Serum Thyroid Hormone and Thyrotropin Concentrations in Adult Horses as They Age.
Abstract: With more horses remaining active longer in life, it is important to characterize changes that occur normally with aging, so that these can be differentiated from development of disease. The objective of the study was to test the hypotheses that geriatric horses have lower circulating concentrations of thyroid hormones and/or higher serum thyrotropin (TSH) concentrations compared to younger horses. Serum thyroid hormone and TSH concentrations from 71 normal, healthy horses that had participated in prior research projects were analyzed for effects of age, sex, and season when samples were obtained. All samples had been assayed in the same previously validated radioimmunoassays. There were no differences in serum concentrations of thyroid hormones or TSH by sex or season. Serum total thyroxine (T4) was greater in 3- to 6-year-old horses compared to all other age groups and was negatively correlated with age. There were no differences among age groups for free T4 and total and free tri-iodothyronine (T3). Serum TSH concentration was significantly greater in old horses (≥15 or ≥20 years) compared to young (3-10 years) and intermediate (11-14 years) age groups. Serum TSH was positively correlated with age. There were no significant differences in thyroid hormone responses to thyrotropin releasing hormone (TRH) among young, intermediate, or old horses. However, the TSH response to TRH was significantly different in both groups of older horses compared to intermediate and young horses. Serum total thyroxine concentrations decrease and serum TSH concentrations increase in horses as they age, with no changes in free T4 or T3.
Copyright © 2018 Elsevier Inc. All rights reserved.
Publication Date: 2018-04-30 PubMed ID: 31256883DOI: 10.1016/j.jevs.2018.04.006Google Scholar: Lookup
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- Journal Article
Summary
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The research study investigates the changes in thyroid hormones and thyrotropin concentrations in horses as they age, with evidence showing total thyroxine in the serum decreases and thyrotropin numbers increase with age.
Objective and Hypothesis of the Research
- The main goal of this study was to understand the alterations that occur in the serum thyroid hormone and thyrotropin (TSH) concentrations of horses as they grow older. This is based on the observation that more horses are staying active as they age.
- The primary hypothesis was that older horses have lower circulating concentrations of thyroid hormones and/or higher serum TSH concentrations in comparison to younger horses.
Methodology
- The researchers conducted their study on 71 normal, healthy horses that had participated in earlier research studies.
- All the samples had been analyzed using the same validated radioimmunoassays.
- The effects of age, sex, and the season when samples were obtained were all taken into account.
Results
- The study didn’t find any significant changes in the concentration of serum thyroid hormones or TSH based on the sex or season of the horses.
- Horses between 3-6 years had higher total thyroxine (T4) concentration compared to other age groups, with a decrease in its concentration with age.
- The serum TSH concentration was significantly higher in older horses (those aged ≥15 or ≥20 years) in comparison to the young (3-10 years) and intermediate (11-14 years) age groups. The concentration of TSH was seen to increase with age.
- No significant differences were observed in the responses of thyroid hormone to thyrotropin-releasing hormone (TRH) among different age groups. Nonetheless, the TSH response to TRH was notably different in older horses compared to intermediate and young ones.
Conclusion
- The results of the study show that as horses age, there is a decrease in serum total thyroxine concentrations and an increase in serum TSH concentrations. However, no changes were observed in free T4 or T3.
Cite This Article
APA
Breuhaus BA.
(2018).
Serum Thyroid Hormone and Thyrotropin Concentrations in Adult Horses as They Age.
J Equine Vet Sci, 68, 21-25.
https://doi.org/10.1016/j.jevs.2018.04.006 Publication
Researcher Affiliations
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC. Electronic address: betta_breuhaus@ncsu.edu.
Citations
This article has been cited 3 times.- Ahmadi F, Mirshahi A, Mohri M, Sardari K, Sharifi K. Osteochondrosis dissecans (OCD) in horses: hormonal and biochemical study (19 cases). Vet Res Forum 2021;12(3):325-331.
- Ferlazzo A, Cravana C, Fazio E, Medica P. The different hormonal system during exercise stress coping in horses. Vet World 2020 May;13(5):847-859.
- Viviani P, Lavado RA, Chavarria NH, Ragno VM, Montgomery JB. Spring and fall blood concentrations of adrenocorticotropic hormone, insulin, and thyroxine in healthy horses in Saskatchewan. Can Vet J 2024 Apr;65(4):335-342.
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