Many people use homemade rice packs to warm kitty's ears prior to BG tests but I found them to be problematic. Hot spots. Difficult to regulate heat levels. And they give off moist heat which could potentially burn kitty's nasal passages if he tends to like to sniff everything that comes near him like my kitty does. Ok, so I'm the one whose nasal passages got burned once when I sniffed them coming out of the microwave. I found these gel packs on Amazon that are perfect. They perform double duty of heating kitty's ears as well as your hands if you are like me and your hands turn to ice in the winter or when you get nervous. They come as an 8 pack so you have extras if they get punctured or wear out. Pop one in the microwave for 10 seconds. Take it out. Give it a little shake and stuff it down into an old cotton sock or footie or mittens if you have them. Then gently massage kitty's face and ear or use two to make an ear sandwich. After a couple minutes the ear will be nice and warm and ready to prick.