Sorry I was gone yesterday afternoon and didn't see your reply until this morning. I want to clarify that Lulu may be doing just fine on this dose of trilostane, and her rear-leg weakness may only be from arthritis that has been "unmasked" by her decrease in cortisol. But her 30-day post-ACTH result is low enough that you really do not want it to drop any further. Individual dogs metabolize the drug at different rates, so what may be a "low" dose for one dog may turn out to be a "high" dose for a dog of the very same weight. That is why the monitoring ACTH tests are so important in terms of making dosing adjustments. The initial dose is indeed calculated on the basis of weight (the makers of brandname Vetoryl recommend a formula of 1 mg. per pound). But that is just a starting point, and the dog's appearance, behavior and subsequent blood testing all guide the subsequent dosing.

I think it's great that you are seeing so many improvements in Lulu. And as I say, this dose and ACTH level may prove to be just fine for her. But I wanted you to be aware that you do not want her cortisol level to drop any further. If it does, you will need to decrease her dose. Here's a link to the U.S. Product Insert for brandname Vetoryl. It contains a lot of helpful info re: monitoring and potential side effects to watch out for:

http://www.dechra-us.com/files/dechr...ts/Vetoryl.pdf

Marianne