Starting PPID treatment in autumn?


I've been following these groups for many years but seldom post. Hopefully I have posting etiquette correct.

I have an older Morgan gelding (21) who I suspect of Cushings. I am going to work with my vet to get a blood test(s) done but in meanwhile am doing some reading and on the ECIR Seasonal Rise page, I noticed that it says horses may not respond to treatment if it is started in the fall. My questions are: should I try testing and treatment now or would it be a waste of money? If not now then should I wait on the test, and when is autumn considered over for this purpose? 

I've not started a case history on him (Primo) yet, but will list reasons for suspicion: age, breed, large increase in drinking and urination in autumn (probably at least 5 years), loss of topline (past 2 years), and increasingly abscess-prone as well as irritated by biting gnats to the point of rubbing raw spots. He has not foundered and has not got the fatty deposits or cresty neck typical of IR-prone horses so I am not as concerned about that. His mother lived to age 34 and likely had Cushings as well given her yak-like winter coat that lasted well into summer.

My main concern is that this past year he seems to always be recovering from or on the way to hoof abscesses and it is of course painful to him and not fun for me. My vets and farrier both live miles away so I cannot necessarily just run to them when something comes up.

Martha in New Mexico
Primo, Lucy, Chinle

Sherry Morse

Hi Martha,

The sooner you get him tested and on medication if necessary the better even though you are "chasing the rise" by waiting this late in the year.  As he's had symptoms for years I would expect him to need more than 1mg to control his ACTH whenever you decide to start him on medication.


Hi Martha,
If he were mine, I would test him soon, which will give you an idea of how high his ACTH and insulin might get at its highest.  The peak is the third week in September so the sooner you do that the more information available but no need for panic to get it done.  I would not choose to do a TRH stim test because there is no standardized interpretation of those results during the rise.  I would test insulin and glucose as well.
When I got those results back, I’d decide how important it was to start pergolide right away and what my dosing plan might be.  I’d want to locate some APF, source my Prascend and then start to titrate up the Prascend.  By then, I'd be so far on the back side of the ‘rise’ that I would not expect to see much loss in Prascend effectiveness.  So the goal at this point would be getting him to an adequate dose to control his PPID before late June comes along and the rise starts again.  The peak of the fall rise is the autumnal equinox about Sept 21.  It begins and ends 3 months on either side of the peak.  It’s aligned with many other fall transitions.
Martha in Vermont
ECIR Group Primary Response
July 2012 
Logo (dec. 7/20/19), Tobit(EC) and Pumpkin, Handy and Silver (EC/IR)

Martha and Logo