We didn't put Jake down.
Turns out the vet sucks and he doesn't have debilitating arthritis in his hips at all. He has a torn ligament in his knee and it can be corrected through surgery.
I'm glad he's alive, but I'm very upset that he's been injured for 2 years and we haven't been doing anything about it.
Grrr....stupid vet.
Needless to say, we are now going to go to a new vet...the same vet we took Gigi to b/c he's awesome.