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  Discussion on Hypothyroid Adult Horse and Need for Testing
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New Member:
Sjeys

Posted on Tuesday, Feb 15, 2005 - 1:01 pm:

I have a 25 year old, retired, Grey TB Gelding that I have owned for 8 years. He has extensive Melanoma throughout his body. A few weeks ago he got violently ill, sweating, shaking, no appetite. Everyone thought he might die or have to be put down. We ran every lab we could think of and the only thing that came back out of the ordinary was a very low Thyroid (T3 and T4). Almost off the scale low. So my vet suggested Thyro-L which he is now on.

He certainly fits the description of hypothyroid: very thin, appetite that wains on and off, days of being dull and listless, bad coat.

I know Hypothyroid is incredibly rare, but the reason I am posting is because I have seen a marked improvement in his attitude; he is quite a bit 'brighter' and certainly a lot more vocal since being put on Thyro-L about 3 weeks ago.

So, if the "cure" is to keep him on Thyro-L, should I bother with the definitive tests that tell me this is definitely the cause? Or is this rare enough to warrant a confirmation? I don't like to subject my horses to needless supplementation.

If I do run these tests, how far in advance should I stop the Thyro-L in order to get an accurate reading? Thank you!
Moderator:
DrO

Posted on Tuesday, Feb 15, 2005 - 6:44 pm:

Hello Susan,
What were the thyroid levels and the normal range for your lab? Also are there any signs of Cushingnoid disease?

If your horse was so ill and the response so remarkable I would not consider removing the medication without a clearer understanding of what is going on. With the extensive melanoma, I don't think pursuing further thyroid tests that important.
DrO
Member:
Sjeys

Posted on Wednesday, Feb 16, 2005 - 3:57 pm:

Thyroid Levels:

T3 RIA 28 (low) Normal 50-165
T4 RIA .61 (low) Normal 1.0-3.0
Free T4 .43 No normal range given.

Due to the his poor circulation, about once every couple of years, this horse gets a giant lymphagitis attack (as big as a stove pipe)in one of his hind back legs. We'd been almost completely recovered from one these milder attacks when he started going downhill. We were able to ascertain that he had injured his stifle after we managed to get him back on his feet. How is a mystery since this is a slow moving horse.

I believe the low thyroid is secondary to his tanking so badly a few weeks ago. In other words, he started to come back from death's doorstep a few days before putting him on Thyro-L. The Thyro-L though has managed to make him behave like he's about 5 years younger--brighter and more vocal.

Thank you for your response.

Moderator:
DrO

Posted on Thursday, Feb 17, 2005 - 7:25 am:

Your symptoms and blood work are supportive of the diagnosis and you saw a response: I would keep treating. To check I would run tests while being treated. If the numbers come up to normal you try to wean off the Thyro-L slowly checking periodically to measure results.

I would also pursue the possibility of Cushingnoid disease, the article is in this section on Endocrine Diseases.
DrO
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