I wouldn't criticise how the TS treat his/her dog's since he/she made the choice...

Personally, in such scenario, i won't decide to put it down. Second opinion is not enough, what if another wrong diagnosis? i will consult more before coming to that last resort, when you put down, you gave up the chance, you failed to fight until the last minute....

if miracle didn't happen, at least i accompany it till its final breath..

anyway, RIP cookie