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Treatment and therapeutic monitoring of canine hypothyroidism
Author(s) -
Dixon R. M.,
Reid S. W. J.,
Mooney C. T.
Publication year - 2002
Publication title -
journal of small animal practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.7
H-Index - 67
eISSN - 1748-5827
pISSN - 0022-4510
DOI - 10.1111/j.1748-5827.2002.tb00082.x
Subject(s) - medicine , lethargy , liter , interquartile range , thyroid , hormone , therapeutic index , gastroenterology , reference range , endocrinology , physiology , pharmacology , drug
Thirty‐one dogs with spontaneous hypothyroidism were treated with thyroid hormone replacement therapy (THRT) and monitored for approximately three months. Good clinical and laboratory control was ultimately achieved in all cases with a mean L‐thyroxine (T 4 ) dose of 0·026 mg/kg administered once daily. There was a significant increase and decrease in circulating total T 4 and canine thyroid stimulating hormone (cTSH) concentrations, respectively, after starting THRT. After commencing treatment, 11 cases subsequently required an increase and three cases required a decrease in dose to achieve optimal clinical control. Median (semi interquartile range [SIR]) circulating six‐hour post‐pill total T 4 (53·6 [27·9] nmol/litre) and cTSH (0·03 [0] μg/litre) concentrations were significantly increased and decreased, respectively, in treated dogs that did not require a dose change; corresponding values in treated dogs in which an increase in dose was required were 29·3 (12·7) nmol/litre and 0·15 (0·62) μg/litre, respectively. However, circulating cTSH measurement was of limited value in assessing therapeutic control because, although increased values were associated with inadequate therapy, reference range cTSH values were common in inadequately treated dogs. Lethargy and mental demeanour were typically the first clinical signs to improve, with significant bodyweight reduction occurring within two weeks of commencing THRT. Routine clinicopathological monitoring was of value in confirming a general metabolic response to THRT, but was of limited value in accurately monitoring cases or tailoring therapy in individual cases.