Vet called...Just got the results back from her 11 day ACTH test following Millie's start on Trilostane. For reference I am posting the ACTH results pre-treatment as well:

Pre-Treatment:
Cortisol Sample 1: 2.1 ug/dL
Cortisol Sample 2: 8.5 ug/dL

11 Day ACTH:
Cortisol Sample 1: 0.8 ug/dL
Cortisol Sample 2: 5.0 ug/dL

Do you have the lab's reference range for the pre ACTH test?
I am no expert but something is off somehow. Is that the original ACTH test to diagnosis is inclusive as it shows normal cortisol?

Coritsol sample one after 11 days is pretty low. Dechra prefers it not go below 1.45ug/dl.
Cortisol sample 2 is fine.

I am sure one of the administrators will stop by with thoughts.