A 7-year-old, spayed female, Yorkshire terrier dog with polyuria/polydipsia (PU/PD), interdigital edema, pruritus and abdominal enlargement was referred to the Veterinary Medical Teaching Hospital of the present university. Pituitary-dependent hyperadrenocortisim (PDH) was diagnosed by clinical signs, physical examination, laboratory examination (complete blood count, serum chemistry, urinalysis, ACTH stimulation test and high dose dexamethasone suppression test) and diagnostic imaging (radiography, ultrasonography and computed tomography). Clinical signs were improved after trilostane treatment, and maintenance therapy with trilostane still continued after successful induction therapy. Trilostane can be used as an alternative to mitotane therapy in hyperadrenocortisim in dogs.