SHEEP BLOOD COAGULATION VALUES 
M. L. Povar* 
Twenty-five mature sheep were selected at random 
from a flock of about 100 animals used for artificial 
lung test and evaluation. Coagulation values were estab- 
lished for these 25 animals and compared with those of 
normal human adults. While most values were compa- 
rable to man, certain significant differences were found. 
The hemostatic system of the sheep showed a marked 
decreased fibrinolytic activity and an increased platelet 
number and adhesiveness. These factors were probably 
responsible for the commonly observed lack of excessive 
bleeding in sheep. The increases noted in factor V and 
VIII levels were not great enough to certainly suggest 
a tendency toward thrombosis. 
INTRODUCTION 
If sheep are to be used effectively as animal 
models in the evaluations of artificial lungs 
more has to be known about the coagulability of 
sheep blood. A study conducted at Brown Uni- 
versity has already provided some information 
on the subject.^ The coagulation profile of sheep 
blood was determined for a group of 25 mature 
western Rambouillet-Columbia cross non-bred 
ewes that were part of a flock used by the Arti- 
ficial Lung Test and Evaluation Facility 
(Table I) . 
Some of the data on the blood clotting factors 
of sheep were markedly different from the 
human blood samples used as controls. Those 
factors believed to be of special importance will 
be discussed. 
The methods and procedure for establishing 
the profile were described in detail in the pre- 
vious publication. It should be emphasized, how- 
ever, that blood samples were taken from the 
same and different individuals over a period of 
several weeks. This was done to increase the re- 
liability of some of the data collected, because 
Morag et al. have demonstrated that coagulation 
time varied somewhat from one individual 
sheep to another and among different breeds. 
* Brown University, Providence, Rhode Island. 
Small but significant day-to-day and week-to- 
week differences were also noted. They also 
found that prothrombin time varied signifi- 
cantly in sheep of different origins and in sam- 
ples drawn on different days and weeks from 
the same sheep.^ 
RESULTS AND DISCUSSION 
In the Brown University sheep, the clotting 
time was similar to that of man. Whole blood 
clotting time in glass ranged from 5 to 15 min- 
utes, while the same test in plastic ranged from 
5 to 57 minutes. These results differ markedly 
from those of Didisheim et al. who found that 
clotting time in plastic was equal to that in 
glass.^ However, their report was based on only 
one measurement in one sheep. 
Whole blood lysis did not occur in a period of 
24 hours in the sheep blood while the human 
blood controls varied from 0-20% in 24 hours. 
The uniform total lack of spontaneous lysis sug- 
gests very low fibrinolytic activity. 
Factor V values ranged from 160-800% of 
control compared to the human blood ranging 
from 60-140%. 
Factor VIII values for sheep ranged from 
440-1650% of control compared to human blood 
which ranged from 50-200% of control. These 
markedly higher Factor V and VIII values for 
the sheep might suggest some "increased tenden- 
cy to coagulate" as some authors consider eleva- 
tion of Factor V or VIII as predisposing to 
thrombosis.* 
The platelet count for sheep ranged from 
260,000-740,000 per cmm while the human 
blood control ranged from 200,000-400,000 per 
cmm. 
The platelet adhesiveness in sheep varied 
from 58.3 to 96.9% adhered compared to human 
blood platelets which varied from 18 to 60% ad- 
489 
