We lost our first rat, who was also our heart rat, to PT. We spent time we should of had with him trying (begging) vets to give us the medication we needed. We went to 4 or 5 before we found the one were at now, but by then it was too late and we had him pts. It was devastating and we had his son pts at the same time (kidney failure). I never thought such a tiny fur balls could make me feel such loss. I still miss them and cry over my boys, but the pain and heart ache does get much better.
Don't ever second guess the treatment you got him. You did the best you could with what was available to you. Its not your fault the vet wouldn't listen. Moose knew/knows how much you loved/love him and he knew you were doing everything you could for him. Grieve however you like cry, scream, throw things, write a nasty letter to the vet that failed you - I did all the above. We all understand...