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veterinary
farriery
2020
Cohort Study

Reference values for 2-dimensional and M-mode echocardiography in Friesian and Warmblood horses.

Authors: Vernemmen Ingrid, Vera Lisse, Van Steenkiste Glenn, van Loon Gunther, Decloedt Annelies

Journal: Journal of veterinary internal medicine

Summary

# Editorial Summary: Echocardiographic Reference Values in Friesian and Warmblood Horses Until now, veterinary clinicians have lacked breed-specific echocardiographic reference ranges for Friesians, relying instead on generalised standards that may not account for breed-specific cardiac anatomy. Vernemmen and colleagues conducted a cross-sectional study of 100 healthy adult Friesians and 100 healthy adult Warmbloods, obtaining comprehensive 2D and M-mode echocardiographic measurements of cardiac chamber dimensions, areas, and volumes using standardised techniques including the modified Simpson's method. The findings revealed several clinically significant differences: Friesian horses demonstrated substantially smaller left ventricular end-diastolic volumes (95–245 mL smaller than Warmbloods), reduced right ventricular dimensions (internal diameters approximately 0.6–1.5 mm smaller), but paradoxically higher fractional shortening and ejection fraction values, suggesting more efficient systolic function relative to chamber size. No evidence of secondary cardiac changes—such as concentric hypertrophy—were observed, ruling out compensatory remodelling from systemic hypertension. For equine practitioners, these breed-specific reference intervals are essential for accurate cardiac assessment in Friesians; applying Warmblood standards to this breed risks misinterpretation of normal anatomy as pathological, potentially leading to unnecessary intervention or conversely, missed detection of genuinely abnormal findings.

Read the full abstract on PubMed

Practical Takeaways

  • Friesian horses have inherently smaller cardiac dimensions than Warmbloods—use breed-specific reference values when interpreting echocardiograms to avoid misclassifying normal variation as pathology
  • When examining Friesian horses echocardiographically, expect smaller left and right ventricular measurements and higher functional indices compared to Warmblood-based reference ranges
  • This study provides clinically applicable reference intervals specific to Friesians, improving diagnostic accuracy in equine cardiac assessments for this breed

Key Findings

  • Friesians have significantly smaller left ventricular end-diastolic volumes compared to Warmbloods (difference: -245 to -63 mL)
  • Right ventricular end-diastolic and peak-systolic diameters are smaller in Friesians (differences: -1.33 to -0.6 mm and -1.54 to -0.76 mm respectively)
  • Friesians demonstrate significantly larger fractional shortening and ejection fraction compared to Warmbloods (differences: 0.61-6% and 0.21-4.6% respectively)
  • Breed-specific reference intervals for echocardiographic measurements are necessary, as standard reference ranges do not account for breed-related cardiac size differences

Conditions Studied

healthy horses (reference population)