there are puppy lemon laws and ladymom knows the site sorry i do not know but if you search on yt only at very bottom and type puppy lemon laws you can read law for your state. Dogs are considered property so there is no malpractice, etc for dogs but you can collect in small claims court if judge finds in your favor.
There is no genetic marker for liver shunt as of yet but dr tobias at university of tennessee is doing a study on this currently so you may want to contact her in regards to this to get more information.
Some breeders do bat test their male and females though and may not breed one if they find this runs in their line but even people who do the testing the dogs can show no liver issue and still throw a liver shunt puppy sadly
Also I think dr tobias has had two liver shunt puppies bred to one another an not thrown a shunt so the liver shunt issue is pretty complex and they are trying to figure it out and I believe the dink foundation donates money to this research as well as others. I think robin lodel on here with Ginger asked alot about this of dr tobias so you can contact her she is really nice and may have more info as well.
Dr Center and Dr Tobias are the experts on this topica - Dr center is an internal medicine specialist and Dr tobias is a surgeon
Also you can get a wealth of info on this on the two liver shunt groups on yahoogroups.com - one is dog liver disease and other is liver_shunt_mvd group
I am so sorry about your puppy but if caught early and dr tobias does surgery there is usually a very good outcome and it does not have to be a death sentence.