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Home / Equine Research Bank / Animals (Basel) / Ultrasonographic Assessment of Caudal Vena Cava Collapsibili...
Animals : an open access journal from MDPI2025; 15(19); 2837; doi: 10.3390/ani15192837

Ultrasonographic Assessment of Caudal Vena Cava Collapsibility Index, Caudal Vena Cava-to-Aorta, and Femoral Vein-to-Artery Ratios in Healthy Sedated Adult Horses.

Abstract: (1) Background: Ultrasonography of major vessels helps evaluate fluid status and responsiveness in critical human and canine patients. Aims: transrectal and inguinal ultrasonography of caudal vena cava (CVC), aorta (Ao), and femoral artery (FA) and vein (FV) in horses; calculate CVC collapsibility index (CI CVC) and vein-to-artery ratios; compare B- and M-mode; and evaluate repeatability and reproducibility. (2) Methods: B-mode and M-mode video loops were recorded twice by transrectal (Ao, CVC) and inguinal ultrasonography (FV, FA) by two operators on 17 healthy, sedated adult horses. Diameters and areas were measured. CI CVC, CVC-to-Ao ratio (CVC/Ao), FV-to-FA ratio (FV/FA), reproducibility, and repeatability were calculated. (3) Results: Vessels were successfully visualized (mean time: rectal 4 min, inguinal 3 min). CVC displayed respiratory-related dimension changes. Ratios included CI CVC (mean diameter B-mode 30 ± 13%, M-mode 33 ± 12%; area 36 ± 15%), CVC/Ao (mean diameter B-mode 0.43 ± 0.15, M-mode 0.43 ± 0.11; median area 0.56, IQR 0.53-0.64), and FV/FA (mean diameter 3.80 ± 1.02; median area 26.74, IQR 25.23-32.40). M-mode was inadequate for inguinal analysis. B-mode and M-mode measurements did not differ significantly. Repeatability and reproducibility were excellent (transrectal ratios 93.9% and 94.4%, respectively); FV/FA 96.9%. (4) Conclusions: Assessment of CI CVC, CVC/Ao, and FV/FA is feasible, highly repeatable, and reproducible.
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Publication Date: 2025-09-28 PubMed ID: 41096432PubMed Central: PMC12523397DOI: 10.3390/ani15192837Google Scholar: Lookup
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Summary

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Overview

  • This study evaluated the use of ultrasonography to measure specific vessel dimensions and ratios in healthy sedated adult horses, aiming to assess fluid status and vascular parameters using various ultrasound modes and approaches.
  • The research focused on the caudal vena cava, aorta, femoral vein, and femoral artery, calculating collapsibility and vein-to-artery ratios, and assessing the repeatability and reproducibility of these measurements.

Background and Aims

  • In human and canine critical care, ultrasonography of major blood vessels is commonly used to evaluate fluid status and fluid responsiveness.
  • Such techniques had not been extensively studied in horses, hence this research aimed to extend these assessments to equine patients using ultrasonographic methods.
  • Specific objectives included:
    • Using transrectal ultrasonography to visualize and measure the caudal vena cava (CVC) and aorta (Ao).
    • Using inguinal ultrasonography for evaluating the femoral vein (FV) and femoral artery (FA).
    • Calculating the caudal vena cava collapsibility index (CI CVC), CVC-to-aorta ratio (CVC/Ao), and femoral vein-to-artery ratio (FV/FA).
    • Comparing measurements obtained using two ultrasound modes: B-mode (brightness mode) and M-mode (motion mode).
    • Evaluating the repeatability (consistency of measurements by the same operator) and reproducibility (consistency between different operators) of measurements.

Methods

  • Seventeen healthy adult horses were sedated to facilitate ultrasonographic examination.
  • Two operators independently performed imaging twice on each horse to ensure data robustness.
  • Transrectal ultrasonography targeted the aorta and caudal vena cava, while inguinal ultrasonography visualized the femoral vein and artery.
  • B-mode and M-mode video loops were recorded for each vessel, allowing diameter and cross-sectional area measurements.
  • Data collected included respiratory-dependent variations in vessel size, used for calculating the CI CVC and ratio metrics.
  • Statistical analyses assessed:
    • Differences between B-mode and M-mode measurements.
    • Repeatability within the same operator sessions.
    • Reproducibility between the two operators.

Results

  • Visualization of the targeted vessels was successful in all individuals with a mean time of 4 minutes for the transrectal approach and 3 minutes for the inguinal approach.
  • The caudal vena cava showed dimension changes corresponding to respiratory cycles, confirming dynamic collapsibility behavior.
  • Measured ratios:
    • CI CVC: mean collapsibility index of approximately 30-33% in diameter using both B-mode and M-mode; area collapsibility averaged around 36%.
    • CVC/Ao ratio: mean diameter ratio about 0.43; area ratio median around 0.56.
    • FV/FA ratio: mean diameter ratio approximately 3.8; area ratio median about 26.7.
  • M-mode was found to be inadequate for evaluating vessels during inguinal ultrasonography, indicating limitations based on anatomical location or vessel accessibility.
  • There were no significant differences between measurements obtained by B-mode and M-mode for applicable vessels.
  • Repeatability and reproducibility for the transrectal vessel ratios were excellent, exceeding 93%, and FV/FA ratio assessments showed even higher consistency at 96.9%.

Conclusions

  • This study demonstrated that ultrasonographic assessment of the CI CVC, CVC/Ao ratio, and FV/FA ratio is feasible in healthy sedated adult horses.
  • The techniques were shown to be highly repeatable and reproducible, making them reliable for potential clinical or research applications.
  • B-mode ultrasonography was preferred for inguinal evaluations due to limitations identified with M-mode in this area.
  • These vessel metrics could potentially be used to monitor fluid status or cardiovascular health in horses, analogous to approaches used in human and canine medicine.

Cite This Article

APA
Scala E, Durie I, Gommeren K, Saegerman C, van Galen G. (2025). Ultrasonographic Assessment of Caudal Vena Cava Collapsibility Index, Caudal Vena Cava-to-Aorta, and Femoral Vein-to-Artery Ratios in Healthy Sedated Adult Horses. Animals (Basel), 15(19), 2837. https://doi.org/10.3390/ani15192837

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 15
Issue: 19
PII: 2837

Researcher Affiliations

Scala, Elisa
  • Evidensia Strömsholm Referral Equine Hospital, 734 94 Strömsholm, Sweden.
Durie, Inge
  • Evidensia Strömsholm Referral Equine Hospital, 734 94 Strömsholm, Sweden.
Gommeren, Kris
  • Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Liege, 4000 Liege, Belgium.
Saegerman, Claude
  • Department of Infections and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liege, 4000 Liege, Belgium.
van Galen, Gaby
  • Sydney School of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia.
  • Goulburn Valley Equine Hospital, Congupna, VIC 3633, Australia.

Grant Funding

  • IVC Evidensia
  • Stiftelsen Strömsholm Djursjukvård

Conflict of Interest Statement

Elisa Scala and Inge Durie are affiliated with Evidensia Strömsholm Referral Equine Hospital, and Gaby van Galen is affiliated with Goulburn Valley Equine Hospital. This study was supported by funding from IVC Evidensia and Stiftelsen Strömsholm Djursjukvård. The other authors have no competing interests.

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