The effects of cytochalasin D and abciximab on hemostasis in canine whole blood assessed by thromboelastography and the PFA-100® platelet function analyzer system

Abstract

Abstract. The selective inhibition of platelet function in whole blood coagulation testing may allow insights into the nature of hypercoagulability in dogs with critical illness. To determine the effects of cytochalasin D and abciximab on hemostatic parameters in canine citrated whole blood, an in-vitro study was designed using thromboelastography (TEG) and a platelet function analyzer (PFA-100®). 8 clinically healthy mixed breed dogs donated blood that was anticoagulated with 3.2% sodium citrate in a 9:1 blood-to-citrate ratio. Addition of cytochalasin D to citrated whole blood from 6 dogs at concentrations ranging from 0 µg/ml to 10 µg/ml caused a maximal reduction of TEG maximum amplitude (MA) at a concentration of 7.5 µg/ml (52.7 ± 4.3 to 14.3 ± 7.8 mm). Addition of abciximab to canine citrated whole blood at concentrations of either 20 µg/ml or 40 µg/ ml did not affect the TEG tracing; however, addition of abciximab to citrated canine whole blood at concentrations of 10 µg/ ml and 20 µg/ml significantly prolonged PFA-100 closure times (72.5 ± 15 to 149.2 ± 91 sec and 275.6 ± 54 sec, respectively, P < 0.04). Inhibition of canine platelet function by cytochalasin D is demonstrated by TEG, but abciximab did not change TEG tracings. Abciximab does, however, inhibit platelet aggregation under shear stress as measured by the PFA-100. Inhibition of canine platelet function with cytochalasin D may allow further TEG studies in dogs with clinical disease.

Anti‐platelet therapy in small animal medicine

“…Platelet function recovers within three and a half hours of administration (Kageyama et al, 2001). In vitro, incubation of canine blood with abciximab prolongs PFA-100 â closure times (ADP-collagen cartridge) without significantly affecting thromboelastography (Brainard et al, 2011). In cats, a single study has evaluated abciximab in an arterial injury model, and demonstrated that a combination of aspirin and abciximab (0.25 mg/kg by intravenous bolus followed by an infusion of 0.125 lgÁkg/min) was more effective at inhibiting platelet function and preventing thrombus formation than aspirin alone.…”

Abnormal platelet activity in dogs and cats – impact and measurement

“…, Brainard et al . ). A citrated blood sample is added to a small cup (where activators of coagulation may or may not be added depending on the type of analysis to be performed), in which a pin is suspended. With TEG, the cup rotates which detects changes in torque of blood as a blood clot forms in the cup.…”

“…, Brainard et al . ). TEG with “platelet mapping” can better assess platelet function, which requires two TEG machines running concurrently with different activators including heparin, which can exclude the contribution of thrombin to maximum clot strength. (Craft et al .…”

Diagnosis and treatment of platelet hyperactivity in relation to thrombosis in dogs and cats

“…A recent study examined the in vitro effect of the fungal metabolite cytochalasin D and the monoclonal α IIb β 3 antibody abciximab on TEG analyses. The results showed that cytochalasin, but not abciximab changed TEG tracings . These studies emphasize a unique feature of the TEG assay, which suggests that for selected drugs, it could be utilized in targeting therapy of the patient toward a normalization of the patients TEG tracings and hereby tailor dosage to meet the requirement of the individual patient.…”