ puppy formula that can also be used for rats and other orphan babies.

Rat & Mouse Milk Facts

in order of fat amounts
(in percentages)
Powder Formulas
Esbilac® puppy33.
Just Born® puppy29.
KMR® kitten40.
Just Born® kitten33.518.
Liquid Formulas
Just Born® puppy6.
Esbilac® puppy4. 
Mother’s Helper™ puppy4.
KMR® kitten7. 
Mother’s Helper™ kitten7.
Just Born® kitten7.
Goat Milk3.0–3.63.8–4.1 87.0 

Milk Constituents In The Mouse
(in percentages)
Total Solids29.70 +/- 0.64
Crude Fat13.20 +/- 0.95
Crude Protein9.37 +/- 0.35
Lactose2.25 +/- 0.11
Crude Ash1.08 +/- 0.05
Calcium0.18 +/- 0.05
Potassium0.26 +/- 0.00
A higher percentage of total solids including fat, protein, calcium, and potassium but a lower lactose percentage was obtained in mouse milk compared with the milk of some domestic animals (cattle, sheep, goats, and sows).

Rat Milk
Total Solids27% (73% water)
KMR (Kitten Milk Replacer) contains about 18% solids (82% water). The solids are 25% fat, 42% protein, 26% carbohydrates, and 7% ash. KMR has less than half the fat content of rat milk which is the major energy source. Newborn rats do not have much energy stored, so need the higher fat content in the milk.


A baby bird feeding syringe with a fine curved tip or a very small doll nursing bottle will work as a nurser. You can also use a piece of absorbent string, acting like a wick from bottle to baby, for the very small ones until they are big enough to grasp the bottle tip itself. Another idea is to take a piece of small plastic tubing (strip the plastic tubing off a piece of wire—22 or 24 gauge for mice; 14 to 20 gauge for rats) about ½ to 1 inch long. You can then insert this tubing into your syringe or nipple of a nurser bottle. Four Paws® makes an Easy Feeder™ Hand Feeding Syringe For Small Animals that has two syringes in the pack—one with a nipple tip and one with a tapered tip. The tapered tip syringe has an opening equivalent to a size 12–14 gauge wire tubing. The baby bird feeding syringe has a tip equivalent to a 22 gauge wire tubing. Also, you can get a gluing tip from a hobby/beauty supply store. Heat up the tip and slip it on the syringe. This will “glue” it to the syringe.

Feed small amounts at each feeding, being careful not to get any in their lungs (if you see milk bubbling from their nose, it’s an indication some is getting into their lungs). Always feed warm (not hot or cold) formula to your babies.

You can tell when their tummies are full by the white patch in the left middle of their bellies (do not over feed). It will take about five minutes to feed each one.

. . . you will need to feed them EVERY 2 hours, so be prepared for some sleepless nights.

Don’t be discouraged if they appear smaller than others their age. This is common with hand-raised babies. Sometimes they will even lose their hair for a short time, but it will eventually grow back.


After you feed each baby, they will need you to massage their abdomen and rectal area with a warm, damp cloth to stimulate them to urinate and pass solid wastes. You will need to do this until they are eliminating on their own. Remember to always handle these guys carefully as they are very small.

It is very important to keep these little guys warm at all times. Many people use the plastic critter carriers lined with a towel and either a hot water bottle under the towel or an electric heating pad (set on the lowest setting) with the carrier placed on it. (The temperature of the nest should be between 75°F (24°C) and 90°F (32°C).) This makes it easy to take them with you to work or school to feed them on their schedule.


Diarrhea is one problem you may encounter when feeding these small rodents. The main cause is over feeding. Another cause can be coccidiosis—a one-celled internal parasite that can be diagnosed by your veterinarian. Dehydration occurs with diarrhea no matter what the cause and can kill the babies if not treated promptly. You will need to stop giving all milk to your orphans and replace it with the same amount of electrolyte solution for human infants. Milk will irritate the digestive tract and prolong the diarrhea. Your babies will need, not only the fluids from the electrolyte solution, but also the salts and chemicals it contains. It will often be necessary to also give a few drops of kaolin-pectin every 2 hours to help halt the diarrhea.


Once the babies open their eyes, you can start adding dry baby cereal to their formula (make sure it will pass through the tip of the nurser) as well as cutting down on the nightly feedings. You can start to wean them off the bottle and onto a dish when they are about 3 weeks old. Dip your finger in the gruel mixture and let them lick it off your fingers. Decrease the amount of bottle feedings and give their meal in a small dish three to four times a day. You can start to add different things like oatmeal, bread, lab block powder, and baby food to their mixture. Also by this time, they will start to nibble on bits of apple, carrot, fruits, seeds, etc. Make sure fresh water is also available at all times as they will start to drink from a bottle. Give fresh meals each time, taking out any uneaten foods. You will also need to clean them up after they eat as they are very messy eaters. They can lose their coats and go bald temporarily if they are left dirty.

With lots of love and a proper diet, your babies will grow up to match their relatives in size (they will outmatch them in temperament though!).

If your babies made it this far, you will have some exceptionally wonderful pets as they see you as mom and have strongly bonded with you. You should feel very proud in raising these very difficult babies! With lots of love and a proper diet, your babies will grow up to match their relatives in size (they will outmatch them in temperament though!). *

Some additional information on raising orphans:

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Updated January 10, 2023