This is an archived Horseadvice.com Discussion. The parent article and menus are available on the navigation menu below:
HorseAdvice.com » Diseases of Horses » Endocrine System » Hypothyroidism in Foals »
  Discussion on Hypothytoid Foal in Thyroid Supplemented Mare
Author Message

Posted on Tuesday, Sep 19, 2000 - 1:36 pm:

I have a 6 mo old TB foal with a large goiter. Her mother was give Thyrol L 2 tsp. 1 x daily during pregnancy. Blood tests wer done periodically to make sure the proper amount was given. When she was born, she had the typical glossy coat and undershot jaw. However, she did not have any musculoskeletal problems. While she was in Ky. for the breeding season with her mother, the goiter never subsided. It does not seem to bother her, but for resale I have my doubts. Besides the salt and perhaps an ultrasound, is there any other way of reducing the size of the goiter?

Posted on Wednesday, Sep 20, 2000 - 6:08 am:

Hello Judith,
Perhaps there is. What is the basis for the diagnosis of hypothyroidism in the mare?
DrO

Posted on Wednesday, Sep 20, 2000 - 4:31 pm:

While she was in Ky. in 98, 99, & 2000 the majoity of the farms automatically put The mares on Thyrol L before breeding. I am assuming they take the "T" tests, but from what I have read they are not very reliable.

This is the first foal with a goiter. Apparently there is a cross-over to the foal if to much Thyrol L has been given. I gave what the local veterinarians felt was an adequate dose, again relying on "T3 & T4" tests. This was given through her pregnancy.

The goiter is a little smaller than a tennis ball, on both sides. Any info will be more than appreciated.

Posted on Thursday, Sep 21, 2000 - 8:56 am:

No kidding the majority of mares are put on thyroid supplement(?): You would think in KY they would know better up there.

You know when I first read this post, I said to myself: yep a complication of thyroid supplementatiion. But the more I think about it the less sure I am. Goitre is usually caused by the thyroid gland trying to make hormone but dietary or toxic factors preventing completion or preventing its release. The result is increase stimulation to the thyroid (TSH) and it enlarges. Most frequently this is from iodine metabolism abnormalities.

In the past iodine deficiency was the common cause and mares have had unexplainable goiter problems in foals presumably from iodine deficiency even when other unaffected mares and iodine supplemented salts were available.

In recent years over supplementation of iodine has become the most common cause of goiter. Excess intake of iodized salts, seaweed supplements, and some forms of organic iodine used as a antibiotic are possible though uncommon problems. Perhaps you should evaluate the diet and supplements for iodine content to be sure supplementation is the right way to go. Of course what the mare received during gestation is of interest.

If not severe and with little more than proper care these do usually go away. A goitre indicates that the body thinks there is not enough thyroid hormone circulating so thyroid supplement is also rationale treatment.
DrO

Posted on Saturday, Sep 23, 2000 - 5:30 pm:

Wow...and how do I find this out? A TSH test? I am really confused. I thought over supplementation of the mare during pregnancy was the cause of the foal's goiter. I did see a yearling go through the Saratoga sale with a goiter...brought $150,000 and that sale requires a complete physical exam and radiographs for the repository. I think the TSH test is the way to go...agree?

Judy

Posted on Saturday, Sep 23, 2000 - 5:51 pm:

Yes we believe it provides the best answers but require difficult to get hormones and expensive assays. I would look carefully at all the facts surrounding the case: diet, supplements, testing, and history and see if something logical does not fall out.
DrO
Home Page | Top of Page | Join Us!
Horseadvice.com is a BBB Accredited Business. Click for the BBB Business Review of this Horse Training in Stokesdale NC