My mare had IRAP in hind fetlocks for mild OCD, and it seems to have worked, although apparently her blood clotted funny so we have less treatments for the amont of blood taken.
Quite expensive but if it does work might be worth a try. She was back in work within a week - although let her tell me when she was ready to step up the work.
My mare had irap for ligament injury as I was told it was her only hope. Unfortunately it hasn't helped my mare at all but her situation is very different froma tendon injury. As a therapy it has had fantastic reviews and some amazing success stories but an definate outcome is often guarded as it is still quite a new treatment.
Generally though it is defintealy worth having done. all the studies I read on it were favourabe.
I think, it is for muscle injuries and osteoarhritis treatment.
Unfortunately, we still dont have a magic formula for tendinitis treatment.
a horse owner tried stem cell treatment here (in Turkey). Result was unsuccessful. I think, best drug is time