Haemostatic mechanisms of the newborn foal: Reduced platelet responsiveness

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.

Equine clinical neonatology in the USA: past, present and future

“…Intrauterine growth retardation is an important cause of morbidity and mortality in infants and foals, and the consequences of birth asphyxia can be equally devastating in both species (Johnson and Rossdale 1975;Dorand 1977). Platelet function is similar in the two species (Clemmons, Dorsey-Lee, Gorman and Sturtevant 1984). Susceptibility of the newborn to infection is even greater in foals than in infants, probably because of the total failure of IgG to cross the equine placenta.…”

Haemodynamic, pathological, haematological and behavioural changes during endotoxin infusion in equine neonates

“…Endotoxin interacts rapidly with the platelet membrane, and endotoxin induced platelet aggregation appears to be mediated by a plasma factor, which is most likely an element of the complement system (Walker and Casey 1985). The absence of consistent thrombocytopenia may be the result of an age related reduced platelet response (Clemmons, Dorsey-Lee, Gorman and Sturtevant 1984) or to a decreased complement activity (Hietala and Ardans 1987). The catheterisation protocol implemented can result in coagulopathy, as suggested by the increased APTT and positive FDP in a control foal at baseline.…”

Effects of dietary fish oil and alpha‐tocopherol supplementation on selected blood parameters and fatty acid profiles in mares and their foals

“…Our results have similarities with Aoki and Ishii (2012) who reported that the platelet count decreases in foals during the first week after birth. Although Clemmons, Dorsey‐Lee, Gorman, and Sturtevant (1984) noted that there was no difference in platelet count between adult horses and foal.…”