Comparative surfactant reactivity of canine and human stratum corneum: A plea for the use of the corneosurfametry bioassay

Comparative dermatology has paid little attention to the physiopathology of the stratum corneum. In this study, we investigated the responses of human and canine horny layers to marketed animal wash products by using the corn eosurfametry bioassay. Previous work has shown that, with increasing surfac tant aggressiveness to the stratum corneum, the colorimetric index of mildn ess (CIM) decreases, while both the corneosurfametry index (CSMI) and the o verall difference in corneosurfametry (ODC) increase. In the present study, stratum corneum reactivity to wash products and inter-individual variabili ty were significantly higher in humans than in dogs. For the three corneosu rfametry variables, linear correlations were found between data gathered in the two panel groups. In conclusion, this pilot study suggests that mean s tratum corneum reactivity to surfactants is stronger in humans than in dogs . Inter-individual variation, indicative of sensitive skin, also appears to be broader in humans. As a consequence, data gathered from dogs by using t he corneosurfametry bioassay cannot be extrapolated to humans. Such variati on between species could be important in the assessment of product safety a nd in supporting claims for mildness.