Topical therapy locally acting is extremely important in the management of many dermatological conditions. Shampoos are nowadays widely used in veterinary dermatology. Traditional shampoo formulations are composed of surfactants cleansing agents, foaming agents and conditioners as well as thickeners, softeners, sequestering agents, preservatives, fragrance and sometimes opacifiers and colouring additives 1. Surfactants are amphophilic molecules, i. Surfactants are composed of a hydrophilic part hydrophilic "head" and a lipophilic part "lipophilic tail".
In water, surfactants form micelle structures. These structures correspond to a spontaneous molecular arrangement of the amphiphilic molecules. The micelle formation process explains many of the surfactant properties and particularly their ability to emulsify, render soluble and disperse oils, dirty and debris.
Surfactants can be classified into 4 groups, according to their ionic nature: anionic, cationic, non-ionic amphoteric surfactants. Pet shampoos have to ensure excellent cleansing of the hair and skin, leaving them soft, supple, lustrous and easy to manage. A specifically formulated combinations of surfactants is necessary in order to combine superior cleansing properties and a perfect local tolerance on canine and feline skin.
Similarly, except for some very specific shampoos, pet shampoos have a physiological pH adapted to the canine and feline skin. Another important feature of pet shampoos is ease of rinsing, because surfactants can induce skin irritation when they are not totally removed by rinsing and also, because dogs and cats contrary to humans often lick their fur ingesting shampoo residues.
The local tolerance of the formula is assessed by using experimental models with alternative in vitro methods if the formula ingredients are irritant, and, then using standardized in vivo tests which maximize the potential side effects of the formula.
