Open AccessEffects of Toceranib Phosphate on the Hypothalamic‐Pituitary‐Thyroid Axis in Tumor‐Bearing Dogs
Author(s) -
Hume K.R.,
Rizzo V.L.,
Cawley J.R.,
Balkman C.E.
Publication year - 2017
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/jvim.14882
Subject(s) - medicine , endocrinology , triiodothyronine , thyroglobulin , thyroid , hormone , confidence interval , thyroid stimulating hormone , hypothalamic–pituitary–thyroid axis , prospective cohort study
Background Thyroid dysfunction is associated with the use of tyrosine kinase inhibitors ( TKI ) in people. Hypothesis/Objectives To determine whether dysfunction in the hypothalamic‐pituitary‐thyroid axis occurs in dogs receiving the TKI , toceranib phosphate. Animals Forty‐three client‐owned dogs with cancer. Methods Prospective, observational study. Concentrations of total thyroxine ( TT 4), free thyroxine ( FT 4), total triiodothyronine ( TT 3), and thyroid‐stimulating hormone ( TSH ) were evaluated on day 0, 30, and 90. Dogs also were evaluated for the presence of thyroglobulin autoantibodies. Results The proportion of dogs with low TT 4, low FT 4, low TT 3, high TSH , or primary hypothyroidism (increased TSH and decreased TT 4, FT 4 or both) did not change over 90 days. Hormone concentrations remained within laboratory reference intervals, but FT 4 ( P = 0.0032) and TSH ( P < 0.0001) changed over time. Mean FT 4 was 1.22 ng/ dL (95% confidence interval [ CI ], 1.10–1.34) on day 0 and 1.00 ng/ dL (95% CI , 0.86–1.16) on day 90. Mean TSH was 0.17 ng/ mL (95% CI , 0.13–0.23) on day 0 and 0.34 ng/ mL (95% CI , 0.24–0.48) on day 90. Furthermore, TT 4/ TT 3 ratio also changed over time ( P = 0.0086). Mean TT 4/ TT 3 ratio was 2.57 (95% CI , 2.26–2.88) on day 0 and 2.02 on day 90 (95% CI , 1.61–2.44). Thyroglobulin autoantibodies were not detected in any dog. Conclusions and Clinical Importance Toceranib phosphate can disrupt the hypothalamic‐pituitary‐thyroid axis in dogs. Periodic evaluation of TT 4, FT 4, TT 3, and TSH should be carried out in dogs receiving long‐term treatment with this medication.