Hi
I'm really sorry that you are experiencing such sadness with your Setters.
I think you may find this site of interest with your present problem:
http://www.irishsetterhealth.info/content/porto-systemic-shunts-liver-shunts. I've had Irish Setters for 35 years, but only over the last little while have I lost dogs far too young to sickness. I lost a fantastic girl aged six at the beginning of this year to a cancer a veterinary oncology specialist referred to as genetic.
Have you informed the breeder of the problem with your pup? I would certainly urge you to contact the breed club health co-ordinator, in order for her to record the problem.
Very best wishes, to you and your pup.