I've watched the opening of The Walking Dead countless times, but I can't identify the white-ish animal the crows are eating on the road. My fiancé and I jokingly call it the rabbit/cat/teddy bear.
I'm pretty sure it's a cat. You can't be 100% sure based on the direction of the shot. The animal appears at 0:23 in the opening. I judged cat based on the length of the leg, the tail and fur. but it could be a small dog. It is definitely not a rodent of any kind since the head shape is wrong for it.
It looks like a juvenile cat - it has the foot pads of a cat, as well as the hind leg joints and ears of a cat. It does not have the anatomy of a teddy bear, but it does read a little bit like a teddy bear. I believe this is because it is not a real animal, but a stuffed toy made to look like a cat and filled with something that the crows would want to eat. This would be in keeping with industry regulations for the humane treatment of animals in filming.