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Home / Equine Research Bank / J Vet Emerg Crit Care (San Antonio) / The effect of xylazine on intracranial pressure in anestheti...
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001)2021; 31(4); 476-482; doi: 10.1111/vec.13083

The effect of xylazine on intracranial pressure in anesthetized and standing horses.

Abstract: To determine the effect of xylazine on intracranial pressure (ICP) in standing compared to isoflurane-anesthetized horses. Methods: Prospective, crossover study design. Methods: University Teaching Hospital. Methods: Six adult horses donated to the University. Horses were determined to be healthy via physical examination, complete blood count, and neurological evaluation. Methods: Horses were anesthetized, maintained on isoflurane in oxygen in left lateral recumbency, and ventilated to normocapnia. Horses were instrumented for intraparenchymal measurement of ICP, invasive blood pressure, pulse oximetry, and end tidal gas analyzer. Xylazine 1 mg/kg was administered IV and ICP, systolic arterial pressure, mean arterial pressure (MAP), diastolic arterial pressure, and heart rate were recorded and cerebral perfusion pressure (CPP) was calculated for the following 15 minutes. Twenty-four to 36 hours following anesthetic recovery, xylazine 1 mg/kg was administered IV and ICP, heart rate, and Doppler blood pressure (BPdop) on the tail were monitored for 15 minutes. Results: There was a decrease in ICP following administration of xylazine in anesthetized horses (P < 0.003) but not standing horses (P = 0.227). There was an increase in systolic arterial pressure, MAP, diastolic arterial pressure (P < 0.001), and BPdop (P = 0.001) following administration of xylazine. As a result, CPP increased in anesthetized horses (P < 0.03). There was a negative association between ICP and MAP in anesthetized horses (P = 0.007) but not ICP and BPdop conscious horses (P = 0.379). Conclusions: Administration of xylazine to anesthetized horses resulted in an increased CPP due to decreased ICP with concurrent increased MAP. Administration of xylazine to standing horses did not result in a change in ICP. However, with the increase in BPdop found in awake horses, it is likely that CPP would also increase in awake horses following xylazine administration.
© Veterinary Emergency and Critical Care Society 2021.
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Publication Date: 2021-06-18 PubMed ID: 34143942DOI: 10.1111/vec.13083Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research studied the impact of xylazine on the intracranial pressure (ICP) in horses. The study found that xylazine decreases ICP in anesthetized horses, but not in standing horses, and that blood pressure increases after xylazine administration in both cases.

Research Methodology

  • The researchers conducted a prospective, crossover study using six adult horses in good health, as confirmed through physical exams, complete blood counts, and neurological evaluations.
  • The horses were anesthetized with isoflurane in oxygen and placed in left lateral recumbency. They were ventilated to a state of normocapnia (normal blood carbon dioxide levels).
  • In order to measure the effect of xylazine, various instruments were installed to measure ICP, invasive blood pressure, pulse oximetry (oxygen saturation level in blood), and end tidal gas volume (amount of exhaled carbon dioxide).
  • Xylazine was administered intravenously at a dose of 1 mg/kg. ICP, along with systolic arterial pressure, mean arterial pressure (MAP), diastolic arterial pressure, and heart rate, were recorded and cerebral perfusion pressure (CPP – blood flow to the brain) was calculated over the next 15 minutes.
  • The procedure was repeated after 24 to 36 hours, this time with the horses standing. ICP, heart rate, and Doppler blood pressure on the tail were monitored for 15 minutes following xylazine administration.

Research Findings

  • The research found that xylazine decreased ICP in anesthetized horses significantly (P < 0.003), but the same did not occur in standing horses (P = 0.227).
  • There was an increase in systolic arterial pressure, MAP, diastolic arterial pressure, and Doppler blood pressure after the administration of xylazine, both in anesthetized and standing horses (P < 0.001).
  • Consequently, CPP increased in anesthetized horses (P < 0.03).
  • A significant negative correlation was found between ICP and MAP in anesthetized horses (P = 0.007), but the same correlation was not found between ICP and Doppler blood pressure in standing horses (P = 0.379).

Conclusion

  • The administration of xylazine to anesthetized horses resulted in increased cerebral perfusion pressure due to decreased intracranial pressure and concurrent increase in mean arterial pressure.
  • In contrast, the administration of xylazine to standing horses did not change their intracranial pressure. However, the observed increase in Doppler blood pressure suggests that cerebral perfusion pressure would likely also increase in awake horses following the administration of xylazine.

Cite This Article

APA
Reed RA, Epstein KL, Bramski JH, Diehl KA, Ryan CA. (2021). The effect of xylazine on intracranial pressure in anesthetized and standing horses. J Vet Emerg Crit Care (San Antonio), 31(4), 476-482. https://doi.org/10.1111/vec.13083

Publication

Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001)
ISSN: 1476-4431
NlmUniqueID: 101152804
Country: United States
Language: English
Volume: 31
Issue: 4
Pages: 476-482

Researcher Affiliations

Reed, Rachel A
  • Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA.
Epstein, Kira L
  • Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA.
Bramski, Jessica H
  • Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA.
Diehl, Kathryn A
  • Department of Small Animal Medicine and Surgery, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA.
Ryan, Clare A
  • Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA.

MeSH Terms

  • Animals
  • Blood Pressure
  • Cross-Over Studies
  • Heart Rate
  • Horses
  • Intracranial Pressure
  • Isoflurane
  • Prospective Studies
  • Xylazine / pharmacology

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