Prednicare appears to be a steroid so could have the side-effect of causing laminitis and maybe have a detrimental effect on cushings sufferers. I would have thought any vet prescribing both drugs would look into possible contra-indications before prescribing.
Not at the moment, but I have a horse on pergolide who we tried on concurrent prednisolone to treat hepatitis. We used a very, very low dose increasing slowly from 0.1mg/kg to 0.5mg/kg but pulses became raised by day 5, so it was discontinued in favour of azathioprine.
"If an 'alternative treatment' has reliable effect it becomes classified simply as MEDICINE" D.B.