HYPERthyroidism in Horses

[appychik]

... is extremely rare, if nonexistent in horses. I know that. So, why does Gus keep testing well above the norm?

5/07 - 4.4 (range 1.1 - 2.8)
6/07 - 3 (range 1.0 - 2.8)
4/08 - 3.1 (same range as above)
1/09 (yesterday) - 3.9 (I believe the same range)

FWIW, we've always used the same lab to process the T4 panels. Same system, so shouldn't have any lab discrepancies... He's NEVER been on any thyroid supplementation in the 9 years I've had him, and I'm 99% positive he was on nothing prior to me purchasing him.

WTF? We originally suspected something in the spring of 2007 because Gus had dramatically dropped a lot of weight, a lot. Very unusual for him, as he's always been an extremely easy keeper. After getting a few pounds on him we retested, hence the first two tests relatively close together.

Anyways, rDVM is gonna ask another vet (again) if she has any ideas... we're all really stumped. This has been the first winter in two years (knock on wood) that Gus has been maintaining weight well. However, it is also the first winter where he's hardly been in any work, whatsoever!

So, any suggestions? Ideas? Questions I could ask the vet? We're all really stumped.

ETA: Could use some jingles that the stifle injections worked this time too! I'm really hoping I'll have a 50% sounder horse today when I get to the barn...

[Dalemma]

Not sure when you got stifle injections but it takes 3 to 4 weeks to notice maximum results.

Dalemma

[BornToRide]

I do not believe it is that rare, I believe the tests are not sensitive enough to pick up more potential problem cases.

Even in humans thyroid dysfunction is notoriously misdiagnosed, usually though low thyroid function. Did you hear about Oprah's 4 doctors missing the condition and treating her for symptoms with wrong medications??

I do believe that some hard keeper type horses may actually suffer from high thyroid function! You may be onto something!:yes:

[appychik]

Stifles were done yesterday also. I've always noticed a HUGE difference within a week. :) Hoping for the same results this time.

[appychik]

I do believe that some hard keeper type horses may actually suffer from high thyroid function! You may be onto something!:yes:

Thanks. I think there is a correlation, but unfortunately no studies have been done and it seems like nothing is written out there. Just really weird. Thankfully he has no other "issues" persay with his overactive thyroid. He's definitely not hyperactive, like you'd think... or should I say, acting like he has energy. He's still sluggish and could care less about everything but food. That's normal for him

Just wondering if anyone else has every had a horse with above normal T4 values, or if Gus is just special :winkgrin:.

ETA: I think I had heard something about Oprah... but don't recall exactly what it was. Love her show though when I'm home to watch it.

[BornToRide]

Yes, it can result in sluggishness because the body never gets a chance to rest well and gets stressed more.

[appychik]

Yes, it can result in sluggishness because the body never gets a chance to rest well and gets stressed more.

Aww, interesting. Didn't think about the fact that his body wouldn't have a chance to fully recover. Makes sense though. Still...

So, hyperthyroid cats get Methimazole to help with overactive thyroid glands... wonder if there have been any studies with horses and that particular drug?

[Ghazzu]

From a recent discussion amongst equine practitioners that pretty much sums it up:


"Reference range data for T4 are just an expected range. There's no
data to support that levels below that range are associated with
clinical disease in horses."

I would say the same is true regarding elevated levels, especially those that fall close to the expected range.

[deltawave]

Is this a free T4 level? If the animal has more TBG than usual, (the protein that carries the active thyroid hormones around) then the amount of available ("active") T4 may be lower, and the body will mistakenly crank up the production of more T4. Albumin can also carry T4 around, and excess albumin may have the same effect. Pregnancy and steroid use can increase TBG levels. What are the animal's TSH, free T4, and T3 levels?

[appychik]

Is this a free T4 level? If the animal has more TBG than usual, (the protein that carries the active thyroid hormones around) then the amount of available ("active") T4 may be lower, and the body will mistakenly crank up the production of more T4. Albumin can also carry T4 around, and excess albumin may have the same effect. Pregnancy and steroid use can increase TBG levels. What are the animal's TSH, free T4, and T3 levels?

:lol: The only thing I got out of that was pregnancy and steriod use can increase TBG levels... and ugh, Gus can't be pregnant cause he's a gelding... and he's never been on steriods. :yes:

Anyways, in all seriousness, I pulled his lab results. Looks like a T4 was all that was done, not a T4 panel (which would show the free T4, T3, etc). I always get T4 panels on myself and dog done (dog is hypothyroid... my doctor just likes it done routinely in patients she sees). So, not sure why they just tested for the T4, but whatever.

Here's the results of all four tests, and all the information I was provided:

Thyroid Panel__Ref. Range__ 5/9/2007__6/21/2007__4/4/2008__1/8/2009
T4_____________1.0-2.8 ug/dL___4.4________3*__________3.1________3.9
Chol____________50-140 mg/dL___86__________89_________90
QC____________________________OK__________OK______ ___OK
Hem____________________________0____________0_____ ____0
Lip____________________________1+___________1+____ _____1+
ICT____________________________0 ____________0___________0

Still haven't gotten the full results on the rest of the labwork. I typically get that emailed to me when they send my bill. So within the next week or so I should have the rest of the information.

So, should actually be having a full thyroid panel done? One like what I (and my dog) typically get? Sheesh, and all this time I thought that's what I was having done...

[Katy Watts]

So, should actually be having a full thyroid panel done?

Yes, if you want to get the full story. Unless you specify, you generally get a number that means T3 and T4 added together. I have used Cornell for T3, T4 and free T3. While you're at it, you might consider blood selenium levels, which Cornell can also do. Se deficiency can slow conversion of storage form T4, to active form T3. So more gets made, only it doesn't work properly. full text article:
http://www.ajcn.org/cgi/reprint/57/2/236S

Katy

[cloudyandcallie]

32 year old quarterhorse boarder where we used to board had hyperthyroidism and cushings. He was tested and treated by our vet, and I think he is still alive. They put him on the standard treatment for cushings but because of his weight loss he was taken off of the drug.

I hope Gus gets treatment that will help him feel better. You have taken such good care of him.

[appychik]

Yes, if you want to get the full story. Unless you specify, you generally get a number that means T3 and T4 added together. I have used Cornell for T3, T4 and free T3. While you're at it, you might consider blood selenium levels, which Cornell can also do. Se deficiency can slow conversion of storage form T4, to active form T3. So more gets made, only it doesn't work properly. full text article:
http://www.ajcn.org/cgi/reprint/57/2/236S

Katy


Well, I'll see if I can get the vet to recheck the thyroid when she's out in the next week or two when she does the ACTH Stim Test...

However, we did test the selenium back in June '08. He was 0.17 ug/mL (ref. range is 0.14 to 0.25 ug/mL). He's on no additional selenium supplementation, with the exception of his multivitamin, which provides 0.9 mg. Not sure what the hay provides... his grain provides roughtly 0.34 mgs per meal (so double that per day). FWIW.

At the same time we tested the selenium, we also tested vitamin E. That was well with the normal range... right smack dab in the middle, actually.

So, would you supplement selenium? Vet said since he was within the normal ranges not to worry... but ???

[appychik]

32 year old quarterhorse boarder where we used to board had hyperthyroidism and cushings. He was tested and treated by our vet, and I think he is still alive. They put him on the standard treatment for cushings but because of his weight loss he was taken off of the drug.

I hope Gus gets treatment that will help him feel better. You have taken such good care of him.

Aww, thanks Cloudy. The good thing is that just 24 hours after his stifle injections, I think I noticed some improvement. BO/Trainer said he's still off. Well, that's a no brainer, but thankfully he seems a bit freer in movement already. Hopefully time will tell and things will just keep improving.

The funny thing is, though, that horses with Cushings typically are hypothyroid, so how can a horse with an overactive thyroid gland have Cushings? But, we'll see within the next couple weeks if Gus indeed has it. I really hope not, but then again, that would just be icing on the cake, right? Then back to CoTH for diet recommendations. Sheesh. I seriously hope that's not the case.

I hope we find something to get him better. This overactive thyroid isn't bothering him too much, from what we can gather. He did have a fine needle aspirate done of his thyroid gland a couple years back. Results were inconclusive... but did not rule out the possiblity of something such as cancer/tumor. Decided to not persue that at the time. He's happy. I don't really want to know that something may be slowing cutting down his life expectancy. Plus, I will not put him thru surgery on his neck... it's a very hard place to suture up and well, he's not a good patient.

So, we'll see what the future holds. Now I'm off to email the vet, again. :winkgrin: I know she just LOVES me. :lol:

[deltawave]

What does "Lip . . . . . 1+" mean? That the horse is lipemic. That's never normal, is it?

[appychik]

What does "Lip . . . . . 1+" mean? That the horse is lipemic. That's never normal, is it?

Uh, I don't know. It was what shows up on the bloodwork panel. I probably could find the original paperwork and scan it in, but that's what I had typed into his records... didn't abbreviate that.

What is lipemic? Suppose I could google, but he's always had bloodwork with that... +1.

[deltawave]

Lipemic means there is free fat in the blood, usually in the form of triglycerides. Ask your vet to explain it--I'm not an expert on the topic in horses but from what I gather it is never normal, and not a good thing, to have lipemia. Maybe 1+ is within an acceptable range for horses--I dunno. Hopefully someone here with more experience with lipemic horses can chime in. There's a link, I believe, with metabolic syndrome and other maladies. Sorry I can't offer much more actual knowledge.

[appychik]

Lipemic means there is free fat in the blood, usually in the form of triglycerides. Ask your vet to explain it--I'm not an expert on the topic in horses but from what I gather it is never normal, and not a good thing, to have lipemia. Maybe 1+ is within an acceptable range for horses--I dunno. Hopefully someone here with more experience with lipemic horses can chime in. There's a link, I believe, with metabolic syndrome and other maladies. Sorry I can't offer much more actual knowledge.

Thanks deltawave. I do appreciate your input. I'll ask my vet to see if she knows at all (still waiting to hear back from them again). I'll post the response just as soon as I find out.

[cloudyandcallie]

The vet who diagnosed the old horse at our previous barn said it is unusual to have a hyperthyorid and cushings, but there are cases. That old horse had not had very good vet care prior to arriving at that barn.

He was tested and found to have cushings, and hyperthyroidism. But when treated for cushing, he lost more weight. (He was already very skinny, but had the long hair and didn't shed in the springtime, etc.)

I'd put Gus on rice bran or omega shine if they can be used on a cushings horse. Or use Buckeye's Ultimate Finish to help him gain weight.

[appychik]

The vet who diagnosed the old horse at our previous barn said it is unusual to have a hyperthyorid and cushings, but there are cases. That old horse had not had very good vet care prior to arriving at that barn.

He was tested and found to have cushings, and hyperthyroidism. But when treated for cushing, he lost more weight. (He was already very skinny, but had the long hair and didn't shed in the springtime, etc.)

I'd put Gus on rice bran or omega shine if they can be used on a cushings horse. Or use Buckeye's Ultimate Finish to help him gain weight.

I've started him back on 1/4 c. of OHS daily... He's really not needing the weight right now, actually looks pretty darn good despite everything (not fond of the round bale outside, not in work, eating a TON). If he really starts dropping the weight, I like to add Cool Calories. Unfortunately (unless the bloodwork tells otherwise) the BO does not like to feed separate feeds. So, unless it can be prebagged up, she won't feed anything but the three feeds available - Patriot Feed Easy (forget the percentage), Patriot's Senior or Junior versions. That's all that's available, unfortunately.

I'm really hoping that the ACTH comes back within normal limits, but alas I have a hunch that that won't be the case. So, we'll be back to the drawing boards then. Haven't tested yet, so I am getting a head of myself. Should know within the next couple weeks as the test should be here any day now (or should I say the injections they use for the test).

It is interesting about the horse being hyperthyroid and having Cushings. I just didn't think that was possible, but then again, anything is... especially when it comes to horses. ;) ETA: ESPECIALLY my horses!