After looking at the photo again, I believe I would use one of the light colors to make an "inner" border to sort of "end" the the animal's nose and other parts. I may be wrong, but it seems to me that using a darker border will look like his nose is against a wall. I would "try out" a beige (or other light color) as an inner border (even 1 inch finished) and one of the blues as an outer border.
bkay