My wife has worked in the vet field for years and the best stuff we have found is Eco 88. It breaks down the enzimes of the stains and smells like the stuff they use for cleaning up crime scenes and such. The guys from mythbusters used some stuff like it when they locked up some dead pigs in a vette for a few weeks.
Go down to your local vet and ask for it. You may have to try a few diff places till you find it. Not cheap, but well worth it.
Nothing really amazing about the stuff, but its the only enzime cleaner I've seen readily available to the public. We have 2 dogs and 2 cats. Use the stuff all the time and it works great.