We can absolutely sympathize with you and your family. Have had to have our share of family pets/hunting partners go to the “big bird fields in the sky”. Hurt for you just reading about this. It’s not easy to do the right thing by your best friends but it’s what they would want I believe if they could tell you.
He told us. He gave us “the look”, and it broke our hearts. My last dog did that too. It’s a look that says “Sorry guys, but I’m done. You will have to let me go. I don’t want either of us to have to do this. I will miss you, but it’s ok.” That’s as good of a translation as I have.