Caracterização de alterações clínico-patológicas de cães com hipotireoidismo induzido por metimazol

Abstract

The thyroid diseases have been showed even more frequently in veterinary medicine, mainly hypothyroidism. There aren t many studies in Brazil about clinical changes of iatrogenic hypothyroidism in dogs. Thus, new studies must be done about this endocrine disturb. The aim of this study was to identify the main clinical-pathological changes in iatrogenic methimazole-induced hypothyroidism in dogs. We used five adult mongrel dogs, submitted to methimazole (0.5 mg.kg-1) chronic oral treatment by 120 days. We collected blood samples to evaluate the serum levels of Total T4, Free T4 and canine TSH. In the same days of the collect of blood samples, we made skin biopsy to histopathology study. All samples were collected in the days 0, 60 and 120. (It was also evaluated the serum levels of cholesterol and triglycerides.) We even evaluated cholesterol and triglycerides serum levels. It was evidenced an increase in cholesterol and triglycerides levels. The Total T4 levels kept unchanged. Therefore, the Free T4 levels showed a decrease after the 120 days of treatment. Moreover, the TSH levels increased after the firsts 60 days. Our results show that pharmacological induction of hypothyroidism in dogs can be carried out by methimazole. New studies should be done using this experimental paradigm to determinate the appropriated dose of methimazole in dogs in order to induce more expressive clinical manifestations.