retesting acth and insulin

vicky monen


I wanted to check and see if retesting my guys ACTH and Insulin is sensible to do this month.  One of my vets indicated that it would be a waste of money due to the seasonal rise.  My guy's insulin was high in June and I have increased his prascend and was hoping that it may have come down some.  I also added in more exercise.  So, my question is,  would it be a waste of money to retest during the months of Sept or Oct?  He is Cushings and IR.  

Thanks so much. 
Vicky Monen and Samson

Aug 2015, Alpharetta Ga.


Hi, Vicky.
No, it's not a waste at all to check ACTH during the seasonal rise.  In fact, it's important to know that ACTH and insulin are well-controlled during the seasonal rise to avoid fall laminitis. I check every year! It's always an eye opener. If you want to minimize vet bills, it's probably better to test in the first week of July. That way you have time to adjust pergolide dose if ACTH is already elevated.

A good review on the requirements for testing is here:  For your part, it's helpful to review in detail the feeding instructions before the appointment to draw blood for Cornell. The bottom of the page includes this:
"To avoid a false-positive result, the horse should have hay available at all times the night before and day of the testing. If that's not possible (e.g., a ravenous horse that will inhale as much of anything you put out as quickly as possible), make sure the blood is drawn at least 4 hours after the first meal of the day, keeping some hay in front of the horse until the testing is done."

Cass, Sonoma Co., CA 2012
ECIR Group Moderator
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Eleanor Kellon, VMD

Most labs have seasonally adjusted reference ranges and there are multiple studies.
Eleanor in PA 
EC Owner 2001