Zylkene is a complementary feed for cats and dogs that contains a natural product derived from casein, a protein in milk. It is a molecule well known to promote the relaxation of newborns after breastfeeding. Since its launch Zylkene has become a familiar product for veterinarians, behaviourists, nurses and pet owners world wide. It helps pets cope when facing unusual and unpredictable situations and can be used before occasions such as a change in their normal environment. Zylkene is palatable and easy to give: simply mix with food or give the whole capsule. It can be given daily and is both preservative and lactose free.