Effects of competitive and noncompetitive showjumping on total and free iodothyronines, β-endorphin, ACTH and cortisol levels of horses.
Abstract: Limited knowledge exists about the differentiated effects of competitive and noncompetitive showjumping on thyroid function and relationships with hypothalamic-hypophysis-corticoadrenal hormones. Objective: To obtain preliminary data about differentiated effects of competitive and noncompetitive showjumping on total and free iodothyronines, β-endorphin, ACTH and cortisol of horses. Methods: Five trained healthy jumper horses were studied during competitive and noncompetitive showjumping, performed in the same circuit design over 10 fences of 1.10 m. Hormone levels before, 5 and 30 min post exercise were recorded. Serum iodothyronines and cortisol concentrations were measured in duplicate utilising EIA kits. Serum ACTH and plasma β-endorphin concentrations were analysed in duplicate utilising RIA kits. Two-way RM ANOVA was applied to test for effects of interaction between different type of session and time. Significant differences between post exercise and basal values were established using Bonferroni's multiple comparison test. A linear correlation analysis (Pearson's method) was performed to analyse the relationships between total and free iodothyronines and between iodothyronines and β-endorphin, ACTH and cortisol. Results: In sampling times adopted no statistical different effects of type of session were recorded on hormone variables. Sampling time affected ACTH (F = 4.25; P < 0.02) and T(4) (F = 4.43; P < 0.02) post exercise changes. During the noncompetitive session, significant correlations existed between T(4) and β-endorphin (r = -0.56), ACTH (r = -0.65), between β-endorphin and ACTH (r = 0.52) and between T(3) and fT(3) (r = 0.72); during competition between β-endorphin and T(3) (r = -0.67), fT(3) (r = -0.59). Conclusions: These preliminary results could demonstrate correlations between thyroid hormones and β-endorphin response to showjumping, although no definitive conclusion can be produced concerning the relationships between HPA and thyroid function during exercise.
© 2010 EVJ Ltd.
Publication Date: 2011-05-27 PubMed ID: 21059003DOI: 10.1111/j.2042-3306.2010.00264.xGoogle Scholar: Lookup
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Summary
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The research article investigates how competitive and noncompetitive showjumping in horses affects their thyroid function and hormones related to stress. The study is preliminary and explores the relationship between certain hormones, but does not draw definitive conclusions about how physical exertion impacts the thyroid and stress hormones in horses.
Objective and Methods
- The primary objective of the study was to gather early data about the distinct effects of competitive and noncompetitive showjumping on hormone levels in horses. The hormones of interest were free and total iodothyronines (hormones produced by the thyroid gland), β-endorphin (a hormone that can influence mood and perceptions of pain), ACTH (a hormone that stimulates the production of cortisol, a stress hormone) and cortisol.
- The researchers studied five healthy jumper horses during both types of showjumping, which were performed on an identical 10-fence circuit. The horses’ hormone levels were recorded before, 5 minutes after, and 30 minutes after exercise.
- The levels of iodothyronines and cortisol in the horses’ blood serum were tested using an enzyme immunoassay (EIA), while levels of ACTH and β-endorphin were measured using a radioimmunoassay (RIA). Both are common laboratory techniques used to measure the concentration of specific substances.
- Trends and correlations between hormone levels were analyzed using two-way RM ANOVA (a statistical method to compare the means of two or more groups) and Pearson’s method for linear correlation analysis. Bonferroni’s multiple comparison test was used to determine significant differences between post-exercise and basal (inactive) hormone levels.
Results
- The results did not show any significant difference in the hormone levels between the two types of showjumping sessions.
- However, the time of sampling did have effects on ACTH and T4 (a form of iodothyronine) levels after the exercise.
- During the noncompetitive sessions, significant correlations were found between T4 and β-endorphin, T4 and ACTH, β-endorphin and ACTH, and between T3 (another form of iodothyronine) and fT3 (free T3).
- In the competitive sessions, significant correlations were observed between β-endorphin and both T3 and fT3.
Conclusions
- The research produced some preliminary evidence of correlations between thyroid hormones and β-endorphin in response to showjumping.
- However, the study could not establish conclusive relationships between the function of the hypothalamic-pituitary-adrenal (HPA) axis and thyroid during exercise. The HPA axis is the body’s central stress response system, and how it interacts with the thyroid functions during physically demanding tasks like showjumping is a question that this study attempted to explore.
- The study points towards a need for more research to thoroughly understand these hormonal interactions during physical exertion in horses.
Cite This Article
APA
Cravana C, Medica P, Prestopino M, Fazio E, Ferlazzo A.
(2011).
Effects of competitive and noncompetitive showjumping on total and free iodothyronines, β-endorphin, ACTH and cortisol levels of horses.
Equine Vet J Suppl(38), 179-184.
https://doi.org/10.1111/j.2042-3306.2010.00264.x Publication
Researcher Affiliations
- Department of Morphology, Unit of Veterinary Physiology, Faculty of Veterinary Medicine, Polo Universitario Annunziata, University of Messina, Messina, Italy. kricra@libero.it
MeSH Terms
- Adrenocorticotropic Hormone / blood
- Animals
- Heart Rate
- Horses / blood
- Horses / physiology
- Hydrocortisone / blood
- Physical Conditioning, Animal / physiology
- Sports
- Thyronines / blood
- beta-Endorphin / blood
Citations
This article has been cited 6 times.- Čebulj-Kadunc N, Frangež R, Kruljc P. Fluctuations of Physiological Variables during Conditioning of Lipizzan Fillies before Starting under Saddle. Animals (Basel) 2022 Mar 25;12(7).
- 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.
- Secombe CJ, Tan RHH, Perara DI, Byrne DP, Watts SP, Wearn JG. The Effect of Geographic Location on Circannual Adrenocorticotropic Hormone Plasma Concentrations in Horses in Australia. J Vet Intern Med 2017 Sep;31(5):1533-1540.
- Cravana C, Medica P, Ragonese G, Fazio E. Influence of training and competitive sessions on peripheral β-endorphin levels in training show jumping horses. Vet World 2017 Jan;10(1):67-73.
- Fazio E, Medica P, Cravana C, Ferlazzo AA. Pituitary-adrenocortical adjustments to transport stress in horses with previous different handling and transport conditions. Vet World 2016 Aug;9(8):856-61.
- Cravana C, Medica P, Fazio E, Satué K, Brancato G, La Fauci D, Bruschetta G. Circulating ACTH and Cortisol Investigations in Standardbred Racehorses Under Training and Racing Sessions. Vet Sci 2025 May 19;12(5).
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