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  • Author or Editor: Peyton A. Jones x
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To evaluate the oncotic, hemodilutional, and hemostatic effects of IV infusions of a large volume of isotonic saline solution and 2 doses of 6% hydroxyethyl starch (HES) in clinically normal ponies.


12 adult ponies.


Ponies were assigned to 3 treatment groups and received the following IV infusions: 80 ml of 0.9% sodium chloride/kg; 10 ml of 6% HES (in 0.9% sodium chloride)/kg; or 20 ml of 6% HES (in 0.9% sodium chloride)/kg. Blood samples were collected for determination of colloid oncotic pressure (COP), PCV, plasma total protein concentration, platelet count, von Willebrand factor antigen (vWf:Ag) activity, fibrinogen concentration, prothrombin time, activated partial thromboplastin time (APTT), and factor VIII coagulant (FVIII:C) activity. A rocket immunoelectrophoretic procedure was used for determination of vWf:Ag activity. A modification of the APTT assay was used for determination of FVIII:C activity. Cutaneous bleeding time was determined, using a template method.


Mean COP was persistently increased over baseline values in the face of hemodilution in HES-treated ponies. Prothrombin time, APTT, and fibrinogen concentrations decreased after infusions and vWf:Ag and FVIII:C activities were decreased in dosedependent manner in HES-treated ponies. Though cutaneous bleeding time was not significantly affected in ponies of any group, a trend toward prolongation of bleeding time was evident in ponies receiving 20 ml of HES/kg. This trend appeared to be associated with marked decrement in vWf:Ag activity at this dosage.

Conclusions and Clinical Relevance

Infusion of HES in clinically normal ponies increases COP, and exerts dose-dependent hemodilutional effects and dose-dependent effects on specific hemostatic variables. Thus, HES may be useful for resuscitative fluid treatment of horses. (Am J Vet Res 1997;58:541–548)

Free access
in American Journal of Veterinary Research


Objective—To determine the effect of hydroxyethyl starch (HES) on colloid oncotic pressure (π) during fluid resuscitation of hypoproteinemic horses and to evaluate the clinical usefulness of direct and indirect methods for determination of π before and after infusion of a synthetic colloid.

Design—Prospective clinical study.

Animals—11 hypoproteinemic horses.

Procedure—Horses received IV infusions of 8 to 10 ml of a 6% solution of HES/kg (3.6 to 4.5 ml/lb) of body weight during fluid resuscitation. Blood samples were obtained for determination of plasma measured colloid oncotic pressure (πmeas) and plasma total protein and albumin (A) concentrations. Plasma globulin concentration (G) was calculated as the difference between plasma total protein and albumin concentrations. Calculated values for colloid oncotic pressure (πA + G) were determined by use of a predictive nomogram previously developed for horses.

Results—There was no significant difference between the means of πmeas and πA + G at the beginning of HES infusion. After HES infusion, the mean of πmeas was increased significantly from baseline for 6 hours. Mean plasma total protein and albumin concentrations and πA + G were decreased significantly from baseline for 24 hours. Differences between mean πmeas and πA + G after HES infusion were significant for 24 hours.

Conclusions and Clinical Relevance—There was good agreement between plasma πmeas and πA + G in blood samples obtained from hypoproteinemic horses immediately before infusion of HES. Use of a predictive nomogram did not, however, account for the oncotic effect of HES. Results of comparison of πmeas to πA + G after HES infusion suggest that a significant oncotic effect was maintained for 24 hours in the study horses. (J Am Vet Med Assoc 2001;218: 1130–1135)

Full access
in Journal of the American Veterinary Medical Association