|Tests to diagnose
hypothyroidism usually involve blood work, where the veterinarian will check the
T3 or T4 level. When diagnosed, the common treatment consists of feed additives
containing thyroid hormones. Unfortunately, supplementing the feed if there is a
different condition at work in the horseís body may actually spell more trouble!
For example, if the body considers the supplementation to be excessive, the
thyroid may decide to decrease its normal production of hormones, thus actually
causing hypothyroidism. Add to this the fact that excessive supplementation in
humans has been linked to undesirable side effect, such as heart problems, and
you will have to agree that caution is warranted.
It is not surprising that because of these dangers this kind of testing has come
under scrutiny, since some kinds of these hormones may be deemed active while
others are considered inactive, yet they are still having a heavy bearing on the
outcome of the test. In addition to the foregoing, the administration of drugs
and even changes in feed may influence the levels of thyroid hormones. To make
matters worse for the testers, it has been discovered that within a horseís body
there is a complex system of hormonal regulation which directly affects the
thyroid gland. Thus, thyroid levels may fluctuate from hour to hour and day to
day, without this being an indication of hypothyroidism.
To this end, many horse aficionados have concluded that in order to receive an
accurate test result, there needs to be a periodic sampling of blood which takes
into account normal fluctuations. This will permit adequate treatments to be
undertaken, and it will avoid false-positive results that may lead to an
unnecessary treatment of the thyroid. Another test that has garnered a lot of
favor involves the administration of the thyroid stimulating hormone (TSH) which
occurs naturally in the horseís pituitary gland. During clinical tests
veterinarians will be able to ascertain the thyroid glandís response to the
increased TSH will in turn will give an accurate measurement of the glandís
level of functioning.
It is obvious that much more research is warranted. Similarly, because of the
adverse effects of misdiagnosis, it is imperative that thyroid supplementation
not take place based on guesses, but only cold, hard data which is further
supported by the horseís condition improving in response to treatment.