The blood platelets in canine anaphylaxis.

Abstract

It is well recognized that in canine anaphylaxis the blood generally becomes incoagulable, often remaining fluid for days. This loss of coagulability of the blood has been attributed to an excess of antithrobin or to a diminution of thromboplastin. Recently one of us noted, 1 in connection with studies on the blood fibrin in canine anaphylaxis, that the addition of a small quantity of platelets to the clotting solution, into which the oxalated anaphylactic plasma had been discharged, induced prompt coagulation in samples which otherwise (in controls) remained uncoagulated for hours, sometimes for days. This suggested the desirability of making platelet counts. While a diminution in the platelets in anaphylaxis has been reported, 2 , 3 we were especially interested in the counts obtained in fatal canine anaphylaxis, particularly since changes in the coagulability of the blood are more prominent in the dog than in other animals.

Of a number of current methods employed in counting platelets we found none that gave us entirely satisfactory results. We finally adopted the method of Rees and Ecker, 4 using, however, instead of their diluting fluid that recommended by Leake and Guy. 5 This combination gave us entirely satisfactory checks. The time allowed for settling in the counting chamber was reduced to a constant minimum to prevent undue evaporation of the diluting fluid and to insure strictly relative counts. The blood samples were obtained from the common carotid artery by incision. A rubber covered artery clamp was placed proximal to the opening and the blood was allowed to flow freely before the samples were taken. The animals were sensitized to horse serum,

0.3 cc. per kilo subcutaneously, followed on the third day with the same dose intracardially, and the shocking dose, 1 to 2 cc. per kilo, was injected intracardially.