Some kittens and older cats have a bad habit of chewing on wires and cords. Does this sound like your cat? If so, don't bring an electrically-heated bed into the house; it's just too dangerous. If a self-warming bed isn't providing enough heat for your little one, consider buying a microwaveable heating pad like the one created by . Follow the instructions carefully to make sure the temperature is suitable for your cat and check the pad yourself to double-check.
Top Best 5 heating pad for cats for sale 2016 : Product : BOOMSbeat
As far as your Momma feral cat being O.K. - from what you've already said, it sounds like all her needs are being met. You're providing food, clean & fresh water & have a good main shelter (covered screened porch) with a smaller insulated shelter (feral villa) with a heated pad. Just keep in mind that some feral cats won't ever want to stay inside. There are many reasons for this...some of them being - being outside, on their own for a long time period and/or having bad human experiences they don't trust enough or are uncomfortable being inside for long periods of time.
Winter Pet Heating Pad for 'Boots' the Cat - YouTube
Hi! I have been caring for a feral cat for about 3 years now. One of the things I did for those of you on a limited budget was buy a big plastic storage container with a lid. I cut an opening on the front of it for him to go in and out. I lined the container with egg crate material, sides and the bottom and put a heating pad in the bottom of it with a light layer over the top. I keep the heating pad on low. Or you can buy a pet mate heating pad that always stays on the right temperature and it also stays on 24 hours a day. This way your cat has a roof and insulation. The heating pads work great too. Just don't turn them on to high.
Winter Pet Heating Pad for 'Boots' the Cat
The Heated Cat Pad is a comfortable indoor sleeping pad you plug into an electrical outlet to help your cat stay warm. The Heated Cat Pad can be used alone or placed on top of your cat's bed. The heating pad found inside is also removable which makes it great for year-round use.Heated pads for cats are a good choice for your home because they are very safe and require little electrical power to use. These pads will not heat up past a cat's body temperature, meaning that the risk of their catching on fire or overheating is very small. This also means that you can safely leave a cat's heating pad turned on for extended periods of time while you leave the home without having to worry about the safety of the pad, of your cat, or of the house.