A comparative study of coagulation systems in newborn animals.

Appropriate animal experimentation can enhance our understanding of thrombotic and hemorrhagic problems in the human neonate. Which newborn animal species' coagulation system most closely resembles the human neonate is unknown. The objective of the study was to assess the newborn coagulation system in four animal species and compare them with the human neonate. Blood samples were drawn on days 1 and 7 of life from lambs (n = 10), piglets, (n = 12), rabbit pups (n = 12), and beagle pups (n = 7). Coagulation screening tests, specific factor assays, and specific inhibitors of the coagulation system were measured. All factor assays were expressed as a percent of the respective species pooled adult plasma. The results from the animals were compared to normal values from our laboratory for healthy full-term infants. The coagulation systems of all species tested, except the rabbit pup, were immature at birth with most factor levels being lower than the adult of their species. The coagulation systems were influenced by the postnatal age of the animal and the factor levels reached adult values in fewer days relative to the human. The coagulation system for the piglet most closely approximated the human neonate. The shared characteristics were prolonged screening tests, increased factor VIII:C, generally low levels for the contact and vitamin K-dependent factors, and low antithrombin III levels relative to the adult. The beagle pup also showed many similar characteristics but in contrast to the human neonate factor VIII:C and V were low on day 1 of life and prekallikrein was not measurable in the adult or newborn beagle.(ABSTRACT TRUNCATED AT 250 WORDS)