Link between hypothyroidism and diabetes in a dog case

Abstract

Hypothyroidism is the most common hormonal disorder in dogs because of the low production of the hormones thyroxine (T4) and triiodothyronine (T3) by the thyroid gland. The main cause of hypothyroidism in adult dogs is primary hypothyroidism associated with destruction of the thyroid gland in lymphocytic or autoimmune thyroiditis, followed by idiopathic thyroid degeneration or idiopathic follicular atrophy. Dogs affected by hypothyroidism may develop diabetes mellitus due to the propensity for the development of other endocrine diseases associated with the immune-mediated attack against cellular antigens associated with endocrine system. In this case report, an eleven-year-old male Lhasa Apso was presented to the clinical facility with signs of apathy, anorexia 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 cataracts. The animal was submitted to the blood count, T4, T3, TSH dosage, biochemical tests, and imaging tests (cervical and abdominal ultrasonography). Exam results demonstrate the presence of hypothyroidism and diabetes mellitus. Since hypothyroidism corresponds to the most common endocrine disorder in dogs, and they are prone to the development of diabetes mellitus, the veterinarian must be aware of the clinical manifestations of these diseases.