Hello Stanley and thank you for your question.
Before talking about Cushing's , it is necessary to highlight the disease through a blood test that your vet will practice.
Depending on the results, your vet will prescribe a treatment adapted to your horse.
if your vet hasn't prescribed treatment, you can give to your horse Cushinaze https://www.cheval-energy.com/fr/produits-chevaux-sante-cheval/828-naf-cushinaze.html
Hoping to have answered your question,
Pauline from cheval-energy.com