Re: New Study
Eleanor Kellon, VMD
Since that post I have had a chance to review the entire article.
Time of day of sampling makes no difference in baseline ACTH or ACTH after TRH stimulation.
Season (fall) can result in false positive ACTH stimulation by TRH.
Fed versus fasting (fasted 12 hours) had a higher baseline ACTH result but both were actually within normal limits.
Fed versus fasted ACTH response to TRH can produce an abnormally high ACTH response in fed horses but this is in horses fasted for 12 hours before they are fed (meal of 3 kg alfalfa).
This data is from horses 8 to 10 years old so may not apply to older horses.
Bottom line IMO is that testing for both ACTH and IR should be done with horses having constant access to low sugar/starch hay from night before and day of testing.
Eleanor in PA