You're getting into an area where my knowledge is very limited. The TSH test
will determine how whell the thyroid gland responds to stimulous. If it
responds normally, then something else is causing your problems--perhaps a
zinc deficiency or other nutrient imbalance. I'd go along with your vet for a
while--she seems to be tuned in.
The thyroid gland, by the way, helps the body determine how fuels, and other
nutients, are used--and the speed at which they are used.
ti