I would wait until you repeat and ACTH stim test and potassium level before adjusting the dosage. If he is maintaining well now with no clinical signs then that means that the medication is working. Prematurely decreasing the dose could lead to undermedication and a return of symptoms. Your vet should be having him tested initially every 3 weeks which changes to every 3-6 months therafter. I am so please to see that more vets are using trilostane now in the treatment of Cushing's disease as this drug has the least amount of side effects then past drugs used.
Please let me know what you think about this plan.
Yes, I would consider rechecking the bloodwork at the current dosage you are using. If it is within normal limits then no change will be needed. Yes, he will need to take the medication as he normally does so if it would be his regular day off then it isn't necessary to give the medication. The blood can be drawn at any time as long as it is 4-6 hours after giving the medication. Stay on the same schedule don't give any unusual doses the day of the test. I sure hope this makes sense to you, please let me know if there is any confusion.
Are you from the US or England?
You should be able to get this product at doses of 15mg, 30mg, 60mg, and 120mg. You will most likely need to go through a compounding pharmacy to do so but it can be done. Since they are capsules you won't be able to decrease this yourself although I have known clients who have split them using a special scale to do so I don't recommend that.
Lets get the test done first. See where they levels are and then adjust from there if necessary.
He would show symptoms of addison's disease the reverse of Cushing's which is caused by too low of a cortisol level. These symptoms include decreased appetite, lethargy, weakness, and vomiting.