SummaryThe effects of centrifugation force and time upon platelets function, mean platelet volume and platelet yield were compared with whole blood platelet counts and size in citrated blood samples from the bovine, canine, caprine, equine, feline, ovine and porcine species. The results were similar, for a given species, irregardless of sample volume. Bovine, caprine, feline and ovine platelet yields and mean platelet volumes were maximal when platelet-rich plasma was prepared using longer centrifugation times and lower gravitational forces. Canine, equine and porcine platelet yields and mean platelet volumes were maximal when platelet-rich plasma was prepared using shorter centrifugation times and higher gravitational forces. Platelet aggregation to adenosine diphosphate or arachidonic add was not effected by the method of platelet-rich plasma preparation in bovine, caprine, feline, ovine or pordne platelets. Equine platelet aggregation was maximal when platelet-rich plasma was prepared using longer centrifugation times and lower gravitational forces. Canine platelet aggregation, particularly arachidonic add-induced aggregation, was maximal when platelet-rich plasma was prepared using short centrifugation times and higher gravitational forces. It appeared that the effects of centrifugation parameters upon platelet yield depended upon the relative difference between platelet and red blood cell volumes.

No abstract

Summary Whole blood platelet counts, coagulation profiles and in vitro platelet function tests were monitored in newborn foals during the first week of life. Platelet counts, mean platelet volumes and thrombin‐induced malondialdehyde production were not different from adult mares. Prothrombin and partial thromboplastin times were slightly, but not significantly, longer for neonatal blood samples than for mare samples. Platelet aggregation responses to serotonin, arachidonic acid or adrenaline did not change during the study. On the other hand, adenosine diphosphate‐induced aggregation and collagen‐induced aggregation increased progressively over the first week of life. Adrenaline exposure diminished adenosine diphosphate‐induced aggregation only during the first 12 h of life. The results of this study indicate that the haemostatic mechanisms of equine neonates are immature at birth and that, during the maturation period, the equine neonate may be at risk of platelet‐associated haemorrhagic disorders.