We have just got a five year old male boxer from the r.s.p.c.a kennels .Two things concern me .One is when he has rested for a while he seems to have trouble walking could this be due to the amount of time being locked up in the kennels or is another problem.Two he is very thin and we were told this was down to kennel stress .We are feeding him three times a day on a high vitam dry food which was the same he was given at the kennel.Do we need to give him any thing else or will he begin to put weight on by himself.This is the first boxer dog we have kept although we have kept other dogs .NOTE We have had the dog for five days