Thyro-l need for continued use/side effects

[Red2003]

My 16 yo Arab gelding had a mild founder and was diagnosed with Cushings and IR 5 months ago. He has been on pergolide (1mg) thyro-l (2 tsp( chasteberry (1 tblspn) and HEIRO (1tblspn) since he was diagnosed. His bloodwork is normal or close to normal now (we’ve run the panels 3x since he was diagnosed-- his acth came up a little in August, but the vet thought that might just be seasonal). In August his insulin was back w/in normal range, as was his thyroid. His overall weight also is good. He gets hay and equalizer.

his outward symptoms are still problematic. he grew a long coat in the middle of the summer and was sweating and panting, so I clipped him. His heat tolerance is better now, but he still sweats more and breathes more rapidly than he used to and more than my other horses. we are in Florida so the heat is a problem. and he is Still very PU/PD. in a stall with free access to a private paddock, he stands inside under the fan and soaks his stall–we add a bag of pelleted bedding every day.

I tried to put him back to work in the round pen and he is HYPED. He has always been a little hot, but now he is Mr. Hyde. He gets out of breath and sweaty fast (he hasn’t worked for a while) but he doesn’t slow down with it, he’s just more wired and reactive. And he is more reactive and nervous on his own–snorts and blows at anything new, chews at his stall and the fence if he’s isolated from my other horses and bites and kicks at my yearling if he’s turned out with him.

Is it the thyro-l making him nervous and irritable? I know over-supplementation can do that when humans are treated for hypothyroidism. Does he need it long term, since he is IR? if I cut it back, am I risking another founder from poor insulin metabolism?

[Lolliver]

I had an Arab gelding who was on Thyro-L for many years, and it never affected his personality. I would check with your vet before changing any dosage. As you are aware, the repercussions can be quite bad.

[fjordmom]

That has not been my experience with Thyro-L.

I have 2 horses on it, although at only 1 tsp dose. Both have been on it for several years now and it has never changed their personality or behavior. Both are very easy keepers and it has helped a bit with weigh control (along with other management). The more laid back/lethargic one has maybe become a bit more energetic over time, but in a good way. He is more bright eyed and whinnies a greeting regularly. Overall he just seems like he really feels good. Could just be that he is in proper weight and not carrying extra. He is neither IR nor Cushings.

My oldie who is IR and showing some early Cushings signs did have issues with in appropriate sweating before going on the Thyro-L. He is much improved after getting him on a low dose of the Thyro-L. He’s still in light work at 24 and looking like a much younger horse.

Both are also on Heiro and the oldster gets chasteberry as well. ACTH is not elevated and vet is not ready to put him on pergolide. I do think his coat is not as heavy since he has been on the chasteberry, so it is having an effect. He has always shed out properly both pre and post chasteberry.

Agree, consult with vet before making changes to Thyro-L (or the other meds too). Some humans get hallucinations when on pergolide. May want to ask about that connection.

[Zu_Zu]

NEVER had that experience with any of my horses or ponies Ӣ

Jingles & AO for your gelding’s continued recovery ~

• Always taper off Thyroid-L …and only AFTER vet rec.

[Red2003]

I forgot about the hallucinations side-effect of pergolide in humans. I’d joked with my trainer about it, too, when my gelding was first diagnosed: hallucinations for a horse prone to spook at stupid things anyway, oh what fun; let me know if he tells you he’s seeing things, etc. But I had not actually read about behavioral problems in horses, other than some depression (clearly NOT what is happening here). I do remember someone who showed Arabs saying 4-5 years ago that some halter trainers would put horses on Thyro-l to get a certain “look” in young halter horses (and doesn’t that sound atrocious) and that it was reported also to make them snort and blow more.

I will call the vet re his meds today.

[Palm_Beach]

A little thyro goes a long way, so there can be a difference if you increase or decrease the dose even a little bit. I would not make a change without consulting the vet.

With this horse, I’d do some desensitizing before putting him back in “work.” Chasing a horse around that is already a little hot without teaching him to relax and calm himself down is not a good place to start.

[JB]

What’s the specific reason he’s on Thyro-L?

It’s not (shouldn’t be) given JUST because a horse is IR. And not even just because he’s overweight. But if he’s morbidly obese, and/or overweight but diet changes aren’t making a change (or not fast enough), that’s a good reason to use it to get that weight off sooner rather than later.

Most hypothyroid issues caused by IR resolve once the horse is managed with diet. I would absolutely not keep a horse on this if his thyroid numbers are normal and his weight is at least not obese. It can definitely result in sending him into hyperthyroidism with resulting reactivity like he’s having.

But you do need to wean off it.

Equimed states “Dosages should be individualized and animals should be monitored daily for clinical signs of hyperthyroidism or hypersensitivity.”

[stb]

I had a horse that had a full blown panic attack on Thyro L. He was on a large dose at the time. Honestly, it scared the Hell out of me. I had him out at the time and was unable to get him back in a trailer to get him home. I swear that stuff made him see dead people.

[Red2003]

I have not yet talked to the vet, though I am waiting to hear from him. I expect, based on my earlier conversations with him and his pragmatic approach to endocrine management, he will say that I could try gradually reducing the thyro-l and see what happens.

Red is on the Thyro-l because his T-3 (or T-4, I can’t remember which right now) was low on his initial bloodwork and his insulin was WAY high. But he had been on bute when it was first taken and was only just off bute when it was rechecked the first time. I didn’t know that bute interfered with the test at the time of the initial and first recheck, and by the last one he had been off bute for a while.

he is not at all overweight now. His primary symptoms are a long, thick hair coat, a tendency to get skin crud (the thick coat and awful Florida heat don’t help with that), heat intolerance, and a significantly increased tension and reactivity. So, aside from the hair, those symptoms sound like symptoms a person gets with over-compensation with thyroxine. I am WELL aware of those issues in human metabolism, because I have dealt with a thyroid disease myself for 25 years. but I didn’t want to just assume that horses respond the same way as we do, and I didn’t know if this is a potential side effect in horses that you just have to live with in order to get the collateral benefit of better insulin management.

I have a somewhat negative view of my ability to manage all his special care long term. his feet are good. He is not in pain. But he is overheated (and it’s still 90 degrees here, at the end of October, no less). And his personality is SO off. He is grumpy. He pins his ears. He snorts and blows if I move a feed tub. and he is hateful to the yearling who is 1/3 his weight and seriously submissive (the yearling lowers his head and works his jaws/teeth in a “don’t kill me” pose every time Red pins his ears and bites).

He has always been a touch hot and occasionally spooky when he wasn’t worked regularly, but I used to say that he was at least polite about it. He had good ground manners, always. When I got him, he was a nationally competitive western pleasure horse. He wouldn’t crowd a handler, ever, and he understood that “whoa” means stop EVERYTHING. he would throw a buck (Or a few) when he hadn’t been worked in a while and a scary squirrel farted in his general direction. But he was willing, and he wanted SO much to please. But now he is on the edge all the time, and I am worried that he will hurt someone.

thank you, PalmBreach, for your input. Really, this isn’t a training or desensitizing thing. He is a smart boy and has been well trained by people a lot better than me, and I am at least experienced, even if I am not a professional. He was hot before and there were times I wished for a less reactive or emotional horse, But he is a different horse now. Is it the meds? The disease? A combination? And my real concern, is he going to be safe AND sound, or is this a losing battle?

i will talk to my vet about gradually tapering off the thyro-l. What really worried me was whether he needs the thyro-l long term. From your response, JB, I’d guess maybe not. So if my vet suggests or agrees with a gradual tapering off, it’s a reasonable way forward?

[Palm_Beach]

@Red2003

He has always been a touch hot and occasionally spooky when he wasn’t worked regularly, but I used to say that he was at least polite about it. He had good ground manners, always. When I got him, he was a nationally competitive western pleasure horse. He wouldn’t crowd a handler, ever, and he understood that “whoa” means stop EVERYTHING. he would throw a buck (Or a few) when he hadn’t been worked in a while and a scary squirrel farted in his general direction. But he was willing, and he wanted SO much to please. But now he is on the edge all the time, and I am worried that he will hurt someone.

thank you, PalmBreach, for your input. Really, this isn’t a training or desensitizing thing. He is a smart boy and has been well trained by people a lot better than me, and I am at least experienced, even if I am not a professional. He was hot before and there were times I wished for a less reactive or emotional horse, But he is a different horse now. Is it the meds? The disease? A combination? And my real concern, is he going to be safe AND sound, or is this a losing battle?

So you have desensitized him and he reacts appropriately? Or you think it’s not necessary because the good horsemen before you were so good that the training they did lasts forever and he never regresses? I find that they usually regress to some extent when not worked regularly, but maybe it’s just my ineptitude.

[Red2003]

PalmBeach,
I’m saying that this is not A reaction to isolated, discrete stimuli, or even categories of them. He doesn’t act like a horse that needs to be sacked out in order to be reminded that ropes aren’t snakes, for example. He is tense and reactive generally, on his own in his stall and private paddock, in the dry lot paddock with other horses, coming in to the barn, going out of the barn, and with me.

[Bluey]

@Red2003

PalmBeach,
I’m saying that this is not A reaction to isolated, discrete stimuli, or even categories of them. He doesn’t act like a horse that needs to be sacked out in order to be reminded that ropes aren’t snakes, for example. He is tense and reactive generally, on his own in his stall and private paddock, in the dry lot paddock with other horses, coming in to the barn, going out of the barn, and with me.

Our Cushing’s gelding has been on T-L for some years now, along with Prascend and has not changed.

On testing he was the lowest our vet had ever tested, gave him a shot right there and put him on five spoonfuls for some days, then tapering off to the two he has been on for some years now.

Not sure your horse may have changed just because of that medication.
There may be more going on, check eyesight, check other, neurological exam, etc.

I would rule other out before assuming it was the T-L supplement, but never say never, maybe it is.

[Laurierace]

I know you don’t want to add another med to the list but what you are describing sounds like it could be ulcer related to me. Something to consider especially since you say he was on bute.

[JB]

@Red2003

i will talk to my vet about gradually tapering off the thyro-l. What really worried me was whether he needs the thyro-l long term. From your response, JB, I’d guess maybe not. So if my vet suggests or agrees with a gradual tapering off, it’s a reasonable way forward?

I would hope at this point your vet would recommend weaning off. It’s pretty uncommon for a horse to need to stay on a low dose. Most vets, IME, won’t even prescribe it unless there’s a serious weight issue, no matter what the thyroid test says, because getting control of the IR issues through dietary management almost always starts resolving the thyroid issues. Sometimes they need help though.

As for all his other issues, if it were me, I’d wait to see how things shake out after being off the T-L for long enough (and I honestly have no idea how long it takes to fully clear the system) before deciding maybe he’s having other issues

Not everything is a training or management issue. When you have a horse on new meds, and he’s acting feral all of a sudden, it’s not a training problem.

But Laurie’s suggestion of ulcers is also a good one. And maybe it’s a combination of ulcers and a reaction to the T-L. How long had he been on bute, what dose, and how long has he been off it?

[bingbingbing]

My vet had me try my super easy keeping (fat) gelding on Thyro-L. He said if he gets wild, he doesn’t need it. Within a week my very quiet horse was rearing in the stall and totally nuts. I weaned him off of it and he went back to being his quiet self.

[Red2003]

He has been off bute for months, so I don’t think he’s necessarily an ulcer risk. He was on bute for only the first 3-4 weeks after the founder. But he had been on it for a week before the first blood test, because we thought his mild lameness was from a knee bump he collected in the trailer, and he had been off bute for only a week or so when we tested him again to see how he was responding to the pergolide. At that time, The lab thought that having been off bute for only a week was not long enough to give us a reliable T-4 result.

When i talked with my vet this am, his first question was whether Red was maintaining his weight well. He is—the weight tape reads between 932 and 966 consistently, and he’s 16h. My vet’s agrees that hyper reactivity or irritability are not common reactions for horses on Thyro-l, but he thinks it can happen and suggested cutting the dose in half, since we aren’t having weight problems. I will do that gradually and see what happens.

Thyroxine uptake in humans can be blocked significantly if it is taken in conjunction with iron, like a simple multivitamin (not to mention prenatal vitamins) or even food that is iron rich. Many GPs don’t realize that, so it’s not among the common warnings, but it’s the reason people are supposed to take levothyroxine on an empty stomach and not eat for 1/2 an hour after.

I know we can’t assume the same is true for horses (or even for Thyro-l vs. levothyroxine) and my vet does not know whether it is a factor. But When I first put Red on the Thyro-l, I didn’t really give any thought to the iron-binding problem in people. It only dawned on me one foggy-headed morning when I was staring at my own medicine cabinet, so around August I started giving Red his vitamins only in the evening instead of splitting them between the 2 feedings. Now I wonder whether he’s absorbing—and feeling—the thyro-l he’s getting more than he did a couple of months ago.

[EmilyM]

when i had to put one on thyro-l, my vets started me on 1 teaspoon and just mentioned that if they get squirrely or reactive, it often means they need a lower dose. for whatever that is worth. good luck

[Laurierace]

My horse got ulcers from one dose of bute

[Simkie]

Have you joined the Yahoo Cushing’s list? It’s an excellent resource and there’s info there about thyro-l use–generally that it’s not needed. There are a lot of vets out there that aren’t staying current on the research. Poke around there and see what you think, but I’d taper that stuff and get him off of it as quickly as is prudent.

Then consider if you need to treat for ulcers. I also have a horse that will get them with a single dose of bute. On it for 3-4 weeks is all but a guaranteed case.

[Red2003]

@Laurierace

My horse got ulcers from one dose of bute

WOW. And both vets in the practice I’m using here in Ocala and the vet I used for 20 years in the town I just moved from insisted that it is completely safe as long as the horse is getting adequate hay.

I will keep ulcers in mind. If Mr. Hyde doesn’t improve I will talk with the vet about checking him for them. I will likely ask him to do bloodwork again next month when everybody gets their shots and Coggins tests.

I couldn’t figure out how to get to the Yahoo list thing. My internet skills are pretty remedial.i have browsed around on the ECIR page (where there was zero mention of thyro-l.

Thank you for all the replies and advice. I think both of the vets in the practice I’m now using are excellent, but I don’t know if they see many horses with Cushings and IR.