Dermatological manifestations associated with canine hypothyroidism: A review

Canine endocrine dermatopathies account for 8.6% of the dermatological appointments, frequently presenting classic signs of non-pruritic bilaterally symmetrical alopecia that develops chronically. The most common are hypothyroidism, hyperadrenocorticism (HAC) and hyperestrogenism. Hypothyroidism is the most observed endocrine disease in dogs and it is characterized by a structural and / or functional abnormality in the gland, which leads to a deficient production of thyroid hormones. Clinical signs caused by insufficient thyroid hormones are commonly observed in the skin. Hormones produced by the thyroid are important in maintaining cutaneous function, once they perform a regulatory role in epidermal differentiation. Diagnosis of canine hypothyroidism is based on clinical and historical findings that are suggestive of the disease associated with supporting laboratory findings. The most frequently measured thyroid hormones are total tiroxine (TT4), total triiodothyronine (TT3) and free T4 (fT4). Skin biopsy may reveal histopathological findings highly suggestive of hypothyroidism such as vacuolization and arrector pili muscle hypertrophy. The combination of those knowledge is essential to the veterinarian when confronted with a chronic case of dermatological disorders, he or she may think about hypothyroidism as a possible diagnosis.