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Mice/How much should a baby mouse weigh?


My friend gave me six baby mice, knowing that I was an animal lover; she had found them in the glove compartment of her car. She had no idea what to do with them because she obviously didn't want them inside her vehicle, so I took them in. I suspected they were newborns as they looked like it. They did excellent for the first two days and on the third day (today) 4 of them passed. I have a scale in which I weigh my babies to make sure they get enough formula each feeding, but last night, all my babies started loosing weight almost immediately and then passed. Currently, I have a baby at 1.7 grams and a baby who is at 1.3 grams but has a full tummy. The baby who is 1.3 grams used to be 1.5. I want to know if these weights are okay and how will they gain weight? I have been feeding them every 40 minutes because they now seem to lose weight even easier than before. They both have obviously full tummies, but I just want to make sure I am doing things right. I don't want to lose these two. Thanks so much!

Hi Alia,

Their weight will depend on their age and condition, but they should definitely weigh more than that, especially given that we know they are at least 3 days old. Any drop in weight should be considered an emergency, so given their inability to gain on a normal diet (I'm assuming you are giving some kind of formula?), their best chance at survival is to see a veterinarian who is experienced with orphaned mice, or a wildlife rehabilitator who also has experience, right now.

If you can't find anyone who works with rodents on your local wildlife and forestry website, or amongst local vets, you can also try rodent breeders, pet shops, or rescues to see if anyone can lend you a helping hand. It's possible they did not get enough colostrum before being transferred to bottle feeding, or are dehydrating as a result of the transition. Either way, they need be gaining every single day, and you should be able to see an upward progress each feed.

Best of luck,


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I can answer questions regarding mice as pets, mouse behavior, color and coat genetics, breeding techniques, and general health questions. I can help with caging and setup, nutrition, social issues, and what to do in most mouse emergencies (such as unplanned litters, injuries, fighting, etc.). I can also assist with questions pertaining to orphaned mouse pups, weaning litters, and questions of mating and birthing. I cannot answer questions about exotic or wild varieties of mice such as spiny or pygmy mice. *****FOR EMERGENCIES, anything requiring immediate medical intervention, PLEASE take your mouse to a professional veterinarian or wildlife rehabilitator who works with mice as soon as possible! IMPORTANT RESOURCES: Raising Orphaned Mice: Orphaned Mice Videos: Natasha's Your First Mouse: General Mouse Help: Mouse Info and Exotic Breeds:


I have enjoyed the companionship of mice nonstop since 2004, and spent a year caring for them in a lab where I learned a great deal about their breeding, social needs, and health. I spent a few years breeding them, specifically working with albinos, marked mice, angora mice, and satins. My education never stopped - I am learning something new every day from current and well-established research thanks to the wonderful folks at the Jackson Laboratory, as well as from my wonderful mousey friends online. I also love learning from my terrific questioners here on AllExperts - you folks keep my passion for these amazing animals alive and well!

East Coast Mouse Association - expired, American Fancy Rat and Mouse Association - expired

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