hypothyroid question

[shoulderin]

I saw in a post on laminitis in the farrier bulletin that
calshoer knew a lot of hypothryoid horses - so
I hope calshoer see this question and others who
are knowedeable -

I have a horse that foundered in Aug o4. She tested
low on thyroid - vet put her on thyroid-l once scoop
a day - (looks like about 1/2 teaspoon) - her thyroid
levels now test a little on the high side -- vet says
this could have been the laminitis trigger - (but she
was given a shot of penicillion - which was turned out
to be badly allergic to - and she foundered right after - and
on the left front where the shot was given ) I think the
shot caused it - but vet blames thyroid level and he
diagnosed her as hypothyroid based on the one thyroid
test.
heres my question -= my horse shows no symptions
of being hypothyroid - not a single one - she is and
always has been in good weight - never even close to fat
but not skinny - good flesh and all muscle - very high
energy (if anything she would be closer to hyperthypoid )
her skin and coat are lovely - even when she was in acute
founder stages she looked good. I read a ton of articles
on hypothyroid - they all said it was "extremely rare in horse and over diagnosed" - these were vet school
journals.

Do any of you know if a horse can be hyporthyroid
and not have any symptions other than a low thyroid
test result (which I also read were unreliable)

[calshoer]

Dr Myers should probably answer this in more detail but I will give you some very general ideas.
BTW I am certainly not any kind of expert on horses endocrine sytem, I simply gather all the information I can from various dicussion forums and veterinary sources becaue I treat so much metabicially induced laminitis.
There are many things that can cause the thyroid to test low...it is a common side effect of other promary metabolic isues such as indsulin resistance. Bute can also cause a temporary low thryroid test.
It is becoming more recognized in the veterinary field that a low thyroid is usually NOT the primary cause of the laminitis. It is more often just a seconary symptom of something else.
Triggers of the laminitis could include the reaction to the antibiotic, or to some other mdication she was given such as bute ,or cortiozone.Or whatever she got the antibiotic for in the first place. Horses can get get laminitis when given antibiotics and bute at the same time . It upsets their normal healhy gut bacteria, irritates the gut lining and thereby allows gut toxins into the bloodstream. .
Cortizone is another very likely laminitis trigger, was she given that drug to counteract the allergic reaction to the antibiotic? (and why was she given an antibiotic in the first place???.
Go to yahoo .com, click on "Groups" and join the EquineCushings discussion. it is free.There is a lot of knowledgeable people there including Dr Kellon who can probably help even if your horse is not does not have Cushings.
Dr Meyers can you add anything? Patty

[shoulderin]

Patty -
thank you for your reply - I didn't realize I posted
this in the farriers helping farriers forums - jeez -
I keep getting lost in the board - I meant to post
in the helping owners --
My horse had a yellow snotty nose - she wasn't
feeling bad but the vet thought he would "knock it out"
with a dose of penicillion. She had an allergic reaction to
that - her whole left shoulder - halfway up her neck
and down her left leg swelled up over the next 2-3 days.
She moved stiffly then (from the swelling from this
reaction we thought) - then about 4 days later - swelling
all gone - but shes moving even a little stiffer on left
front and I could tell she was feeling bad - I immediately
took her in to clinic - she had founderd in left front and
it was starting up in the right.

My vet says he thinks since she tested low on the thyoid levels then that was the cause of the founder -- no matter
she has no symptoms - he says the founder IS THE
sympton. If she is truly hypothyroid then I feel all her
recovery is probally short lived - truly hypothyroid horses
tend to just recover and refounder over and over. It thats
the case I won't let her go thought that - next time it
happens I will have her put down. So I really would
like a definitive diagnosis if its possible. I just had the
throid test rerun last week - two different test - one
was a new / better test than T3/T4 - and the old t3/t4
rerun - vet said results were both a little on the high
side of normal (26 on the 36 scale I believe) and
(2.6 on the 0-3 scale) - she is on 1 scoop of throid l
daily.

Maybe Dr. Myers will see this an offer a suggestion
if she/he feels my horse could be hypothroid or if
if sounds she may not be -- or how I can determine
this .

Sorry this is so long.
Thanks again patty.

[mwmyersdvm]

To date there appears to be a consensus that primary hypothyroidism does not occur in the horse. I view low thyroid as an indicator of equine metabolic syndrome or a pre-cushingoid state. These horses can appear and act quite normally, but are VERY sensitive to incorrect diets and high carbohydrate pastures and hay.
Adding thyroid probably works by entering this hormone into the pituitary feedback hormonal loop and altering some of the other hormone outputs in the mix.
I would test the insulin level on this horse through BET labs as a screen, but would be careful on how this hoprse is fed even if this is normal. Check out Katy Watts site, www.safergrass.org.

M. W. Myers, D.V.M.

[calshoer]

Thank you for the input. Since I am not a veterinarian I am a bit uncomfortable stepping too far on these type of questions. Your qualified veterinary input here on these boards is invaluable. Patty

[shoulderin]

thanks Dr. Myers -
I think I will ask my vet to run the insulin test -
He has never suggested this - but I did read
all about the metaboic disorder and IR -
It could be there is an underlying Insulin problem -
again , thanks for your response.