Low-molecular-weight heparin dose should be doubled in newborn foals

Introduction/Objectives: Heparin therapy is used in pediatric
human patients for prophylaxis of thromboembolic states, but
human babies need a higher dose than adults. Septic neonate foals
are at high risk of hypercoagulable state and DIC, and no information about heparin dose for equine neonates is available.
The objective was to assess whether neonatal foals need higher
doses of low-molecular-weight heparin (LMWH) than adults.
Methods: In an experimental study, 18 healthy foals were randomly distributed in 2 groups, receiving 50 IU/kg or 100 IU/kg of
dalteparin subcutaneously for 3 days. In a prospective clinical
study, another 11 septic foals were randomly treated either with
placebo or 100 IU/kg of dalteparin for 3 days. Blood samples were
collected at the beginning and after each administration. Plasma
antifactor-Xa activity and clotting times were measured in both
studies, closure time, PCV, hemoglobin concentration and platelet
count were measured in the experimental study and antithrombin
activity and D-dimer concentration in the clinical trial.
Results: In healthy foals, prophylactic plasma antifactor-Xa activity was only achieved when using the double dose (100 IU/kg),
with no hemorrhagic risks and erythrocyte-related complications.
Similar plasma antifactor-Xa activities were also achieved in septic
foals.
Discussion: Healthy neonatal foals need double dose of LMWH to
reach the same prophylactic plasma antifactor-Xa activity than
adult horses. In the clinical study, septic foals reached similar
plasma antifactor-Xa activity than healthy foals using the same
double dose of LMWH.
Conclusions: Equine neonates need higher doses of LMWH compared to adults to reach prophylactic heparinemia.