This tabby cat is one that I embroidered recently, with a technique called thread painting. After stitching the black outline where I wanted it to show, I threaded my needle with three different shades of grey DMC embroidery cotton, a pale, a dark, and a medium grey. Towards the end of the tail where you see the shades are lighter, I used two strands of pale and one of medium grey. Around the rear, I sometimes used two strands of dark and one of medium - and each stitch goes from the unstitched area into the stitched area, in between two other stitches, so that it all blends in together. That is thread painting. The background to this is fabric painting, which is another story altogether. Have you seen my other blog yet? Its at http://bird-diary.blogspot.com/
Hoping to get the website up tomorrow!