I had to do it by making the selection with the brush: I "coloured" around the silhouette (which is not clear at all, as you see, due to all that fur X3) on a new layer, using the standard Photoshop brushes (so I could decide where to feather or refine the silhouette). Then, I picked the selection from that layer and filled new layers with pattern/gradients.
It's not too difficult if you try ^_^ Tell me if my explaination is not clear (and this could be because I'm italian XD)
When she was a little puppy she looked like an angora, she had very very long hair. But when she grew up the lenght of her hair remained the same so now it looks normal X) I should have photos of when she was a little furry ball *O*