Can you mix some KMR into the pureed food? I was told to do this by a feral rescue place when I found my cat at what I thought was 5 weeks but the vet said he was younger. I would doubt they need the heat anymore, do they lay on it? If they don't, then I'd take it out. If they're dehyrated, can you do sub q fluids? Theie bodies soak this in much quicker and it's easier anyway. We do that on the farm for our livestock etc. Right now, since the kittens I'm looking after won't suckle one the bottle, I squirt a little in their cheaks. They're getting the hange of it, they're turning their heads toward the bottle, chewing and sucking every once in a while. They seem to be hungry all the time, they've only had two feedins so far and pee when I stimulate but haven't pooed yet. Also, you need to make the hole a lot larger than it says to in the nipple. I was told this by two rescues as the kittens have to suckle too hard and get discouraged. The one rescue I spoke to said that if the kittens are eating well and 4 weeks plus, age wise, and not already on a bottle, they don't bother, just mix in the KMR with what they're eating. Hope this helps some and good luck... we'll be going through this together since I just got mine tonight. I've never fostered so young. But it was either this or euthanasia tonight. I Hope for the best for both litters.