Have you noticed any muscle tremors, weakness or other neurological symptoms/signs? Or any hair loss or skin issues? My Cane Corso mastiff was diagnosed with Addison's disease back in the fall; he'd been sick on and off for about a week (legthargic, no interest in food, etc.) and the night before his vet appointment I came home from work to find that he could not support his own weight
I rushed him to the vet and after a looooong overnight in the ER and some testing he was diagnosed with Addison's.
It's been a long road since then (in large part because of his size, figuring out the dosages has been a challenge), but he has been doing pretty well over the past couple of months now that we have his prednisone and percortin injection dosages where they need to be. Turns out the skin issues, hair loss and the muscle tremors he'd been having since I adopted him were all related the Addison's as well, but have improved! The good news about Addison's is that if managed properly, most dogs live a normal, happy, healthy life!
I'd LOVE to hear what your holistic vet has to say for additional adrenal support, if you wouldn't mind keeping me posted?