Vetinary mistake has lead to my dog on its death bed and $15k+ in debts

I'm emotionally exhausted after the last 24hrs. So forgive me if this is poorly written.

My Pomerinan was itching at his privates yesterday morning, so We took him in to our vet.

They went to check his bladder with a test, and it appears they missed and nicked a blood vessel causing internal bleeding or he had what sounds to be a 1/100000 allergic reaction. (The knick seems to be the obvious cause, they just wont say 100%)

So they urgently transported him to the hospital where they needed to do a blood transfusion, and then another 1/100 incident occurred causing things to worsen and fill his lungs with blood.

So we were left with him coughing up blood from his lungs, and the choice to watch him struggle in pain, put him down, or pay $15000 for ventilator support.

There's still a slim chance of his survival now, and I'm willing to do anything, but financially we are running out of money, and being on the ventilator costs near $6k a day.

Our vet waived the charges for the incident on their end (about $700), but we are only here because of their mistake. Is it possible to bring legal into this to assist? I'm afraid we won't be able to act fast enough, but either way this is a financial blow that will set us back.

20 hours ago he was a happy and healthy dog with an itch, now he's likey on his deathbed.
Can the vetinary office be held accountable in any way?

If so, would searching for a certain kind of lawyer be beneficial? I just want him alive, and the byproduct that is of course money, as all things are in medicine.