Investigations performed on laboratory animals are useful as background information to the target animal safety studies and they draw attention to potential target organs and functional alterations but they do not replace them. During the target animal safety studies the test item has to be the same to the product intended to be marketed including chemical structure, purity, composition, particle size and formulation. Similarly, the route of administration has to be the same proposed by the label. The aims of the target animals safety studies are to evaluate the tolerance level of the recommended and multiple dose levels of the product applied by the recommended administration route(s) and to determine the margin of safety for the test item which cannot induce undesribale side effects including clinical signs, haematological and clinical-chemistry changes. Tolerance studies are generally required if the product contains new active substance or even new salt, or if the product marketed will be useful on a new target animal species, or if the product will be applied dermally but its active substance absorbes from the treated surface inducing systemic effect.