Mary, I know exactly how you feel.
When I took Doodles (our cat) in for surgery, they just took her away and never let me say goodbye to her. I was in tears as I was walking out of the vet clinic.
When I took Sneakers and Snowball (chins) in for their dental, I was in tears the entire time. I couldn't stop crying and everyone was trying to comfort me. It's the worst when they're at the vet, you can't be there with them and you don't know what's going on.
But, I'm very happy to hear Angus is doing well.
He's quite the handsome dog!