Thyroid function and motor activity in dogs during development

Abstract

The intensity of motor activity and the serum level of protein-bound iodine (PBI) were investigated in 62 puppies aged from 1 to 12 months. During the first 4 months of life a parallel increase in motor activity and PBI of the puppies was observed. The increase in motor activity of puppies between the ages of 7 and 9 months was not accompanied by any increase in PBI. In hypothyroidism caused by methimazole in puppies aged 1 and 3 months increased motor activity was observed, whereas in animals aged 7 months it was reduced. A higher intensity of motor activity than in the control animals also was observed 1 month after the operation in puppies thyroidectomized at the ages of 1 and 3.5 months. The activity of puppies thyroidectomized at the age of 1 month was sharply reduced 2–4 months after the operation. In dogs thyroidectomized at the ages of 7.5 and 11.5 months, reduced activity was observed as early as 1 month after the operation. The data showing opposite effects of thyroid hormones on the behavior of puppies at different ages point to a complex relationship between motor activity and thyroid function.