Clinical evaluation of the operative technique of total thyroidectomy in Wistar rats

Abstract

The total thyroidectomy operative technique can be fatal in murine models, and factors such as prolonged operative time, hemorrhages and iatrogenic injuries to the recurrent laryngeal nerve are commonly associated with significant trans and postoperative mortality. In order to reduce losses and, consequently, the number of animals being tested, the present study sought to establish clinical parameters for the surgical induction of hypothyroidism in rodents. Ten Wistar rats (Rattus norvegicus) were used, randomly distributed in two groups: Control (CG, n = 5), without surgical procedure and Hypothyroidism (HTG, n = 5), rats submitted to total thyroidectomy. At the beginning of the experimental period and at 60 days, blood samples were taken to determine serum concentrations of total T3, free T4, TSH and total calcium. The mean operative time, postoperative pain signs and rectal temperature were evaluated. The operative technique proved to be safe, without the occurrence of deaths. No pain symptoms were observed in the animals during the postoperative period. Likewise, there was no occurrence of iatrogenic hypoparathyroidism, attested by the normocalcemia of animals operated on at 60 days. The average initial operative time was reduced from 75.0 ± 1.57 to 33.3 ± 6.04 minutes. All thyroidectomized animals developed hypothyroidism, characterized by a statistically significant increase in serum TSH concentrations and a reduction in the concentrations of total T3 and free T4 (P < 0.05). It was concluded that total thyroidectomy in Wistar rats is a safe, reproducible and low-cost method. It is reiterated, however, the necessary surgical training in order to reduce losses and, consequently, the number of animals being tested.