M. L. POVAR 
491 
i ° 1 1 1 \ 1 1 1 1 
0 I 2 3 4 5 6 7 
4 
HEPARIN TIME (Hours) 
INJECTED 
Fig. 1 — Clotting time of sheep blood after a single 
injection of heparin. 
of heparin is rapid and increases with higher 
blood concentrations. We have observed that 
injections of 10 mg/kg resulted in no apparent 
bleeding in the sheep and a return to normal 
clotting time v^ithin 24 hours. 
SUMMARY 
The results of this study do not confirm the 
opinions of Shea et al. that "rapid clotting ap- 
pears characteristic of sheep and that they are 
relatively insensitive to conventional doses of 
heparin.''^ On the contrary, clotting time proved 
comparable to that of man. The blood of the 
sheep in this study v^^as characterized by a low 
fibrinolytic activity, a possible increased tenden- 
cy toward "coagulation," and an active hemo- 
static system. 
REFERENCES 
1. Gajewski, J., and Povar, M. L. Blood coagula- 
tion values of sheep. Am. J. Vet. Res. 32:405-409, 
1971. 
2. MORAG, M., and Robertson Smith, D. The day- 
to-day variations in certain blood values and in 
blood coagulation times of healthy ewes. Rehuah 
Vet. 28:74-78, 1971. 
3. DiDiSHEiM, p., Hattovi, K., and Lewis, J. H. He- 
matologic and coagulation studies in various animal 
species. J. Lab. & Clin. Med. 53:866-875, 1959. 
4. Sherry, S. Thrombosis (Editorial). Circulation 
40:755-756, 1969. 
5. Shea, M. A., Indeglia, R. A., and Bernstein, E. F. 
Hematologic observation during perfusions in sheep. 
In Organ Perfusion and Preservation. Edited by 
J. C. Norman. Appleton-Century-Crofts, New York, 
1968, 899-909. 
DISCUSSION 
Questioner : Why did you use a dilution fac- 
tor of 1 to 200 in your factor rate dilutions? 
Secondly, why didn't you use a pool of sheep 
plasma instead of a human standard? 
Dr. Povar : At the beginning of the study, 
Dr. Gazewski had set up a procedure for run- 
ning these tests. The tests were run over a pe- 
riod of a month or more, and the funding ran 
out after that. No further tests nor work could 
be done on this. We're presenting this hoping to 
stimulate other people to carry on. There's a 
tremendous amount that isn't known about the 
procedure. I'm reporting what was done, and it 
is not in any way a comprehensive study. 
Questioner: I was just wondering why. In 
all the other tests, you used a dilution factor of 
1 to 10 for your factor assays, but when you did 
factor 8 assay you used a dilution factor of 1 to 
200. 
Dr. Povar: I can't answer that question. I 
don't know why that was done. 
W. J. Dodds, New York State Department of 
Health, Albany, N.Y. : I just have a small com- 
ment. What you're trying to tell us is that you 
feel the coagulation system or the hemostatic 
system of sheep is much more active than that 
of man. The point is that this is the case with 
most of the domestic animals whose coagulation 
has been studied. The system is more active. If, 
for example, you say that the dog has up to 10 
times the factor rate as man, then a dog with 
mild hemophilia and a 20% factor rate would 
be normal because he would have 200 % relative 
to people. However, these dogs have hemophilia 
and bleed. Therefore, you shouldn't use the 
term hypercoagulable with regard to factor 5 
and factor 8 levels because they're perfectly 
normal in sheep. 
Dr. Povar : No, we carefully worded that to 
suggest a possible tendency towards hypercoag- 
ulability. None of our results in the artificial 
