ATCvet code: QP53AC08
The formulation for the veterinary medicinal product is devised so that the active ingredient, cypermethrin, is slowly released onto the surface of the tag. As the exposed chemical is removed, more cypermethrin is released onto the surface. Thus, the tag acts as a constant reservoir of insecticide throughout the season.
The active ingredient is lipophilic and is thus strongly bound to the sebum or natural oil present in the animal's coat and on the surface of the skin. Natural body movements - grooming and rubbing against other cattle - transfer the insecticide onto the hairs of the coat. This disperses the active ingredient all over the animal, effectively giving the whole-body protection against flies within 24 to 48 hours. The binding of the cypermethrin onto the sebum ensures a high degree of rain fastness.
Cypermethrin acts principally as a contact insecticide. Flies therefore have to come into contact with the chemical to be killed so it is normal to see a few on a tagged animal.
Flies landing on a tagged animal will pick up the insecticide on their feet or bodies. They then leave quickly as the chemical acts as a repellent. The flies normally leave before they have had time to bite, feed or otherwise annoy the animal. As the chemical on the flies is absorbed, they become hyperactive and die within a few minutes.