There are genetic defects called dwarfs. It happens in German Shepherds.
https://www.google.com/search?q=dwarfism+german+shepherd&lr=&hl=en&as_qdr=all&tbm=isch&tbo=u&source=univ&sa=X&ei=3CB-VJOwNIyrgwSLz4D4Cg&ved=0CCcQsAQ&biw=1680&bih=916#imgdii=_
Just adorable!