Weaning sick baby mouse

Question
QUESTION: I have two female mice who had their pups at roughly the same time. They raised them together and right now they are at the stage where they've started eating solid foods. They are energetic and healthy, and I've handled them daily as recommended, as they're being raised as pets. Right now they're considerably tamer than their mothers, who were from a pet-shop.
However, one of the pups worries me. My cat stole him from the tank about a week and a half ago, and although she didn't kill him, he was injured by the time I managed to take him away from her and back to his mothers. He recovered from his injuries, but he has stopped growing since then. When I noticed he wasn't strong enough to fight off his siblings when nursing (with twenty healthy siblings, feeding time gets rough for him and he can't always secure a nipple), I started complementing his diet with formula at regular intervals, but he never drank more than one or two drops at a time, despite being noticeably malnourished.
While his siblings are the very picture of health, he is skinny and weak, and he spends most of the time sleeping. He hasn't started eating solid foods and he is about half the size of his siblings. He hasn't even fully opened his eyes yet, while his siblings did that about four days ago.
The problem is, soon I will have to wean his siblings, and while his siblings can eat on their own by now, he hasn't even attempted to do it, and I'm not sure what I should do. Should I leave him with his mothers in the hopes that he will recover better that way, or place him in a cage with the rest of the males?
I don't hold high hopes for his survival either way. I've considered euthanizing him, but he doesn't seem to be in pain, and although his unkempt appearance and his severe lag in growth suggests he may be dying, he is still rather energetic for his size, and very tame. He seems to be struggling hard to live, and I didn't want to take that away from him...


ANSWER: Dear Jennifer,

Leave him in the cage with his mom.  If she has another litter, he will be able to continue nursing if he needs to-- with smaller competition.  The only reason to have to take out boys is so they don't mate with mom, and this one doesn't sound like he is going to do that.  Don't remove him until he appears healthy and can stay warm on his own.  You will never be able to put him with other males.  Keep him as a special pet.  With all the attention you have been giving him, he may be the sweetest mouse you'll ever have!

squeaks n giggles,

Natasha

---------- FOLLOW-UP ----------


snoozing   QUESTION: He is indeed a very sweet little boy, and I grew overly fond of him... despite the fact that I wasn't planning on keeping any of the pups, I ended up getting attached to him. When you've had to get up several times in the middle of the night to feed a few drops of formula to a baby mouse that is smaller than your thumb, it's kind of impossible not to love the little guy...
I even named him! He has a small mark left where my cat bit him, so I ended up naming him Brandy... (mark = scar = brand. Brandy!) He almost seems to consider me a third mom (he already has two, why not a third one?), judging by the way he behaves when I handle him. He almost invariably ends up falling asleep in my hand after I've fed him. :3 (and I caught him confusedly looking for a nipple in my finger a couple of times. XD)
The thing is, I'm a little bit worried because I wasn't planning on having my mice have any more litters. They came pregnant from the start... if I got a male and crossed them, how long would it be until my mouse could nurse again? (since I suspect her milk is drying by now)
And if that isn't an option, I've heard something about fostering baby mice to a new mom... how would that work?

Answer
Dear Jennifer,

He doesn't necessarily need to nurse-- it would take too long for the mom to have milk again if you bred her for that purpose.  And I'm afraid in his condition another mouse would not take him in.  You will need to feed him with the formula (KMR is best) for a while yet, getting him onto fromage frais, yoghurt, and some bread soaked in the formula as soon as possible (of course these things spoil fast-- only two hours in the cage).  He will probably lick any of these happily off of your fingers.  If he is too skinny, condensed milk is highly calorie-laden.  For more nutrition, baby food or homemade pureed vegetables could be good, maybe mixed with the yoghurt.  Starting on seeds isn't the easiest way to begin solid foods, so you could give him raw vegetables and things he can chew more easily, then crackers, then seeds. I'm sure you can be creative.   He's a lucky little guy.  I wish him the best <:3  )--~

squeaks n giggles,

Natasha