I need a small computer to tally 48inch wheel distance

I have a 48 inch wheel that I would like to keep a running total of the distance that the wheel travels each day. The wheel is stationary and is used in animal research. It is a stationary treadmill of sorts and I would like to know the distance the animal is going each day. I would use a standard cycling computer, but none of them will compute a 48 inch wheel.