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Equine veterinary journal2020; 52(6); 876-883; doi: 10.1111/evj.13267

Normal regression of the internal umbilical remnant structures in Standardbred foals.

Abstract: Diseases affecting the internal umbilical remnant are common in foals. Ultrasound is used to diagnose abnormalities of these structures, and to monitor treatment. However, little is known about the progression of normal internal umbilical remnant regression. Objective: To document normal regression of the umbilical remnant in foals over the first 6 weeks of life. Methods: Prospective, longitudinal cohort study. Methods: Weekly ultrasound examinations were performed beginning at 1 day of age in 34 healthy Standardbred foals. The umbilical vein was measured in cross section just cranial to the external umbilicus, at the level of the liver and midway between these points. The umbilical arteries were measured in cross section just caudal to the external umbilicus, at the apex of the bladder and at the midpoint of the bladder. The urachus was imaged longitudinally as it exited the bladder. Reduction in size over time was evaluated as percentage change in diameter. Results: Structure diameter decreased linearly over time. The largest measurements were at 24 hours of age with a median umbilical vein diameter of 0.83 cm (IQR 0.77-1.02 cm), median umbilical artery diameter of 0.61 cm (IQR 0.56-0.70 cm) and median urachal diameter of 1.07 cm (IQR 1.02-1.14 cm). There was a significant reduction in diameter for all structures (16.0%-21.9%; corrected P < .001) within the first week of life. Conclusions: All foals were of a single breed, and examinations and measurements were performed by multiple individuals. Conclusions: The internal umbilical remnants (umbilical vein/arteries, and urachus) rapidly regress over the first few weeks of life. The median internal umbilical remnant diameters reported here are smaller than previously reported values, emphasising the importance of accounting for age when diagnosing umbilical abnormalities. In a healthy Standardbred foal, normal structures are difficult to definitively identify via transcutaneous ultrasound by 5-6 weeks of age.
Publication Date: 2020-04-30 PubMed ID: 32289179DOI: 10.1111/evj.13267Google Scholar: Lookup
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  • Journal Article

Summary

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This study investigates the natural regression of the internal umbilical remnant in Standardbred foals over the first six weeks of life. The findings reveal a rapid regression in umbilical remnants (umbilical vein/arteries, and urachus) during this period, emphasizing the need to consider the foal’s age when diagnosing umbilical abnormalities.

Study Details

  • The focus of the research was on internal umbilical remnant diseases that are common in foals.
  • were identified and measured weekly from the first day of birth until six weeks of age.
  • The research was performed as a prospective, longitudinal cohort study involving 34 healthy Standardbred foals.
  • Diagnostic ultrasound was the tool used to detect and monitor any abnormalities within these structures.

Methodology

  • The researchers performed weekly ultrasound examinations.
  • The umbilical vein was measured in three areas: just cranial to the external umbilicus, at the level of the liver, and midway between.
  • The umbilical arteries were also measured in three areas: just caudal to the external umbilicus, at the apex of the bladder, and at the midpoint of the bladder.
  • The urachus was imaged longitudinally as it exited the bladder.
  • The reduction in size over time was evaluated based on the percentage change in diameter.

Results

  • There was noted to be a linear decrease in structure diameter over time. The largest measurements were recorded at 24 hours of age.
  • Within the first week of life, all structures showed a significant reduction in diameter ranging from 16.0% to 21.9%.
  • These findings are smaller than previous reported values for these structures, indicating a possible overlooked factor of age in prior diagnoses and studies.

Conclusions

  • All foals included in the study were of a single breed and examinations were conducted by multiple individuals, which adds a level of variability in data collection.
  • By 5-6 weeks of age, it was challenging to definitively identify the normal structures of a healthy Standardbred foal via transcutaneous ultrasound.
  • This rapid regression of the internal umbilical remnants process emphasizes the significance of age consideration when diagnosing umbilical abnormalities.

Cite This Article

APA
McCoy AM, Lopp CT, Kooy S, Migliorisi AC, Austin SM, Wilkins PA. (2020). Normal regression of the internal umbilical remnant structures in Standardbred foals. Equine Vet J, 52(6), 876-883. https://doi.org/10.1111/evj.13267

Publication

ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 52
Issue: 6
Pages: 876-883

Researcher Affiliations

McCoy, Annette M
  • Department of Veterinary Clinical Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA.
Lopp, Christine T
  • Department of Veterinary Clinical Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA.
Kooy, Sarah
  • Department of Veterinary Clinical Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA.
Migliorisi, Alessandro C
  • Department of Veterinary Clinical Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA.
Austin, Scott M
  • Department of Veterinary Clinical Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA.
Wilkins, Pamela A
  • Department of Veterinary Clinical Medicine, University of Illinois Urbana-Champaign, Urbana, IL, USA.

MeSH Terms

  • Animals
  • Horses
  • Longitudinal Studies
  • Prospective Studies
  • Umbilical Veins
  • Umbilicus / diagnostic imaging
  • Urachus

Grant Funding

  • University of Illinois Companion Animal Research Funds

References

This article includes 12 references
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Citations

This article has been cited 4 times.
  1. Vitale V, Nocera I, Sgorbini M, Aliboni B, Laus F, Mannini A, Bazzano M. Ultrasonography Evaluation of Umbilical Structures in Clinically Healthy Donkey Foals during the First Week of Life. Animals (Basel) 2021 Jun 2;11(6).
    doi: 10.3390/ani11061650pubmed: 34199350google scholar: lookup
  2. Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
    doi: 10.1111/avj.70003pubmed: 40903020google scholar: lookup
  3. Saitua A, Sanchez de Medina A, Bulnes F, Buzon A, Miraz R, Argüelles D, Diez de Castro E. Urogenital surgery in foals. Front Vet Sci 2025;12:1520491.
    doi: 10.3389/fvets.2025.1520491pubmed: 40586037google scholar: lookup
  4. Buzon-Cuevas A, Duaso J, Sanchez de Medina A, Sierra JM, Perez-Ecija A, Mendoza FJ. Description of a Modified Two-Step Omphalectomy Technique Using the LigaSure(™) Device to Remove the Whole Extrahepatic Umbilical Vein: A Case Series Study in Equine and Donkey Foals. Animals (Basel) 2025 Mar 28;15(7).
    doi: 10.3390/ani15070981pubmed: 40218374google scholar: lookup