Low-molecular-weight heparin dosage in newborn foals.

The research explored whether newborn foals require higher dosages of low-molecular-weight heparin (LMWH), typically used to prevent blood clots, compared to adult horses. Results demonstrated that young foals do indeed necessitate greater doses to achieve effective levels of the drug in their systems.

Methodology

• The study conducted both experimental and clinical research. It examined 18 healthy and 11 septic (diseased) newborn foals.
• The healthy foals were randomly divided into two groups. The first group was given a dose of 50 IU/kg of a type of LMWH known as dalteparin, while the second group received 100 IU/kg of the same drug. The dosages were administered subcutaneously (under the skin) once daily for three days.
• Blood samples were obtained from the foals before, and at several intervals (3, 6, 27, and 51 hours) after the initial LMWH administration.
• Parameters including plasma antifactor-Xa activity, which denotes the effect of heparin, and other hemostatic and hematologic parameters, which would help assess the risk of bleeding, were measured.
• In the clinical phase of the study, the septic foals were unknowingly treated with either a placebo (saline) or given a 100 IU/kg dose of dalteparin for three days.
• The same parameters as in the experimental part of the study were assessed before and after the treatment.

Findings

• The study revealed that the antifactor-Xa activity in the plasma of the healthy foals was below the desired prophylactic level when given the dosage suitable for adults (50 IU/kg).
• When administered double the adult dosage (100 IU/kg), the foals achieved the desired antifactor-Xa activity levels, indicating that a higher dosage is necessary for effective treatment.
• No bleeding or erythrocyte-related complications were reported with either dosage used in the study.
• The clinical investigation of the septic foals showed that only 4 out of 6 treated with dalteparin had the optimal plasma antifactor-Xa activity for preventive care.

Conclusion

Equine neonates (newborn foals) require higher dosages of low-molecular-weight heparin compared to adults to achieve the desired preventive levels of the drug in their system. Thus, the dosage guidelines should be reconsidered for neonate foals, particularly those at a high risk of developing hypercoagulable states or disseminated intravascular coagulation (clotting of blood throughout the bloodstream).