90 



THE TOXICITY OF CAFFEIN. 

 PUP NO. 6. 



Highest amount of caffein given, 362 mg per kilo. No autopsy. 



Examination of the results obtained in the experiments of series C shows that 

 young and growing dogs tolerate large amounts of caffein. In four subjects of this 

 series, Nos. 1, 2, 3, and 6, no effect was observed when moderately large amounts 

 (160 to 200 mg per kilo of caffein) were fed. Symptoms were noticed only when 

 these amounts of caffein were increased from 50 to 60 per cent. The other two dogs, 

 Nos. 4 and 5, of this series were less resistant, however, to caffein, as 0.16 gram of the 

 drug per kilo induced well-marked symptoms. Since these were fed meat, while Nos. 

 1, 2, and 3 received milk, the difference in toxicity may be due to the diet employed, 

 but No. 6, which likewise received a meat diet, failed to show the effects of caffein 

 when 200 mg per kilo were fed. On the other hand, it should be noticed that No. 1 

 died after receiving 360 mg per kilo, No. 2 survived a dose of 334 mg, while No. 3 died 

 after a dose of 322 mg per kilo of caffein. The fatal doses for Nos. 4, 5, and 6 were 287, 

 335, and 300 mg per kilo, respectively. Although the differences are too small to 

 justify any definite conclusion regarding the effect of a milk diet or of a meat diet on 

 the toxicity of caffein, the results nevertheless suggest a reasonable possibility that 

 caffein is more toxic to young dogs when on an exclusively meat diet than when fed 

 milk. It is perfectly evident, however, that the resistance to caffein in either case is 

 very great, almost twice that of adult subjects. As shown in series A and B, 125 to 

 175 mg per kilo proved fatal to all but two animals in these experiments, while 

 symptoms of toxicity appeared after much smaller doses. In other respects the 

 behavior of young dogs toward caffein was the same as that of the adult. In neither 

 case was cumulation nor tolerance observed under the conditions of these experi- 

 ments. The findings at autopsy were likewise similar, as gastro-enteritis was the 

 chief lesion observed on macroscopic examination. It might be mentioned, however, 



