How could you treat a thyroidectomized rat so that it functions like a normal rat? How would you verify that your treatments were safe and effective?

Inject it with thyroxine.

Explanation:

Thyroidectomy may be defined as the medical surgery in which the thyroid gland of an individual is removed from the body. This might removes in case of disease or cancer.

Thyroid gland releases the thyroxine hormone and triidothyronine that maintains the overall growth and metabolism of an individual. The thyroidectomized rat lacks the thyroid gland. The rats need the supply of the thyroxine hormone from the external medium.

Thus, the answer is inject it with thyroxine.