PPID horses - keeping ACTH below 20 year round

Jenny Heishman

Hi all,

I'm educating myself on managing a PPID horse as my gelding, Rico, has recently been diagnosed as an early PPID case - he's an 11yo Rocky Mountain/Paso Fino cross.

I've read on a few moderator responses that the ECIR group aims to keep PPID horse's ACTH at or below 20 year round.
Why is that?  If healthy horses have a rise and fall of the ACTH with the seasons, why do we aim to level it out for PPID horses?
Just wanting to learn the reasons, I'm not questioning the advice itself.

Rico is on 1/2 tab Prascend for one week now.  Have the vet scheduled to do bloodwork in the end of November.

Jenny Heishman and Rico  
Bainbridge Island, WA   June 2018


I asked the same questions myself. The answers include the following:
1. Experience shows that PPID horses with tightly controlled ACTH have better long term outcomes.
2. What are the explanations? We don’t know for sure. Possibilities are that better consistent control inhibits or delays growth of the adenoma, slowing the progression of degeneration. This is based on human evidence of pituitary tumor growth being slowed by dopamine receptor agonists, including pergolide. Another is that comparing normals for normal horses isn’t valid compared to PPID horses whose dopaminergic neurons have been inactivated if not destroyed by uncontrolled PPID. 

This is a good time to review the physiology of PPID on ECIRHorse.org. I do it over and over. https://www.ecirhorse.org/physiology-ppid.php
Cass, Sonoma Co., CA 2012
ECIR Group Moderator
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