Need help isolating object against alpha channel

[sayluv]

Hi-

I am trying to isolate my dog in my project but I forgot to add the alpha channel. I tried creating a new image so I could select and past the dog in but when I do a fuzzy select I cant get it to select the dog or the white so that I can invert it.

Thx

Gimp File: http://www.filedropper.com/01-09-19bholu...prosthesis