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Synthesis and Regulation of Thyroid Hormones

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Related Experiment Video

Updated: May 19, 2026

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids

Published on: April 25, 2016

Thyroid hormone concentrations differ between donkeys and horses.

F J Mendoza¹, R A Perez-Ecija, R E Toribio

¹Department of Animal Medicine and Surgery, Universidad of Cordoba, Spain. pv2megaf@uco.es

Equine Veterinary Journal

|August 23, 2012

Summary

This summary is machine-generated.

Thyroid hormone levels differ significantly between donkeys and horses. Age impacts hormone concentrations in donkeys, with younger animals showing higher levels of certain hormones. Species-specific ranges are crucial for accurate diagnosis.

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Area of Science:

Veterinary Endocrinology
Comparative Physiology

Background:

Establishing reference intervals for thyroid hormones (TH) in donkeys is essential to prevent misdiagnosis of thyroid disease.
Current knowledge gaps exist regarding normal TH concentrations in donkeys.

Purpose of the Study:

To determine normal thyroid hormone values in healthy adult donkeys.
To compare donkey TH values with those of healthy adult horses.

Main Methods:

Serum concentrations of free triiodothyronine (fT3), total triiodothyronine (tT3), reverse triiodothyronine (rT3), free thyroxine (fT4), and total thyroxine (tT4) were measured in 38 donkeys and 19 horses using radioimmunoassay.
Donkeys were categorized into age groups (<5, 5-10, >11 years) and gender groups.
Statistical analysis included one-way ANOVA and Fisher's LSD test, with P<0.05 considered significant.

Main Results:

Donkeys exhibited higher serum TH concentrations compared to horses (P<0.01).
Younger donkeys (<5 years) had elevated rT3, fT4, and tT4 levels compared to older donkeys (>5 years).
Older donkeys (>11 years) showed lower fT3 and tT3 concentrations than younger age groups; no significant gender-based differences were observed.

Conclusions:

Significant differences in thyroid hormone concentrations exist between healthy adult donkeys and horses.
Species-specific reference ranges for TH are critical for accurate diagnosis of thyroid dysfunction in equids.
Further research is needed to understand the physiological basis for these interspecies differences.