How would you approach diagnosing canine hypothyroidism and interpreting borderline T4 results in a sick patient?

• A. Order total T4 as initial screen; if sick patient or borderline results, repeat as free T4 by equilibrium dialysis or TSH stimulation test to confirm true hypothyroidism.
• B. Only measure TSH levels.
• C. Rely on clinical signs alone without testing.
• D. Skip testing and treat empirically.

Answer: (A)