Making the distinction
Subclinical versus asymptomatic
The term subclinical hyperthyroidism arises from human medicine to indicate that although thyroid disease is present, the patient does not experience any clinical signs. In animals, this typically occurs at the earliest stages of disease. Because animals cannot express symptoms, we must instead rely on clinical signs. The term asymptomatic applies only to humans.
Occult versus overt
Occult hyperthyroidism occurs when clinical signs are present, but diagnostic test results are normal. Overt hyperthyroidism indicates compatible clinical signs and test results.