Oncotic, hemodilutional, and hemostatic effects of isotonic saline and hydroxyethyl starch solutions in clinically normal ponies.
OBJECTIVE
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.


METHODS
12 adult ponies.


METHODS
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.


RESULTS
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 dose-dependent 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
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.
Jones
P A
PA
Department of Clinical Studies, School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square 19348-1692, USA.
Tomasic
M
M
Gentry
P A
PA
D000818:Animals; D001798:Blood Proteins / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005169:Factor VIII / Q000032:analysis; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D006438:Hemodilution / Q000662:veterinary; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006487:Hemostasis / Q000187:drug effects* / Q000502:physiology; D006736:Horses / Q000097:blood / Q000502:physiology*; D006895:Hydroxyethyl Starch Derivatives / Q000008:administration & dosage / Q000494:pharmacology*; D007262:Infusions, Intravenous / Q000662:veterinary; D007552:Isotonic Solutions; D008297:Male; D010314:Partial Thromboplastin Time; D010976:Platelet Count / Q000187:drug effects; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D014841:von Willebrand Factor / Q000032:analysis
D001798:Blood Proteins; D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D014841:von Willebrand Factor; D012965:Sodium Chloride; D005169:Factor VIII; D005340:Fibrinogen