Pharmacokinetics of total thyroxine after repeated oral administration of levothyroxine solution and its clinical efficacy in hypothyroid dogs.

Background: Oral levothyroxine (l-T4 ) supplementation is commonly used to treat hypothyroid dogs.

Objectives: Investigate the plasma profile and pharmacokinetics of total thyroxine (tT4 ) after PO administration of a l-T4 solution and its clinical efficacy in hypothyroid dogs.

Animals: Ten dogs with naturally occurring hypothyroidism.

[Treatment of feline hyperthyroidism with radioactive iodine-131].

Feline hyperthyroidism can be treated by thyroidectomy, antithyroid drugs, or radioactive iodine-131 (131I). The aim of this retrospective study was to evaluate the treatment of 83 hyperthyroid cats with 131I The dosage of 131I ranged from 4 to 6 milliCurie (mCi). Blood samples for determination of plasma concentrations of total thyroxine (TT4), urea, and creatinine were collected before, ten days after, and several months after treatment.