I have never thought of a stuff animal for Piglet. Thanks for the idea.

If she is genuinely cold, after consulting with a vet, you might try a heating pad. We have one for our cat and he really enjoys it. they come in various sizes and most will automatically shut off after a time. The low setting is just barely warm, which should offer comfort to a guinea pig without overheating. Please let us know what the vet advises. If you can't get Piglet to a vet you might check on line. I didn't see much information on PetMD but thre are other sites. Good luck.

Is the Guinea Pig inside? Remember their natural habitat is the Andes in Peru.

I had Guinea Pigs for many years. They lived outside in a huge cage with plywood sides on the West Coast of Canada, it does freeze here in the winter, but not nearly as cold as it gets in Michigan. I would fill the cage with Alfalfa and they would snuggle down. I also put a blanket on the top and open end in really cold weather.

If the pig is inside, just give her something to burrow into, a show box works well and can be replace for free. Cut open one end. My grand father made mine a plywood house, when he built the big cage. They chewed around the edges of the plywood, but that did not cause any harm.

Guineas are chewers and I would not put anything in the cage that was not digestible.

Don't put anything in the cage that is electrically powered! She will chew on it. No doubt about it. I know they make electric stick-on heating pads that can go under a cage, on the outside.

Also, I would be hesitant to put any rice filled items in a guinea pigs cage...if she chews thru the outer fabric and has access to the rice itself, it might do her some harm. Their digestive systems were not built for rice.

She has this wooden house inside her cage that she likes to sleep in. I am thinking about lining the inside with fleece.

As others already mentioned ... Piglet could start chewing the fleece?
and then ?????? :(