Alright, I think I know what's going on. I don't believe it's the coding, but the mesh. There appears to be something that looks like an artifact on the paw of the feline model which causes this problem; this issue isn't present on the canine model.
I don't know if it's fixable, but I'll try to find what the UVs are for this portion of the paw and let you know if you can fix it by erasing them.