TRH test marked elevation in Fall


mroseu@...
 
Edited

Hi there. I have a 16yr QH gelding that has always had a cresty neck and fat pockets behind his shoulders. Even in heavy work and when fit. He has been on pasture and a ration balancer. He was normal on baseline ACTH and insulin levels in March 2020. He looked a little more crestu and has been acting footsore some days that comes and goes and not improving with rest, adequan and joint injections. I was going to retest him this fall but this was hastened by him. He has had some SI issues and had PRP for this and recheck with his vet this Tues. He was looking really good the past weeks leading up to it although I did occasionally see him toe pointing on the  RF and once was standing parked out while tied but moved normally when lounged. 
The barn moved him the morning of the recheck to a new pasture. He was on it for about an hour. When I came to get him he was tripping some and off on both forefeet solid 3/5 at trot on a tight circle but looked okay straight and walking normally. By the time we trailered to the vet about an hour away, he looked great. They pulled Cushings test while there to be safe and called me and said, start Prascend today and get him off the grass immediately.
This clinic said start at 1tab a day but his usual vet said do 1/2 tab for two weeks before increasing to avoid side effects. 
His values are ACTH base 46, after stim 1118
Insulin 48 uU/ml Glucose 89 mg/dl
He looks fine today, no lameness, normal digital pulses. I am following their recommendation but from what I found on this group I am unclear about these results. With the stim that high is he Cushings despite the baseline? The reference lab said over 500 in the fall was diagnostic. 
Should I start him at a full tab or do the 1/2 tab recommendation? 
We are doing the diet changes recommended for insulin resistance. He had hoof rads two months ago but my vet is coming out to reshoot them this coming Tues to make sure nothing is changing and recheck to make sure this isn't navicular or something. Thanks for any advice!
--
Melody 
Brandywine, MD
Joined Sept 2022


Sherry Morse
 





mroseu@...
 

Thanks for the response. He was only tested the one other time in April 2020 and his baseline ACTH was 10.7 and baseline insulin 12.7. 
If we do not start pergolide now, would it contribute to making our suspected IR harder to control? I wanted him retested this year anyways because his summer coat was a little thicker than normal and on hot days I would find him sweating on his neck and chest when he was just out in the field. He has also had insect allergies and given himself an eye ulcer once with rubbing his face so badly. We had been putting a mask on him which helped but reading here it looks like those could be early signs of endocrine issues for him. 
Would it be safer to just it him on pergolide for now and then wean off and retest later? How exactly do we go about doing that?
The internist at the clinic acknowledged they don't like to interpret tests post trailer but that the stim result was so remarkably high combined with his clinic sign they felt it likely there was some truth to it and you wouldn't be able to get that much of a rise just from trailering etc

--
Melody 
Brandywine, MD
Joined Sept 2022


Kirsten Rasmussen
 

Hi Melody, 

You can start him on pergolide to be on the safe side, especially if you have seen physical signs that support PPID.  Despite everything, that is still a very high TRH result.  Howecer, it's so late into the seasonal rise that a dose of 1mg is unlikely to take much effect until after the rise ends, but it may help.  That's why we recommend getting the effective dose in place in late July, so for future reference next year...  In the meantime, insulin is the biggest concern.  With an insulin of ~50 I would start soaking the hay, which can help offset the effect of high ACTH on insulin through the rise.

After December, you can stop the pergolide, wait for 3 weeks so his ACTH can return to his normal, then redo the TRH Stim at home.

--
Kirsten and Shaku (IR + PPID) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
 
Shaku's Case History
Shaku's Photo Album


Kirsten Rasmussen
 

I should add, no pasture right now when insulin is high, and you may need to do a diet overhaul to help lower that insulin.  See the Diet section of Sherry's welcome letter.

My horse was diagnosed early PPID in November 2020, so he went through that seasonal rise unmedicated.  I had to soak his hay through that seasonal rise to prevent laminitis, which kept his insulin nice and low, and the 2 times I stopped soaking (Aug 2020 and Nov 2020) he had a flareup.  What he really needed was pergolide, but we didn't start that until March 2021.  Getting pergolide started allowed me to stop having to soak that hay the next seasonal rise (he was eating the same hay both years, so that variable didn't change).

--
Kirsten and Shaku (IR + PPID) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
 
Shaku's Case History
Shaku's Photo Album


Sherry Morse
 

Hi Melody,

Well this is additional information which is one of the reasons we like to have a case history so we can see the whole picture.  Knowing his current diet would also be helpful.  As his insulin wasn't in the danger zone for laminitis even with trailering I would still be hesitant to start on medication without a retest once we are fully out of the seasonal rise (January) and I would concentrate on getting his diet correct and his trim in order between now and then.

If you do decide to start on medication you would titrate up over 4 days for each increase and then to wean off you would stop the medication and then wait 3 weeks to retest in January.  That test should be done at home following the guidelines in your welcome message.