A Note on the Desensitization of Guinea-Pigs. 



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A note on the desensitization of guinea-pigs. 

 By Alfred H. Caulfeild, M.B. 



[From the Department of Medical Research, University of Toronto.] 



During the course of certain experiments it so happened that 

 I desired to reinject a comparatively large number of laboratory 

 animals with bovine protein, and because of the danger of ana- 

 phylaxis I attempted to desensitize these before giving the large 

 amounts of protein which I subsequently wished to use. It was 

 in fact an endeavor to safely desensitize both rabbits and guinea- 

 pigs so that large amounts of protein could be reinjected sub- 

 cutaneously, intravenously and intrapleuraly. The results seemed 

 worth recording both because of their practical bearing and because 

 of one or two striking occurrences. 



The number of animals which came into consideration were 72 

 guinea-pigs. On account of the character of the initial or sensi- 

 tizing doses they should be divided into two groups, namely a set 

 of 30 and a set of 42. 



The former received the following initial injections: 



I 9 I 5. January 16. 2.5 c.c. subcutaneously. 



" 21. i.oc.c. " 



30. 0.5 c.c. 



February 2. 1.0 c.c. 



The set of 42 received only one initial dose of 0.5 c.c. on 

 January 22, 1915. 



The first reinjection (subcutaneous) was given on March 24, 

 1 91 5, an interval of 50 days. It is perhaps advisable to explain 

 the practical carrying out of the injections to make Chart I 

 clear. Both sets of guinea-pigs (all of which were numerically 

 tagged) were put in a large cage and the injections were carried 

 out by taking the animal most convenient, without regard to its 

 number, and transferring immediately after injection to a different 

 cage. The dose first tried was 0.02 c.c. protein diluted to 0.5 c.c. 

 with saline, but before the seventh animal was injected two guinea- 

 pigs were showing toxic symptoms and died immediately. As on 



