Absorbing every part of a meal?

So roughly 6 days ago I fed my approx 300g male an adult mouse f/t. He took it and I was excited! Well, last night he laid a urate smaller than a thumb tack and soaked the paper towels. He usually won't eat until he's pooped, so I thought what the hell. Thawe out and offered another adult mouse and he took it too.

I know the meals are small, after his explosive diarrhea episode I didn't want him developing a refeeding syndrome so I have started him out small and have moved up. I've got one more adult mouse before I go to weaned rats or small rats.

Do you think absorbed all of the mouse since he went so long without a meal? Or is he just holding it in and really had to pee (lol)?

Their poop can be pretty nasty when they've been holding it or a while. I would still take a fecal sample in to the vet to check for worms to be safe.

My 300G Pied girl can go weeks with out pooping then will sometimes poop after 2 feeding in a row I think they poop when you clean the cage I am sure :p And yes I would take a fecal to the vet just to make sure he doesnt have a parasite