Prascend for older horse without many symptoms?

[Libby2563]

Is it advisable to start an older horse (21) on Prascend just because, statistically speaking, he is likely to have Cushings? The horse in question doesn’t have any obvious symptoms except for anhidrosis (which he’s had since he was in his early teens and has been managed well by limiting riding to early mornings in the summer months) and some loss of topline (coinciding with reduced workload). Part of the rationale is to help heal a suspected soft tissue injury.

I’m not opposed to it necessarily (except the price tag!) but I do prefer medication to address a known need rather than be a shot in the dark. The vet who recommended this does not believe the tests are reliable enough to bother with. I’m asking my own vet to test ACTH and whatever else he recommends next week. I’m not sure he’s super well-versed in pituitary disorders though so I’m trying to do my own research too.

[findthedistance]

My vet has never recommended or prescribed Prascend without a positive ACTH test. (I deal in aged horses, so she and I work together on lots of horses with Cushing’s and other metabolic disorders.) The side effects are usually minimal, but they do exist. In general we try not to mess with the endocrine system if it seems to be working. Don’t fix what isn’t broken. Also, it’s not cheap!

I have seen Prascend/compounded pergolide used in an effort to stop laminitis in a clearly metabolic horse when a false negative is suspected and something needs to be done. That one wasn’t directly under my care, but I understand how that team came to that conclusion.

[JB]

It’s not a good idea as some “just in case”.

Now, that said, has this horse been tested? It’s about time now, through June, where you can do a TSH test to see what’s going on. One symptom of Cushing’s, or pre-Cushing’s, or PPID, or whatever early stage there is, can be injuries that are slow (all relative, I know!) to heal.

[Renn_aissance]

I would test the horse first. Pergolide has side effects, like any drug.

For what it’s worth, my horse’s symptoms were present for 10 years before he tested at an elevated ACTH (easy keeper, anhidrosis, tends to be slow-healing, profuse hair coat.) Vet and I felt a Cushings diagnosis was fairly inevitable but vet’s opinion was that pharmaceutical treatment was inadvisable until his bloodwork backed up our thinking.

[RedHorses]

Possibly not a concern, but if a horse’s PPID is managed successfully with Prascend and the horse goes off the drug for a while it can be difficult to get it back under control with Prascend. The drug company’s vet didn’t say why - it’s probably something that had been noticed and they hadn’t done any/enough research into that specific issue. I’d want the test done if I were in your situation.

[Libby2563]

Thanks, all! This horse’s ACTH was tested once before and came back normal but that was 5 years ago. Unfortunately my vet is out of the country this week so hopefully next week he can come out to test. I think the safest course is to keep him on the Prascend until then, yes? Or would you want to discontinue it at some point before the test to see what baseline levels are (though I’m sure they’d be affected by the 2 months on Prascend anyway)?

Should I ask the vet to test ACTH and TRH? Last time he just did ACTH. ETA: according to this article from May, TRH is not widely available: http://www.thehorse.com/articles/368…shings-disease. We may have to start with ACTH and go from there?

[JB]

It’s not the right time of year for the ACTH test. The only value it would have is if it’s SO high that it’s well outside any normal seasonal rise. The TSH/TRH is much more accurate right now. Once you have that baseline, then you can do the ACTH test in the Summers for keeping tabs on things.

[Libby2563]

@JB

It’s not the right time of year for the ACTH test. The only value it would have is if it’s SO high that it’s well outside any normal seasonal rise. The TSH/TRH is much more accurate right now. Once you have that baseline, then you can do the ACTH test in the Summers for keeping tabs on things.

I thought I had read that they have now come up with fall ranges for ACTH?

If ACTH isn’t appropriate this time of year and my vet can’t do TSH for some reason, what should I do about medication until the spring?

[quietann]

Wait, is the horse already on Prascend?

[Libby2563]

@quietann

Wait, is the horse already on Prascend?

Yes, he is. He was away on lease and the lessee’s vet started him on it. He’s now coming home because he’s lame and I’m wondering what to do. Sorry, I was a little vague in my OP.

[fordtraktor]

I did once but it was in the situation findthedistance described: “I have seen Prascend/compounded pergolide used in an effort to stop laminitis in a clearly metabolic horse when a false negative is suspected and something needs to be done. That one wasn’t directly under my care, but I understand how that team came to that conclusion.” It didn’t work but that was a “throw everything at the horse to try to save it” situation.

I wouldn’t give it just because. My guy really lost his appetite on it.

[betsyk]

My impression is that some vets are realizing that there are a lot of horses that have “sub clinical” Cushings that don’t appear with the typical symptoms. I can think of 2 or 3 in my circle of acquaintences that either tested positive but had no obvious symptoms other than chronic laminitis or soft tissue injuries that didn’t heal, or didn’t test positive, and had some mild symptoms that improved greatly with medication. (rotten sentence, sorry). Anyway, I suspect there are vets who are quick to try medication and others who are more conservative, and both may be right sometimes.

[Gainer]

@findthedistance

I have seen Prascend/compounded pergolide used in an effort to stop laminitis in a clearly metabolic horse when a false negative is suspected and something needs to be done. That one wasn’t directly under my care, but I understand how that team came to that conclusion.

This happened to me. I have an older WB that had chronic laminitis 2-3 times a year, for 4 years straight, despite my taking every precaution (restricted diet/muzzle, etc.) Tested every year for Cushings, but always negative.

This year, the horse got extremely shaggy, didn’t shed and developed anhidrosis. In spite of another negative Cushings test, we put him on Prascend. I wasn’t crazy about it, but was willing to try. This has been the first year in 5 years that we haven’t had a single laminitis episode.

[AA_Hunter]

I don’t know that I’d keep a horse on Prascend without a PPID diagnosis, but that’s something to discuss with your vet. My mare has been on it for over 10 years, since she was diagnosed at age 16, and her health has been wonderful–except for the excessive hair coat, she so far has had no other symptoms or complications (or drug side effects), and she was only recently retired. So I would definitely use it if clinically indicated.

[JB]

@Libby2563

I thought I had read that they have now come up with fall ranges for ACTH?

Right, that’s the “seasonal rise” that can be accounted for. The problem is, there’s a range, and if a horse is on the high side of that range, or just outside of it, is that because he’s heading into PPID territory, or is that just his seasonal normal? It’s really not until you get pretty significantly outside the high end of the “normal” range that you have a pretty reliable indication he’s PPID

If ACTH isn’t appropriate this time of year and my vet can’t do TSH for some reason, what should I do about medication until the spring?

Not a vet so I can’t begin to tell you. But I don’t know why a vet could not figure out how to get that test done.

[RedHorses]

If the horse has been on Prascend for a couple of months it will have some effect on his ACTH levels. If he’s in the normal range you won’t know if he’d be in the normal range without it.

I just had mine retested on Wednesday and his ACTH is right in the normal range. He’s getting one Prascend per day which is apparently still keeping his PPID under control.

But if I didn’t already know he has PPID we wouldn’t know either way from the results of the test.

[222orchids]

If your horse is already on it, do not stop it abruptly. Consult your vet for the best way to slowly decrease the dosage. Stopping abruptly can lead to founder

[Libby2563]

I looked up this thread for someone else so I thought I’d update!

I did end up weaning the horse off Prascend. In May his ACTH, insulin, T3, and T4 were all normal. Then in Sept his ACTH was elevated (even accounting for the seasonal rise) so he is going back on! Thankfully he doesn’t seem to have been suffering in the interim, other than getting fluffy a little earlier than the others.

I’ve since learned that the vet who put him on it without testing first likes to pick a “diagnosis du jour” and then decide all his patients have that. Apparently last year it was Cushings. But in my horse’s case, he might not have been wrong!

[newhorsemommy]

@Libby2563

I thought I had read that they have now come up with fall ranges for ACTH?

If ACTH isn’t appropriate this time of year and my vet can’t do TSH for some reason, what should I do about medication until the spring?

Most vets in my area now try to test this time of year. Liphook developed reference ranges for fall ACTH, and it looks like they’ve updated it since the last time I looked. https://liphookequinehospital.co.uk/wp-content/uploads/Seasonal-Changes-in-ACTH-Secretion2.pdf

[BWP]

@newhorsemommy

Most vets in my area now try to test this time of year. Liphook developed reference ranges for fall ACTH, and it looks like they’ve updated it since the last time I looked. https://liphookequinehospital.co.uk/wp-content/uploads/Seasonal-Changes-in-ACTH-Secretion2.pdf

My asymptotic 28yo wb had an ACTH level of 98 last week, so I will be starting him on Prascend this week. We’re now being advised that autumn is the best time to test as Cushings horses spike even more than non-cushingoids.