I still don't understand because I have two rats in the same cage, so they eat same food, (Nutriphase with enough protein and plenty nutritional sources) and the other healthy rat, Buttons could have gotten lice or mites too but he looks great. and no, I haven't seen him stratching more than usual. I fill up right after the food is gone. water dail, of course. another thing, yes Zippers probably react differently from Buttons however, I've not changed any bedding (carefresh) or food (nutriphase) for almost a year, there's no better product than those! how "too much" protein is it to you?