A Field Study of Serum, Colostrum, Milk Iodine, and Thyroid Hormone Concentrations in Postpartum Draft Mares and Foals.
Abstract: Iodine, thyroxine (T4) and triiodothyronine (T3) are required for normal fetal growth, maturation, and neonatal survival. There is a lack of robust information on iodine levels found in colostrum, milk, and serum of mares and foals after a healthy pregnancy. Our objective was to characterize colostrum, milk, and serum iodine levels in healthy postpartum mares and foals (n = 10) and explore relationships with thyroid hormone concentrations. Colostrum, milk, and jugular blood samples from draft breed mares and foals with an estimated average iodine daily intake of 39 mg per mare during pregnancy were obtained at Day 0 (foaling date) and/or 10 days later. Parameters studied were (1) mare basal concentrations of serum: TT3, TT4, and iodine; (2) iodine in colostrum at Day 0 and milk iodine (Day 10); and (3) foal basal: TT3, TT4, and serum iodine (Days 0 and 10). Median ± median error colostrum iodine levels (165 ± 15.1 μg/L) were higher than milk (48 ± 5.6 μg/L; P = .007) levels. Median ± median error foal serum iodine (268.5 ± 7.6 μg/L), TT4 (1,225 ± 47.8 nmol/L), and TT3 (14.2 ± 1.1 nmol/L) at foaling date were higher than at 10 days (serum iodine: 70 ± 3.6 μg/L; TT4: 69.6. ± 20.4 nmol/L; and TT3: 5.4 ± 0.3 nmol/L). In conclusion, equine mammary tissue concentrates iodine beyond plasma levels, making colostrum and milk a significant source of iodine. Foal serum iodine levels are high in the neonatal period and are positively correlated with TT4, which is important for neonatal adaptation.
Copyright © 2020 Elsevier Inc. All rights reserved.
Publication Date: 2020-04-09 PubMed ID: 32534782DOI: 10.1016/j.jevs.2020.103018Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates iodine levels in the colostrum, milk, and blood of mares and their newborn foals, exploring their relationship with thyroid hormone concentrations. It finds that colostrum and milk are significant sources of iodine, and that high iodine levels in foals are correlated with thyroid hormone levels, critical for their early development.
Study Context
- This study focuses on Iodine, thyroxine (T4) and triiodothyronine (T3) – essential elements for normal fetal growth, maturation, and the survival of newborn animals.
- Previous understanding of iodine levels in the colostrum, milk, and bloodstream of mares and foals after a healthy pregnancy was inadequate. Therefore, the researchers aimed to characterize these factors effectively.
Research Methodology
- The research examined ten healthy postpartum mares and their foals. Their average iodine intake during pregnancy was estimated at 39mg per day.
- At different instances – the day of foaling and ten days later, the research collected colostrum, milk, and jugular blood samples from the draft breed mares and foals.
- The main parameters in focus were serum, colostrum, and milk iodine levels and thyroid hormone concentrations in both mares and foals.
Key Findings
- The study found that the iodine levels in colostrum were significantly higher than in milk (165 μg/L vs. 48 μg/L).
- Furthermore, iodine, TT4, and TT3 levels in the foal’s serum were higher at birth than ten days later.
implications of the Findings
- The research concludes that the mammary tissue in mares concentrates iodine beyond plasma levels. This makes colostrum and milk significant sources of iodine, more so than previously understood.
- Furthermore, high iodine levels in foals during the early neonatal period are positively correlated with TT4 levels, which play a vital role in the adjustment of neonates to their new environment.
Conclusion
- This study has offered valuable insights into iodine levels in mares and foals postpartum, revealing critical findings about their sources and significance.
- The research can contribute to enhancing prenatal and postnatal care for mares and their foals, ensuring successful pregnancies and healthy foal development.
Cite This Article
APA
Lopez-Rodriguez MF, Cymbaluk NF, Epp T, Laarveld B, Thrasher M, Card CE.
(2020).
A Field Study of Serum, Colostrum, Milk Iodine, and Thyroid Hormone Concentrations in Postpartum Draft Mares and Foals.
J Equine Vet Sci, 90, 103018.
https://doi.org/10.1016/j.jevs.2020.103018 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
- Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
- Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
- Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
- Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
- Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Electronic address: claire.card@usask.ca.
MeSH Terms
- Animals
- Colostrum
- Female
- Horses
- Iodine
- Milk
- Postpartum Period
- Pregnancy
- Thyroid Hormones
Citations
This article has been cited 5 times.- Ellero N, Lanci A, Baldassarro VA, Alastra G, Mariella J, Cescatti M, Castagnetti C, Giardino L. Study on NGF and VEGF during the Equine Perinatal Period-Part 2: Foals Affected by Neonatal Encephalopathy. Vet Sci 2022 Aug 26;9(9).
- Ellero N, Lanci A, Baldassarro VA, Alastra G, Mariella J, Cescatti M, Giardino L, Castagnetti C. Study on NGF and VEGF during the Equine Perinatal Period-Part 1: Healthy Foals Born from Normal Pregnancy and Parturition. Vet Sci 2022 Aug 23;9(9).
- Stoeckle SD, Stage HJ, Gehlen H. Thyroid Disease in Horses-Retrospective Case Series on Patients Examined for Thyroid Disease in an Equine University Clinic (2009-2024). Vet Sci 2025 Nov 27;12(12).
- Pasolini MP, Auletta L, De Biase D, Vaccaro E, Del Prete C, Montano C, de Chiara M, Di Napoli E, Paciello O, Piegari G. Clinical and Pathological Features of Flexural Deformities Associated with Myopathies in Foals. Vet Sci 2025 Jun 6;12(6).
- Wheaton CJ, Sullivan KE, Bassiouny E, Burns CM, Smukall MJ, Hendon JM, Mylniczenko ND. Investigation of serum thyroid hormones, iodine and cobalt concentrations across common aquarium-housed elasmobranchs. Front Vet Sci 2025;12:1504527.
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