Thyroid hormone concentrations returned to normal after phenobarbital was stopped. These effects must be considered when testing thyroid function in dogs taking phenobarbital. Potassium bromide, another commonly used antiseizure drug, does not seem to affect thyroid hormone levels. At appropriate doses, treatment is effective and safe. Considering the adverse effects on health caused by low thyroid function, dogs with epilepsy and hypothyroidism should be treated regardless of any potential association between hypothyroidism and epilepsy.
Treatment is indicated only when the diagnosis has been confirmed by appropriate laboratory testing.
Empiric treatment of epilepsy with thyroid supplementation is not indicated in the absence of documented hypothyroidism. WB Thomas DVM Dipl. University of Tennessee Knoxville, TN References 1. Effects of long-term phenobarbital treatment on the thyroid and adrenal axis and adrenal function tests in dogs. Thyroid function and serum hepatic enzyme activity in dogs after phenobarbital administration.