Blending animal pictures with different color schemes

Hi,

As part of a present for my girlfriend's birthday, I'm trying to photoshop pictures of her dogs on to pictures of foxes.

I'm having trouble finding a good way to blend the color schemes so that the color on her dog's fur lines up with the color on her dog's fur in a natural way.

See attached -- particularly the black dog on the right has black/white fur, and most fox pictures have redish fur. Is there an easy way to match up their colors? Seems like there should be, but I haven't been able to figure it out with some playing around and googling.

Thanks! (See attached for the picture I'm trying to photoshop)