Effect of Levothyroxine Administration on Hemostatic Analytes in Doberman Pinschers with von Willebrand's Disease

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dc.contributor.authorHeseltine-Heal, Johanna Colleenen
dc.contributor.committeechairPanciera, David L.en
dc.contributor.committeememberMonroe, William E.en
dc.contributor.committeememberFeldman, Bernard F.en
dc.contributor.committeememberTroy, Gregory C.en
dc.contributor.departmentVeterinary Medical Sciencesen
dc.date.accessioned2014-03-14T20:34:59Zen
dc.date.adate2004-05-10en
dc.date.available2014-03-14T20:34:59Zen
dc.date.issued2004-04-23en
dc.date.rdate2005-05-10en
dc.date.sdate2004-05-04en
dc.description.abstractThis study tested the hypothesis that levothyroxine supplementation increases plasma von Willebrand factor (vWf) concentration and enhances vWf function. The effects of levothyroxine administration were evaluated in 8 euthyroid Doberman Pinschers with plasma vWf concentration <30%. Levothyroxine (0.04mg/kg PO q12hours) and placebo were administered for 30 days in a 2-period, 2-treatment, double-blinded, crossover design with a 30-day washout period between treatments. Buccal mucosal bleeding time (BMBT), vWf antigen concentration (vWf:Ag), vWf collagen binding activity (vWf:CBA), Factor VIII coagulant activity (FVIII:C), serum total thyroxine (T4), free thyroxine (fT4), 3,5,3รข -triiodothyronine (T3), and thyroid stimulating hormone were measured on days 0, 2, and 30 of each treatment period. The dogs had markedly low plasma vWf:Ag concentrations (mean 8.9%; reference range 70-180%) and vWf:CBA (mean 11.1%; reference range >70%). All dogs had FVIII:C activity within reference range. The response to placebo versus active levothyroxine treatment revealed no significant differences between groups at any time for BMBT, vWf:Ag, vWf:CBA, and FVIII:C. Serum total thyroxine, fT4, and T3 were significantly higher in the levothyroxine-treated group compared to the placebo group at days 2 and 30. Thyroid stimulating hormone was significantly lower in the levothyroxine-treated group compared to the placebo group at days 2 and 30. Levothyroxine (0.04mg/kg) caused laboratory evidence of hyperthyroidism but did not affect plasma FVIII:C and vWf:Ag concentration or the vWf-dependent functional parameters of collagen binding and BMBT. The results of this study do not reveal a direct action of levothyroxine supplementation on plasma vWf concentration or activity in euthyroid Doberman Pinschers.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-05042004-224809en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05042004-224809/en
dc.identifier.urihttp://hdl.handle.net/10919/32178en
dc.publisherVirginia Techen
dc.relation.haspartHeseltine_MSThesis_.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectlevothyroxineen
dc.subjectthyroiden
dc.subjectcanineen
dc.subjectvon Willebrand's diseaseen
dc.subjectvon Willebrand factoren
dc.titleEffect of Levothyroxine Administration on Hemostatic Analytes in Doberman Pinschers with von Willebrand's Diseaseen
dc.typeThesisen
thesis.degree.disciplineVeterinary Medical Sciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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