I have been told that as yorkies hair is the same texture as human hair then if you keep brushing it with a soft brush and keep it tangle free then the hair will grow naturally. My two are now age 4 and 2 and their hair is growing well now especially the 4 year olds. i do not have their hair trimmed as I show my two but you can always just snip of the end of the hair on a regular basis and this does help to thicken it, but only a very small amount at a time must be trimmed |