A while back I read a website about preventing respiratory flare ups in rats because mine get sick a lot and need antibiotics. On the website it mentioned a vitamin I can give to them in drop form. I believe it said give one or two drops a day for one week on and then two week off. I thought it was vitamin E but I'm not sure and I can't find the website again. Is that something I can give them or do you know of a different vitamin they should be getting extra to boost the immune system? I saw echinacea is good but does this come in an easy way to administer like drops?