I'm so sorry for your loss also. Your pup was so cute. I have to agree with Marko that he was likely just at a point where nothing was going to change the course of his life or death. If you truly feel your vet failed you then you will likely always second guess him and I would recommend changing vets in the future. I doubt there would be any way to hold him responsible even if he did make an error, but as you said you don't doubt he was trying to help your pup.
I'd try to put it behind me and know that you gave your boy the best life possible and move on. I don't mean that to sound harsh, sorry if it did. I just mean continue with your grieving and hold his memory dear. Remember all the wonderful times you had with him. He's pain free now and beating yourself up with questions isn't helping him or you. One day, another lucky pup will fill your heart again.
