Plasma colloid osmotic pressure and total protein in horses during colic surgery

Pedro Boscan, Eugene Steffey

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


To assess the changes in colloid osmotic pressure (COP) in horses undergoing surgery for colic. Prospective clinical evaluation. Twenty-nine adult horses presented for emergency laparotomy. Horses were premedicated with intravenous (IV) xylazine and anesthesia was induced with ketamine, diazepam and guaifenesin and was maintained with isoflurane as required. Lactated Ringer's solution (LRS) was given to all horses during anesthesia. Blood was collected in heparin before, and every 30 minutes during, anesthesia to measure COP, total protein concentration (TP), osmolality, packed cell volume, electrolytes, glucose and lactate. In addition, COP was estimated using different formulas previously described for horses. Before anesthesia, COP and TP were 18.7 ± 2.2 mmHg (2.49 ± 0.29 kPa) and 6.3 ± 0.7 g dL -1, respectively. The horses received a mean ± SD of 19.5 ± 3.9 mL kg-1 hour-1 (range 15-25 mL kg -1hour-1) of LRS during anesthesia. The COP and TP decreased linearly (R2 = 0.99, p < 0.01) during anesthesia and reached the lowest point at the end of anesthesia with a COP of 11.6 ± 1.6 mmHg (1.55 ± 0.21 kPa) and TP of 4.4 ± 0.4 g dL-1. The Pearson correlation coefficient for COP versus TP was r2 = 0.78. Calculation of COP from TP concentrations showed that two formulas could predict COP to within 1 mmHg (0.13 kPa) (Thomas & Brown 1992; Boscan et al. 2007). Colloid osmotic pressure, like TP, decreased greatly over the course of crystalloid fluid infusion during anesthesia for laparotomy in horses with colic. This change may predispose the animal to tissue edema with subsequent morbidity.

Original languageEnglish (US)
Pages (from-to)408-415
Number of pages8
JournalVeterinary Anaesthesia and Analgesia
Issue number6
StatePublished - Jan 1 2007


  • Anesthesia
  • Crystalloids
  • Equine
  • Laparotomy
  • Oncotic pressure

ASJC Scopus subject areas

  • veterinary(all)


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