A comparison of the effects of a 4% modified fluid gelatin and a 6% hydroxyethyl starch on haemodilution, colloid osmotic pressure, haemostasis and renal parameters in healthy ponies.
Authors: Gratwick Z, Viljoen A, Page P C, Goddard A, Fosgate G T, Lyle C H
Journal: Equine veterinary journal
Summary
# Editorial Summary Concerns about hydroxyethyl starch (HES) causing renal dysfunction and coagulation abnormalities in human medicine have prompted investigation into safer alternatives for equine fluid therapy. Gratwick and colleagues conducted a randomised crossover trial in six healthy ponies, administering three treatments—10 ml/kg of 6% HES, 10 ml/kg of 4% modified fluid gelatin (MFG), and 20 ml/kg of MFG—with comprehensive assessment of haematological, coagulation and renal parameters measured at baseline, multiple intervals post-infusion, and one week after treatment. All three protocols achieved effective volume expansion and maintained colloid osmotic pressure, with the higher-dose MFG producing the greatest haemodilution (reflected in haematocrit reduction) and a more pronounced thrombocytopenia compared to standard-dose MFG, though platelet counts remained within acceptable clinical ranges. Neither synthetic colloid produced clinically relevant changes in thromboelastography parameters, prothrombin time, activated partial thromboplastin time, fibrinogen concentration, serum creatinine, urine protein:creatinine ratio, or urine enzyme markers—suggesting both agents preserved haemostatic function and renal integrity in healthy animals. For practitioners selecting colloid support in critical equine cases, this evidence indicates MFG represents a viable alternative to HES without apparent safety disadvantages in normal physiology, though assessment in diseased or critically ill populations remains necessary before confidently extrapolating these findings to clinical practice.
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Practical Takeaways
- •Modified fluid gelatin can be used as an alternative to hydroxyethyl starch for volume expansion and oncotic support in equine patients, with comparable safety profiles
- •Both colloids are safe for routine fluid resuscitation in healthy horses with no clinically significant adverse effects on blood coagulation or renal function observed within 24 hours
- •Consider that higher doses of MFG (20 ml/kg) produce greater haemodilution than lower doses, which may be relevant when selecting infusion volumes for specific clinical scenarios
Key Findings
- •All three treatments (HES 10 ml/kg, MFG 10 ml/kg, MFG 20 ml/kg) produced significant haemodilution and increases in colloid osmotic pressure
- •Modified fluid gelatin at 20 ml/kg produced greater haematocrit reduction and platelet count decrease compared to 10 ml/kg MFG and HES
- •No clinically relevant differences were observed in thromboelastography parameters, prothrombin time, activated partial thromboplastin time, or fibrinogen concentration between treatments
- •Neither MFG nor HES produced significant changes in serum creatinine, urine protein:creatinine ratio, or urine γ-glutamyltransferase:creatinine ratio at 24 hours post-infusion