Biology Reference
In-Depth Information
to be hypothyroid, which means they have underactive thyroid glands.
Humans can have thyroid imbalances either way.
Signs of Hyperthyroidism
The thyroid gland produces hormones that have many different func-
tions.Their main purpose is to regulate metabolism.Thyroid hormone
affects every part of the body to some degree, but its major effects are
on the heart, skin and gastrointestinal tract.
The common clinical signs associated with hyperthyroidism are:
•
Weight loss
•
Increased appetite
•
Increased thirst
•
Increased urination
•
Increased heart rate and possibly irregular heartbeat
Owners might notice these changes in their cat, but often they are
discovered during a routine physical examination and discussion with a
veterinarian. If a veterinarian suspects your cat is hyperthyroid, she will
want to perform some blood tests.
Blood tests are good for pinpointing hyperthyroidism and for dif-
ferentiating the disease from other metabolic imbalances. If the thyroid
hormone level is not out of the normal range on a basic test, but clin-
ical signs suggest a problem, the veterinarian may want to perform
either a T3 suppression test or free T4 by equilibrium dialysis.A T3 sup-
pression test is a blood test that looks at whether the thyroid gland
reacts normally to the administration of supplemental thyroid hor-
mone. A normal cat's T4 values will go down in this situation, but a
hyperthyroid cat's will not. Free T4 by equilibrium dialysis is a blood
test that is felt to more accurately evaluate T4 levels. These tests are
straightforward but not without some false positives.
Finally, another test called a technicium scan may be required.This
test highlights the thyroid gland through special imaging and shows if
there is overactive tissue.
Treating Hyperthyroidism
Uncontrolled thyroid disease will lead to many problems. Aside from
poor general condition and a slow wasting process, a hyperthyroid cat
can develop serious heart disease. Heart disease occurs because the heart
