My wide and I do cat fostering. Shadow was one of three kittens we foster, along with his mom. He got ill. We gave him meds and through a hideous mix-up, pills given to help him instead burned and closed his esophagus.
Maine Coon Adoptions, the group we foster for, did everything they could as did their vet, Animal Care Clinic. But in the end the little guy was just too weak and ill and then his esophagus ruptured and his lungs starting filling with fluid so they had to put him down. Damn.
If you wondering what happened, the pill had to be washed down with a squirt of water. Another vet (not ACC) said water wasn’t needed. And that is what killed him.