Awww poor poppy.... My gypsy did the same thing when she was just 10 weeks old, we tried to splint it and wrap it as because she was so young we were hoping that we could 'mend' it and encourage it to grow straight, unfortunately after a couple of weeks doing this the tail became painful where the break was, we took her to the vets again who confirmed that the bone was starting to push through the skin at the break and that the tail would have to be amputated. We asked them to save as much of the tail as possible and now she is fully grow it is probably about 3-4 inches shorter than my other cockers.
I totally understand your devastation, I was beside myself with guilt, even though we have no idea how she did it, mixed in with panic and worry about my then 12 week old pup have an anaesthetic and painful op.
When we collected her they had placed a plastic tube around the tail and thick padded bandages over that, we went back after a week for removal of dressings and the tail had healed quite well although was a little guey so vet said best to leave it open for the air to dry it out, which we did. The most heartbreaking thing was that for a couple of days everytime she wagged her little tail it hurt and she would yelp and run away from whatever was making her happy enough to wag her tail. She was so confused about why happy things hurt and I felt powerless to help.
However there was light at the end of my long tale ( pardon the pun) when it did heal after a few days she was fine, and she is still the most beautiful cocker I have ever seen, everywhere she goes we get stopped to admire her. She has a beautiful long coat and gorgeous shape and pretty face that no- one ever notices her tail till I tell them.
She's now 15 months and to us her tail is part of who she is and what she's been through in her life and I wouldn't have her any other way.
Lots of love and positive thoughts to you and your baby from Lucy and the naughty cockers Ebony, Gypsy and Gracie bear xxxxx