I know if a dog has liver problems he needs less protein and a puppy or pregnant female need more protein than an adult. I think I have a bookmark on the nutritional requirements, I'll check it.
Nicole,
You seem to be interested in Yorkie's diet. Take a look at this link and let me know if you think I should order this book for $30.00.
Thanks
http://home.att.net/~wdcusick/YorkshireTerrier.html