Speedy Got a 24!

On Friday afternoon, I got a very surprising and happy phone call. Dr. Tolley called to share that Speedy's ACTH number came back at ... wait for it ... a 24! I think Dr. Tolley was even more surprised than I was!

He's normal!

A horse's normal ACTH, Adrenocorticotropic hormone, is between 9 and 35. High levels of ACTH cause an over production of cortisol from the adrenal glands which affects all sorts of systems. When we first tested Speedy in January of 2019, his ACTH level was 56. That's when my vet first diagnosed him with PPID, also known as Cushing's Disease. When we tested Speedy again this February, he was at a 134, even on a 1mg dose of Prascend. That was not a good sign.

We doubled his dose to 2 mg of Prascend and then backed that down to 1.5 mg with the plan to retest him at the end of ninety days. I wrote about that last week, which brings us to today. My vet says that Speedy is now what he would consider "under control," and his dosage, 1.5 mg, is perfect. But.

I just couldn't leave it at that because PPID is not a stagnant disease. Horses' ACTH levels fluctuate all year long, particularly in late summer/early fall. So I asked more questions. What do we do when ... ? What do we do if ... ? When should we check ... ? 

Dr. Tolley's answers were pretty simple. ALL horse will show a rise in their ACTH levels if we check them in the fall, which is what I wanted to do. The problem is determining whether Speedy's ACTH levels have risen because the dosage isn't working or because they've risen normally. Essentially, Dr. Tolley is looking at it like this: Speedy ACTH level is now at what a non-PPID horse's level should look like. If we test him again in September, his numbers WILL rise like any non-PPID horse's would which is why that can't guide our decision to change his Prascend dosage.

Our plan is this: if Speedy has one late summer/fall abscess, we start watching him closely. If he has a second one, we re-test his ACTH levels and go from there. If he has no abscesses, we still recheck his bloodwork in late winter to get a new baseline for the next year. We'll adjust his medication based on that number.

With his numbers back in the normal range, I should be really happy, and I am, but I also want to keep ahead of things so that we can avoid those pesky abscesses. Future worries aside, the number 24 is a great thing to see.