the link below will show a sewout of a cat using running stitches to create the fur and different shades of thread were used over a base color fill
http://www.zshare.net/image/272970669cd8d6/
I also did a tiger using a shading effect, and again for the markings a running stitch for detail.
http://www.zshare.net/image/2729831b10ea2a/
