A STUDY OF THE CAUSE OF SUDDEN DEATH FOLLOW- 
ING THE INJECTION OF HORSE SERUM. 
By Milton J. Rosen au, 
Passed Assistant Surgeon, Director Hygienic Laboratory, TJ . S. Public Health and Marine- 
Hospital Service. 
and 
John F. Anderson, 
Passed Assistant Surgeon, Assistant Director Hygienic Laboratory , U. S. Public Health and 
Marine-Hospital Service. 
It has long been known that the blood of certain animals is 
poisonous when transfused or injected into certain other species. 
Many instances might be cited showing that the blood serum of 
one animal has poisonous properties when injected into an animal 
of another species. But the blood serum of the horse apparently 
lacks such poisonous action. Very large quantities of the blood 
serum of the horse may be injected into man, rabbits, guinea pigs, 
and many other animals without serious inconvenience, except 
occasionally a slight reaction at the site of inoculation. 
In a certain proportion of cases the injection of horse serum into 
man is followed by urticarial eruptions, joint pains, fever, swelling 
of the lymph nodes, edema, and albuminuria. This reaction, which 
appears after an incubation period of eight to thirteen days, has 
been termed by Pirquet and Schick the “ serum disease." 
In exceptional instances sudden death has followed an injection of 
horse serum in man. 
These studies were taken up in October, 1905, in order to throw 
light upon the cause of this unfortunate accident. We have shown 
that ordinarily horse serum is a comparatively bland and harmless 
substance when injected into certain animals; but these animals may 
be rendered so susceptible that an injection of horse serum may 
produce sudden death or severe symptoms. For example, large 
quantities of horse serum may be injected subcutaneously or into the 
peritoneal cavity of a guinea pig without apparently causing the 
animal the least inconvenience. However, if a guinea pig is injected 
with a small quantity, say Hu c. c., of horse serum and after the 
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