I’m sorry for your loss.
But the dog couldn’t have known he was going to the vet to die.
As for my cat, the vet gave me a price I could live with, and she’s in surgery to remove a cancerous growth. She’s not going to die today. But she’s still clueless how close she came to it.
I think dogs and cats are much more instinctive than people are and more so than we give them credit for. Their instincts are a much more developed sense than ours are. “Clueless” may be the appropriate adjective for people. But for dogs and cats, I don’t think so. I think they know many things that we don’t. But the problem is they can’t speak to us in order to tell us.