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Home / Equine Research Bank / Equine Vet J / Mono-dimensional, two-dimensional and Doppler echocardiograp...
Equine veterinary journal2026; doi: 10.1002/evj.70140

Mono-dimensional, two-dimensional and Doppler echocardiographic measurements in healthy Standardbred neonatal foals in the first 5 days of life.

Abstract: Bodyweight, age and breed influence the echocardiographic assessment of foals. There are no echocardiographic studies in Standardbred neonatal foals. Objective: To describe echocardiographic values for selected variables, evaluate intra- and inter-observer variability and assess cardiac changes in the first 5 days of life in healthy Standardbred neonatal foals. Methods: Prospective observational study. Methods: Fifty-six healthy Standardbred neonatal foals were examined by transthoracic echocardiography using standard right parasternal and subcostal views at three time points: in the first 48 h (T1), between 49 and 96 h (T2), and 97 and 144 h (T3) after birth. Descriptive statistics, variability analysis and linear mixed models assessed age-related changes in cardiac parameters. Intra/inter-observer variability was assessed using intraclass correlation coefficients (ICC). Results: A total of 114 echocardiographic examinations were performed. Intra-observer agreement was excellent for most variables, while inter-observer agreement was excellent in approximately half. An increase in end-diastolic left ventricular internal diameter (T1: 5.3 ± 0.6 cm; T3: 5.6 ± 0.8 cm; p < 0.01), left atrial diameter in the four-chamber view (T1: 5.8 ± 0.6 cm; T3: 6.0 ± 0.6 cm; p = 0.01), end-diastolic aortic sinus diameter in the left ventricular outflow tract view (T1: 3.0 ± 0.3 cm; T3: 3.2 ± 0.3 cm; p < 0.01) and peak velocity of the transmitral E wave (T1: 0.8 ± 0.1 m/s; T3: 0.9 ± 0.1 m/s; p < 0.01) were observed over time. Additionally, a gradual decrease in the end-diastolic pulmonary diameter at the sinus (T1: 2.8 ± 0.3 cm; T3: 2.5 ± 0.3 cm; p < 0.01) and at the valve (T1: 2.6 ± 0.3 cm; T3: 2.5 ± 0.4 cm; p = 0.03) levels was noted. Conclusions: Some variables have fewer individuals; coefficients of variation are moderate to high for some variables. Conclusions: Changes in echocardiographic variables in a healthy Standardbred neonatal foal population reflect a physiological adaptation of the cardiorespiratory system from foetal to extrauterine life. These observations can be used as a reference in the assessment of neonatal foals of similar age and weight.
© 2026 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2026-01-06 PubMed ID: 41493062DOI: 10.1002/evj.70140Google Scholar: Lookup
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Summary

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Overview

  • This study establishes normal heart ultrasound (echocardiographic) measurements in healthy newborn Standardbred foals during their first five days of life.
  • It evaluates how heart measurements change in the initial days after birth and examines the reliability of these measurements when taken by the same or different observers.

Background and Objective

  • Bodyweight, age, and breed are known to affect heart ultrasound assessments in foals.
  • Prior to this study, no echocardiographic data existed specifically for Standardbred neonatal foals, which is a common horse breed.
  • The study aimed to:
    • Describe typical heart ultrasound values for certain heart measurements in these foals.
    • Assess how consistent these measurements are when repeated by the same observer (intra-observer variability) and different observers (inter-observer variability).
    • Identify how these heart measurements change physiologically during the first 5 days after birth.

Methods

  • Study design: Prospective observational study involving 56 healthy Standardbred neonatal foals.
  • The foals underwent transthoracic echocardiographic exams at three time periods after birth:
    • T1: Within the first 48 hours
    • T2: Between 49 and 96 hours
    • T3: Between 97 and 144 hours
  • Echocardiograms used standard right parasternal and subcostal imaging views to capture heart structures and blood flow.
  • Statistical analyses included descriptive statistics, variability analyses, and linear mixed models to detect age-related heart parameter changes.
  • Reliability of measurements was assessed using intraclass correlation coefficients (ICC) for both intra- and inter-observer variability.

Key Results

  • A total of 114 echocardiographic exams were performed across the foal cohort.
  • Intra-observer variability (the same person repeating measurements) showed excellent agreement for most heart variables, indicating high measurement consistency.
  • Inter-observer variability (different people making measurements) showed excellent agreement about half the time, reflecting some variability depending on the measurer.
  • Significant changes in heart measurements were observed over the 5-day period, including:
    • Increase in end-diastolic left ventricular internal diameter (from 5.3 cm to 5.6 cm).
    • Increase in left atrial diameter measured in the four-chamber heart view (from 5.8 cm to 6.0 cm).
    • Increase in end-diastolic aortic sinus diameter observed in the left ventricular outflow tract view (from 3.0 cm to 3.2 cm).
    • Increase in peak velocity of the transmitral E wave, indicating changes in blood flow speed during heart filling (from 0.8 m/s to 0.9 m/s).
    • Decrease in the pulmonary artery diameter at both the sinus and valve levels (from 2.8 cm to 2.5 cm and from 2.6 cm to 2.5 cm respectively).
  • Some measurements had fewer foals contributing data, and there was moderate to high variability (coefficient of variation) in some variables.

Conclusions and Implications

  • The observed changes in heart size and blood flow parameters reflect normal physiological adaptations as the foal’s cardiovascular and respiratory systems transition from fetal to postnatal life.
  • The values and trends documented can serve as reference standards for veterinarians assessing healthy Standardbred foals at a similar age and bodyweight.
  • The study highlights the importance of using consistent measurement techniques to reduce observer variability in echocardiographic assessments.
  • These findings improve understanding of normal cardiac development in neonatal Standardbred foals, assisting in the early detection of cardiac abnormalities in this breed.

Cite This Article

APA
D'el Rey Dantas FT, Forni G, Hallowell G, Castagnetti C, Menchetti L, Romito G, Lanci A, Mariella J, Freccero F. (2026). Mono-dimensional, two-dimensional and Doppler echocardiographic measurements in healthy Standardbred neonatal foals in the first 5 days of life. Equine Vet J. https://doi.org/10.1002/evj.70140

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

D'el Rey Dantas, Fernanda Timbó
  • Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
Forni, Giulia
  • Department of Animal Medicine, Production and Health, University of Padova, Padova, Italy.
Hallowell, Gayle
  • Medicine Vet Equine Referrals, Leicestershire, UK.
Castagnetti, Carolina
  • Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
Menchetti, Laura
  • School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy.
Romito, Giovanni
  • Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
Lanci, Aliai
  • Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
Mariella, Jole
  • Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
Freccero, Francesca
  • Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.

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