My lab / rott had similar symptoms when he was just about 2 years old. Took him to the vet and found out he had Parvo. Apparently this is like the black plague for a dog so the vet gave us the same option $1200-2500 surgery and extended vet stay (about a week and a half) adding up to about $3500 after it was all said and done and even then there was a slim chance of survival.

At the time my wife and I were pretty young (23) and absolutely flat broke sharing a car and working as peons but we went for it anyway... visited him every day in the hospital... he survived the bout and lived to be 14 (he died 2 years ago) he was a great dog and is still missed but we sure are glad we took the chance.

A few months after the surgery and everything we were having a party and my sister-in law brought over her new room mate that was an assistant for our vet, he told us "None of us thought that dog was going to make it man, I think your visits pulled him through".