Didn't open this thread until now - my goodness, I am so sorry for you
I'm lost for words from the shock and grief, but want to say, at the very least, that it's not your fault. Every time anyone takes their dog out, off leash, on leash, for a car ride, for a hike, etc., there's no knowing what happens, and life wrapped up in a protective bubble isn't much of a life for a young dog. You gave Classic a great life and did what was right for him in the end. I'm giving Trent an extra kiss on the nose and ear rubs tonight, and thinking of you and Classic.
Hugs for you, Zuma, and Zinga.