Application of a Primary Toxic Solution

In most of our experiments, guinea pigs were sensitized by the use of a primary toxic solution (DNCB 1% in acetone). 

Before the application of the sensitizing solution on the neck of the guinea pig, the hairs are sheared and then shaved with an electric shaver. The solution is then applied with a cotton-swab every day for 12 days on a surface of approximately 3 cm in diameter. The degree of sensitization is evaluated 8 to 15 days later. 

Most of the guinea pigs are thus sensitized, if not we apply the same solution 3 to 6 times more. 

Contrary to what we have observed with other eczematogenic substances, we have never seen guinea pigs resistant to sensitization with DNCB. 

Nevertheless Chase (1941) shows that, according to the heredity of the animals, certain guinea pigs are extremely difficult to sensitize. However he adds that It is highly doubtful whether an absolute resistance will be encountered in any guinea pig under more intensive treatment, for instance repeated application of an oil or alcohol solution to the skin . 

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These facts prompted us to ask Can the young guinea pig be sensitized as easily as the adult guinea pig We sensitized new-born guinea pigs (2 days old and weighing between 60 and 80 gr.) by the epicutaneous application of a primary toxic solution of 1% DNCB in acetone, performed in the same manner as for adult guinea... 

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