rat needs more calories

Question
One of my male rats, (3 litter mates about 2 yrs old), was obviously not himself today and a visit to the vet to trim his teeth was needed. I feel terrible for not noticing his problem sooner as I handle them everyday! I'm looking for ideas how to increase his calorie intake & nutrition while I'm praying he makes a recovery. He has definately dropped weight.  Also part of the day I've separated him from his two littermates to observe how much/little he is eating.  I probably will return him to his regular cage during night, to avoid additional separation stress.  What softer high calorie foods would my rat benefit from?  And would it be best to keep him with the others? Any suggestions would be appreciated.  Thank you!

Answer
Try adding nutri-cal to his daily diet, just offer him as much as he'd like to eat off the end of the open tube. You can also mix yogurt and baby food in with his usual diet to encourage appetite and bulk up on the high calorie, high nutrition treats like fresh broccoli and kale, etc. - just avoid giving him too many high-water-content foods at once, it can/does give them diarrhea.

I would just let him live with the others and try to be sure to feed him by hand a couple times a day, or observe him eating the foods you offer. Keep an eye on his teeth as well - usually once they become malocclused, they need to be continuously maintained by a vet.