title: Effect of oral administration of prednisolone on thyroid function in dogs.
abstract: To determine the effect of oral administration of prednisolone on thyroid function, 12 healthy Beagles were given 1.1 mg of prednisolone/kg of body weight every 12 hours for 22 days after 8 days of diagnostic testing of the dogs before treatment with prednisolone. Thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH) response tests were performed before treatment (days 1 and 8 of the study) and during treatment (days 21 and 28 of the study). Blood samples were collected daily at 8 AM and 2 and 8 PM to rule out normal daily hormone fluctuations as the cause of a potential decrease in serum triiodothyronine (T3), thyroxine (T4), and free T4 (fT4) concentrations. Serum T3, T4, and fT4 concentrations before treatment and 1 day and 21 days after the first prednisolone dose were compared by analyses of variance. Post-TSH and -TRH serum T3 and T4 concentrations before and during treatment were compared, using the Student t test for paired data. Oral administration of prednisolone significantly (P less than 0.005) decreased serum T3, T4, and fT4 concentrations in the 8 AM and 2 and 8 PM samples obtained 1 day and 21 days after the first prednisolone dose. Serum T4 and fT4 concentrations in 8 AM and 2 PM samples were significantly (P less than 0.05) lower 21 days after the first prednisolone dose than they were at 1 day after the first dose. Before treatment, serum T4 concentration in the 2 PM samples was significantly (P less than 0.05) higher than serum T4 concentration in 8 AM and 8 PM samples.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
authors.forename: S M
authors.initials: SM
authors.lastname: Torres
authors.forename: P J
authors.initials: PJ
authors.lastname: McKeever
authors.forename: S D
authors.initials: SD
authors.lastname: Johnston
mesh_terms: D000284:Administration, Oral; D000818:Animals; D004285:Dogs / Q000502:physiology*; D005260:Female; D008297:Male; D011239:Prednisolone / Q000008:administration & dosage / Q000494:pharmacology*; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D013974:Thyroxine / Q000097:blood / Q000378:metabolism; D014284:Triiodothyronine / Q000097:blood / Q000378:metabolism
chemical_list: D014284:Triiodothyronine; D011239:Prednisolone; D013974:Thyroxine