Another cushings thread... Maybe IR? Pergolide not working? WTF do I do?

full disclosure My vets are involved. While they’re doing some research on what to do, I figured I’d do my research too. Which has me in a tizzy.

22 year old QH mare with PPID that had been “eh, could be better, but could be a lot worse”. Just got test results back and my vet says he’s never seen such high ACTH results… :confounded: She’s been on 3 mg compounded pergolide capsules since last summer, which was an increase. She has been testing high, but my vet said today’s protocol is to treat symptoms even if ACTH results don’t come back down to normal range. The mare has not foundered. Symptoms are hypertrichosis, topline muscle wasting, and some fat deposits. Increasing to 3 mg last summer had a positive impact on her hair coat and topline. I just had her tested this week, along with testing for IR. Results:

Baseline ACTH: 124 (normal range < 35)
ACTH TRH+10: 777 (normal range < 110)

Baseline insulin: 37.7 (normal range < 20)
Insulin OST+60: 57.9 (normal range < 45)

Baseline glucose: 82 (normal range 71-122)
Glucose OST+60: 94 (normal range < 125)

Can someone help me break down the insulin and glucose test results? I’m deployed at the moment, so my mom has hauled the mare for testing and had the conversation with my vet. He said “IR is good”… I don’t know what that means when her insulin results are higher than normal. But glucose plays a role in this? I should know this, I have a degree in animal science. But I can’t make my brain work through this right now…

Vet said we may need to go as high as 5 mg of pergolide. Also said he is looking in to adding cyproheptadine. All the research I have found suggest that cyproheptadine is not useful in controlling ACTH levels. Has anyone had any luck with cyproheptadine in ADDITION to pergolide?

Her last test had a lower baseline number, but higher +10 number. Granted it was in the fall so I guess seasonal rise could be to blame.

What on earth do I do? Treat symptoms? Treat ACTH level? Pergolide is eyewateringly expensive, but I’ll do it if we have to. But what happens when 5 mg fails to control it? What if it doesn’t control it at all right off the bat? Do I add another drug? Oh by the way, she’s on gabapentin for a trashed stifle.

The horse has a great quality of life; aside from not being allowed to graze grass. That’s a whole other question… Lives in a quiet “cripples only” paddock and aside from being slow moving due to the stifle, she is a pretty happy horse with her joint injections, Pro-Stride, pulse sessions, dental, an understanding and patient farrier, etc. So I don’t think we’re looking at an end of life type thing, but I don’t know what to do to get this frustrating disease under control.

And if anyone would care to chime in regarding her insulin results, is it simply not safe to let her graze at all? I would love to let her have some grass, but can’t interpret her insulin results.

Someone send help…

Compounded pergolide did not control ACTH levels in either of my Cushing’s horses. I currently have one on 1 mg Prascend and the other on 2 mg Prascend in order to control the PPID. My personal experience with compounded drugs is that some work better for some horses than others, so the effects can be anything from nothing to everything desired. Some compounded drugs, like Pentosan, seem to do the job well for most, but others, like pergolide, don’t. Perhaps it’s the difference between liquid (injectable) and powder (capsules). My suspicion is that compounded powdered drugs in capsules don’t ensure inclusion of specific amounts of the drug.


Switch over to Prascend and what is horses diet?

Is the hay low sugar? Any grain that might not be safe given?

I’m a huge component of adding cinnamon to help regulate insulin levels but diet has to be stellar.

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Take a look at the ECIR website. She has excellent research regarding all things metabolic.

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Your problem may be the compounded drug. Pergolide has a very unstable shelf life and my vet has said that compounded pergolide may not test as having what it is supposed to have. I would try Prascend and see if that helps. But also sometimes nothing controls the Cushings very well after a while.


The ECIR site has never lent itself as much help for things I’m looking for. Seems like their main focus is laminitis. Not every cushingoid has laminitis. Maybe there’s more info there to be had, but I haven’t found it…


Thank you for your service, first of all. I believe Ohio Stare recently did a study comparing Metabarol, aspirin and Metformin on insulin levels. I’ve been looking for it, but have not found it, so it may not be published yet. It was done w a grant from the Grayson Foundation. Anecdotally, my vet said he doesn’t worry about laminitis until insulin hits 200. I have 2 horses on Metabarol in my barn. (Their diet is well managed). He also doesn’t worry about ACTH becoming completely normal. Mine is on 21/2 mg of Prascend. My personal goal is to get him to normal. I know I didn’t answer your questions but hope I’ve given you a bit of peace of mind. Oh- another vet did tell me we could add cyproheptidine if need be.

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I wondered about this. I went with compound as an attempt at keeping cost a bit lower since we knew she would be needing increased dosage. I went with capsules because I understand them to be relatively stable (in comparison to powder or liquid). It makes sense that it could work for some horses, but not for all. I wish there was a better way to get that answer besides trial and error…

As a side bar, my vet won’t use compounded drugs unless there is nothing else available. Perhaps the switch to Prascend would solve your problem.


I think I might need to switch over…

She is on free choice alfalfa that is very low in sugar. I have misplaced the test results so I don’t remember the sugar content, but I do remember the starch is at .2%. Also 1 1/3 pound of Enrich ration balancer with a pound or so of Triple Crown Senior for palatability split in to two feedings.

I’m thinking that’s what I may need to do. My vet was willing to try it with knowing it may not work quite as well. But with her ACTH results as high as they are, wouldn’t you think that means it’s not working at all??

We did the compound knowing that we may need to switch back to Prascend. But sheesh trying to decide if it’s the pergolide or she’s just not reacting anymore is a pain in the rear end…

Buckeye Gro N Win is 1% lower in NSC and our horses LOVE it. In fact, I use it as a treat for my 2 1/2 Prascend pills to go “ down the hatch”.

Interesting. I don’t have access to Buckeye but I do know I can get it on Chewy if I need. I had decided against Buckeye because of the added iron, but I do realize that my phobia of added iron is unwarranted. Just gotta convince myself to let it go.

I forgot to add that she does get 2 starbrite peppermints twice a day ground and mixed to mask the taste of her gabapentin. But in the grand scheme of things, it’s a minimal amount of sugar. Especially considering her insulin levels aren’t ungodly high.

Oh…we just had an older mare tested for PPID. She’s exhibited clinical signs forever (primarily in her coat) but ACTH blood work didn’t support it, so her owner did nothing. She just was tested again…pre TSH levels were 22; post TSH was 1200.

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Yikes! I thought I had remembered some horses testing in the 4 figures. I may need to send an email to the clinic and cc a few vets on it. The “endocrinology guru” that we usually see was not the one testing her this time. So I may email her as she may be a bit more up on current protocol than the “mare management guru” that saw her this week.

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Capsules are powder, hence the instability. In the long run Prascend will probably save you money over compounded pergolide, just because the dosage is so much easier to control. There are generic drugs and compounded drugs which work well, but many compounded options don’t. I’ve used compounded omeprazole, which did pretty much nothing at all compared to Gastrogard.


I think I remember researching and finding that since the powder is contained in a sealed(?) capsule, that it was more stable than powder in a jar. Anyways, technicalities. Regardless, I agree that we need to try prascend again. I’m typing out an email to my vets now.

Also, I notice the same with compounded omeprazole. I wish there was a more cost-effective option than Gastroguard. Or really any of the brandname drugs that we rely on.

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When my pony first got diagnosed he received an injection of Cabergoline (sp) and then was put on a half pill of Prascend three days later.

Might be worth asking about the shot (I’m assuming it’s still around) to get the numbers down.


I definitely asked about it in the email I just sent. I’m not familiar with how it works. So perhaps it can be used to get the baseline down, and prascend to maintain?

That was years ago. Vet didn’t have Prascend on the truck and had to have it shipped. Said shot would get numbers regulated and then should be good with half a pill. Then we retested to check dosage after 3-4 months.

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