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Home / Equine Research Bank / Can Vet J / A case-control study of the congenital hypothyroidism and dy...
The Canadian veterinary journal = La revue veterinaire canadienne1996; 37(6); 349-358;

A case-control study of the congenital hypothyroidism and dysmaturity syndrome of foals.

Abstract: A case-control study was conducted to identify risk factors for the congenital hypothyroidism and dysmaturity syndrome of foals. A questionnaire was used during personal interviews of foal owners and farm managers to collect information on animal signalment, farm environment, and mare management. Information on 39 foals with the congenital hypothyroidism and dysmaturity syndrome were compared with 39 control foals. Foals with the syndrome had a significantly (P < 0.0001) longer gestation (357.6 d) than control foals (338.9 d). Pregnant mares that were fed greenfeed, did not receive any supplemental mineral, left their "home farm" during gestation, or grazed irrigated pasture had 13.1 (P = 0.0068), 5.6 (P = 0.0472), 4.3 (P = 0.0076), and approximately 15.3 (P = 0.0245), respectively, greater odds of producing an affected foal than mares not experiencing these events. Greenfeed often contains high levels of nitrate (NO3-), which is known to impair thyroid gland function. In light of this, forage samples from participating farms were analyzed for nitrate levels. The odds of one or more congenitally hypothyroid and dysmature foals being born on a farm feeding forage with at least a trace of nitrate was 8.0 times greater (P = 0.0873) than the odds of the disease occurring on a farm that fed forage free of nitrate. Further, the odds of a mare producing an affected foal when fed forage containing at least a trace of nitrate were 5.9 times greater (P = 0.0007) than those of a mare fed nitrate free forage. This study suggests that congenital hypothyroidism and dysmaturity syndrome in foals may be the result of diets that contain nitrate or that are low in iodine being fed to pregnant mares.
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Publication Date: 1996-06-01 PubMed ID: 8689594PubMed Central: PMC1576403
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigates the risk factors associated with congenital hypothyroidism and dysmaturity syndrome in foals, suggesting a link between diets heavy in nitrate or low in iodine for pregnant mares and the likelihood of producing foals with these conditions.

Study Methodology

  • The research employed a case-control approach to identify potential risk factors contributing to congenital hypothyroidism and dysmaturity syndrome among newborn horses.
  • Data was gathered through personal interviews with foal owners and farm managers, using a questionnaire to collect information on the animal, the farm environment and the management of pregnant mares.
  • The responses pertaining to 39 foals diagnosed with the syndrome were compared to those relating to 39 healthy control foals.

Key Findings

  • The study found that foals with the syndrome had a noticeably longer gestation period compared to the control foals.
  • Mares that were fed greenfeed, did not receive supplemental minerals, moved away from their “home farm” during pregnancy, or grazed on irrigated pasture had significantly higher odds of producing a foal with the syndrome.
  • Nitrate in greenfeed can impair thyroid gland function, prompting the researchers to analyze nitrate levels in the forage provided at each farm.
  • Farms that fed their horses forage containing at least trace amounts of nitrate were more likely to have foals born with congenital hypothyroidism and dysmaturity syndrome. Similarly, mares fed with nitrate-containing forage had higher chances of producing affected foals.

Study Conclusion

  • The research suggests that certain diets for pregnant mares, notably those containing nitrate or low in iodine, might increase the risk of congenital hypothyroidism and dysmaturity syndrome in foals.
  • This provides valuable insights for mare management to prevent such conditions and warrants further investigation for more definitive conclusions and specific dietary guidelines.

Cite This Article

APA
Allen AL, Townsend HG, Doige CE, Fretz PB. (1996). A case-control study of the congenital hypothyroidism and dysmaturity syndrome of foals. Can Vet J, 37(6), 349-358.

Publication

The Canadian veterinary journal = La revue veterinaire canadienne
ISSN: 0008-5286
NlmUniqueID: 0004653
Country: Canada
Language: English
Volume: 37
Issue: 6
Pages: 349-358

Researcher Affiliations

Allen, A L
  • Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon.
Townsend, H G
    Doige, C E
      Fretz, P B

        MeSH Terms

        • Animal Feed
        • Animals
        • Animals, Newborn
        • Case-Control Studies
        • Congenital Hypothyroidism
        • Gestational Age
        • Horse Diseases / epidemiology
        • Horses
        • Hypothyroidism / epidemiology
        • Hypothyroidism / veterinary
        • Musculoskeletal Abnormalities
        • Nitrates / administration & dosage
        • Risk Factors
        • Surveys and Questionnaires
        • Syndrome

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        Citations

        This article has been cited 7 times.
        1. 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.
          pubmed: 38562984
        2. Ibrahim RS, El-Mezayen NS, Khairy A, Zaatout HH, Hammoda HM, Metwally AM. Biologically-Guided Isolation of Natural Lead Antithyroid Drug from Medicago sativa L. Sprouts and Its Toxic Profile in Comparison with Propylthiouracil. J Food Drug Anal 2020 Sep 15;28(3):407-448.
          doi: 10.38212/2224-6614.1242pubmed: 35696097google scholar: lookup
        3. Rogers CW, Bolwell CF, Gee EK. Proactive Management of the Equine Athlete. Animals (Basel) 2012 Dec 19;2(4):640-55.
          doi: 10.3390/ani2040640pubmed: 26487168google scholar: lookup
        4. Swerczek TW. Tyzzer's disease in foals: retrospective studies from 1969 to 2010. Can Vet J 2013 Sep;54(9):876-80.
          pubmed: 24155494
        5. Edwards TM, Miller HD, Guillette LJ Jr. Water quality influences reproduction in female mosquitofish (Gambusia holbrooki) from eight Florida springs. Environ Health Perspect 2006 Apr;114 Suppl 1(Suppl 1):69-75.
          doi: 10.1289/ehp.8056pubmed: 16818249google scholar: lookup
        6. Gawrylash SK. Thyroid hyperplasia and musculoskeletal deformity in a standardbred filly in Ontario. Can Vet J 2004 May;45(5):424-6.
          pubmed: 15206593
        7. Allen A. Congenital hypothyroidism in foals. Can Vet J 2001 Jun;42(6):418.
          pubmed: 11424573
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