Dog with steroid-induced Cushing's disease and low thyroid hormone

Abstract

The canine hypothyroidism corresponds to a hormonal disorder, mainly caused by destruction of the thyroid gland, followed by idiopathic thyroid degeneration or idiopathic follicular atrophy, leading to a low production of the hormones thyroxine (T4) and triiodothyronine (T3). The canine iatrogenic hyperadrenocorticism consists of a disorder caused by the prolonged use of corticosteroids for therapeutic purposes, in most cases in allergic processes, such as canine atopy. In this case report, a twelve-year-old female Schnauzer was presented to the clinical facility with signs of apathy, polyphagia and non-pruritic bilateral symmetric alopecia that extended to the tip of the tail but sparing the head and limbs. Other clinical manifestations included polyuria, polydipsia, and bilateral keratoconjunctivitis sicca. The animal was submitted to the blood count, T4, T3, TSH dosage, dexamethasone suppression test, biochemical tests, and imaging tests. Exam results demonstrate the presence of hyperadrenocorticism and hypothyroidism. Since the use of corticosteroids in canine allergic diseases can lead to the development of hyperadrenocorticism, and hypothyroidism corresponds to the most common endocrinopathy in dogs, it is essential that the clinical veterinarian is able to identify these diseases early.