Common and feared consequences of systemic inflammation in
horses include catheter induced venous diseases (Traub-Dargatz and
Dargatz, 1994; Dolente et al., 2005), and it is highly likely that the
activation of platelets is involved in this inflammatory state (Von
Hundelshausen and Weber, 2007). The inhibition of platelet function
may represent a valuable adjunct therapy to the routinely
performed inhibition of plasmic coagulation with heparins.
In humans, inhibition of platelet function is most commonly
achieved with acetylsalicylic acid, thienopyridins (P2Y12 antagonists)
or dual therapies with both substances (Bonzel et al., 2008).
The most commonly used thienopyridine is clopidogrel. Horses receiving
2 mg/kg bodyweight (BW) clopidogrel were shown to exhibit
a delayed inhibition commencing on the third day of therapy
(Brainard et al., 2011). The dosing regimen used in humans generally
comprises one loading dose of 4 to 8 mg/kg BW and subsequent
daily maintenance doses of 1 to 2 mg/kg BW clopidogrel
(Siller-Matula et al., 2010). With this loading dose, maximal platelet
inhibition was achieved after 4 h (Müller et al., 2003).