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Effects of head position on internal and external carotid pressures in standing sedated horses

Stacy R Caffey1, Caleb M Lund1, Kelly D Farnsworth1

  • 1Department of Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164-6610, USA.

Canadian Journal of Veterinary Research = Revue Canadienne De Recherche Veterinaire
|April 22, 2021
PubMed

Insights

Head position significantly impacts equine arterial pressures. A head-up posture reduces mean arterial pressure in the internal carotid artery (ICA) and external carotid artery (ECA) compared to a head-down position.

Area of Science:

  • Veterinary Medicine
  • Equine Physiology
  • Cardiovascular Research

Background:

  • Accurate measurement of arterial pressures in horses is crucial for diagnosing and managing various conditions.
  • Understanding physiological responses to positional changes is important for interpreting hemodynamic data.

Purpose of the Study:

  • To investigate the effect of head position (head-up vs. head-down) on internal carotid artery (ICA) and external carotid artery (ECA) pressures in standing sedated horses.
  • To determine if head position influences mean arterial pressure (MAP) in these specific arteries.

Main Methods:

  • Six standing sedated horses were included in the study.
  • Ultrasound-guided catheterization of the common carotid artery (CCA) allowed for pressure transducer placement in the ICA and ECA.
  • Endoscopic visualization confirmed transducer placement at the guttural pouch level.
  • Mean arterial pressure (MAP) was recorded in both head-up and head-down positions.
  • The dorsal metatarsal artery was catheterized as a control site.

Main Results:

  • A head-up position significantly decreased MAP in both the ICA (median: 75.21 mmHg) and ECA (median: 79.43 mmHg) compared to the head-down position (ICA median: 104.65 mmHg; ECA median: 102.26 mmHg).
  • MAP in the dorsal metatarsal artery, used as a control, was not affected by head position.
  • The observed decrease in ICA and ECA pressures in the head-up position was statistically significant (P = 0.03).

Conclusions:

  • Head position is a critical factor influencing arterial blood pressure measurements in the equine ICA and ECA.
  • Clinical interpretation of ICA and ECA pressures in standing sedated horses must account for the animal's head position.
  • Further research may explore the mechanisms behind these positional pressure changes in horses.

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