This 20-year-old pony mare presents for evaluation of polydipsia and forelimb lameness. Examination of the feet reveals chronic laminitis and a sole abscess. Blood work reveals a stress leukogram and hyperglycemia. Which additional diagnostic test may solidify a diagnosis for this pony?

a) Thyroid hormone panel

b) Dexamethasone suppression test

c) Serologic viral titer panel

d) Serum fructosamine concentration