Mice/Orphaned baby mouse
Hi. Yesterday I found, in a plastic storage tote, in our camping trailer, an orphaned baby mouse, along with some already dead siblings. I did a little research online and have him in a plastic box (in the garage, I have cats) with air holes drilled in, on top of a heating pad, with paper towels inside. I've been feeding him a homemade formula from a paintbrush every 2 hours, recipe courtesy of Creek Valley Critters. It, Buddy's (though I'm unsure how to determine the gender). eyes are open and he has fur, he is about 2 inches and weighs 4.5 grams. Last night I removed 2 reddish looking bugs I noticed (and was able to grab with tweezers)from his head/back. I am unable to bring him to a vet, so I don't really know what to do about that. He scratches a bit here and there but I haven't seen anything since. He's very fidgety when I try to hold him for feeding, but he's taking the feeding better now. He definitely doesn't like me rubbing his belly or behind, so I've been a little lax with that, though I do do it a bit. He seems able to clean himself (especially using his hands to wipe around his mouth, eyes and head, though I clean his mouth with a q-tip after feeding. I guess I'm wondering how old you might think he is?! when I might try to start feeding him more 'solid' food and water?! why does he try to eat my gloves?! how I can be sure of his actual gender?! If I can eventually let him back into the wild, or how I can find him another possible caregiver?! What if I don't do anything about the bugs?! Also, I will be going away for the weekend, and plan on taking him along, any thoughts on how to make a long ride in a vibrating truck more comfy for him?! Thanks.
I'm going to try to answer all of your questions, but if I miss anything, please let me know!
I can't identify what the bugs are without more information, and even then, I couldn't do as good of a job as a vet. If you can see the bugs, they are probably not mites or lice, which is good. Remove any more that you find, but chances are they probably hopped on in the trailer and aren't actually dedicated pests. Unless the situation changes, you do not need to do anything else about them.
That's a great size for a young mouse! Continue to weigh him several times a day. As long as he is gaining weight consistently, he is doing well.
If his eyes are open, he is fully furred, and he is mobile, he is also *probably* pottying on his own, which means you won't need to rub his genitals or butt. Check the bedding, though - are there pee spots and little poops? If so, you do not need to potty him. If not, he will need help with going to the bathroom at every single meal. Rubbing his tummy is more about controlling gas pains. If he is not having any stomach upset from the switch to formula, then this step is not as crucial.
I cannot guess his age without a photo. It sounds like he is at least 10-14 days, but I can't really guess anything for sure from just a description.
You can start offering solid foods to practice eating as soon as he is mobile enough to explore them, so probably now, based on what you've told me. Try a little stale bread and some commercial mouse mix (blocks or pellets, not seeds/corn). As far as water, you can offer water via water bottle right now. He may not use it until he is 4-6 weeks old, though, and until he does he will continue to need formula for hydration. Make sure it is accessible to him, but not low enough that it leaks or jams and floods his bedding, which could chill him and can be deadly. You may consider getting him a cage like a tank for this reason, as well, especially since heating a closed plastic container (even with air holes) can become too hot or humid quickly. Be cautious of cages with bars, however, as wild mice are master escape artists and can get out of ANYTHING they can fit their heads through.
It might be tough to tell the gender now that he has fur. Here is a guide with pictures that may help you:
As soon as he is eating and drinking on his own, he can be released. Wild mice do not forget how to be wild, even if they are hand raised. At that point, you can take him somewhere far, far away from your camper or other locations where mice are not wanted, and release him somewhere with bushy cover. He will know what to do!
Is he biting you or trying to chew on them? If it's the former, that probably won't stop. It's instinct to try to defend oneself from perceived predators, and people are much, much bigger than a mouse. If it's chewing, he may be ready to try some solid foods!
Road trips can be pretty stressful to any animal. Be careful of on-the-trip feedings so you don't drop or lose him, and make sure you have all the supplies you need to provide care. Other than that I don't really have advice - it's hard, but it's also hard to find a sitter for such a fragile critter.
Hopefully this helped! Let me know if you need anything else.