First I have to ask how old are they? are they loosing weight? what is their current weight? I have only done this a few times. But I never assist feed anything bigger than a pink just my preference. Second I have had one that when I place the head of the P/K pink in its mouth it would constrict and eat no worries. then I had one that I had to get the rat down it throat before it would swallow it. Again its just based on what you animals will do start by just trying the placing it in the mouth thing. Then move on.