Background: There is a significant possibility that an incorrect diagnosis of hypothyroidism could be made in euthyroid patients, and the prevalence of hypothyroidism in the dog population remains controversial.
Objectives: To retrospectively assess the percentage of dogs diagnosed with, and treated for, hypothyroidism at first opinion practice which are likely to be truly hypothyroid and require levothyroxine supplementation.
Animals: 102 dogs were included in this study.
Material and methods: The computerized databases of seven first opinion practices were searched, to identify dogs treated with levothyroxine supplementation. Three ECVIM-CA diplomates independently assigned one of four clinical assessments to each case as follows: confirmed or very likely hypothyroid, hypothyroidism suspected but not confirmed, hypothyroidism considered unlikely, and no reason to suspect hypothyroidism. They commented as to whether or not they thought levothyroxine supplementation was appropriate.
Results: The measure of serum total T4 concentration was not specifically requested by the veterinarian in 30 cases (29.4%). The clinical assessments of ‘confirmed or very likely hypothyroid’; 'Hypothyroidism suspected but not confirmed’; 'Hypothyroidism considered unlikely’; and ‘No reason to suspect hypothyroidism’ was assigned respectively by Clinician 1 to 38.2%, 5.9%, 3.9%, and 52% of cases, by Clinician 2 to 48%, 22.55%, 22.55%, 6.9% of cases, and by Clinician 3 to 55.9%, 11.8%, 13.7% and 18.6%. Clinician 1, Clinician 2, and Clinician 3 considered levothyroxine supplementation not indicated in 56.9%, 53.9%, and 45.1% of cases, respectively.
Conclusion: These results support the concern that hypothyroidism might be overly and incorrectly diagnosed in first opinion practice.
