Had a few in clinics that were horrible... dog on three different pressors with BP still in the tank, in multi organ failure, on fentanyl CRI, doing that awful death cry/whine... we had to watch the dog go downhill for days prior. Sat with it all night and it died early the next morning...took everything to get the owner to change the CPR status from do CPR to DNR...
Another one that still haunts me... Dog having blood pouring out both front and back ends, lateral, pale, PCV is in the tank, needs transfusion, diagnosed with GI lymphoma, dog is going downhill fast. I spent all day sitting with him cleaning up his crap and bloody vomit just so he wasn't laying in it. Owner refused anymore treatment/testing/euthanasia and wanted the dog to pass peacefully at home. Home was 3+ hours away, we all knew dog wasn't making it home, we explained that to the owner, she didn't believe us.... dog passed away in the back of the SUV on the way home...owner didn't make it even 30 minutes out of town.