VETIQ Serene-UM Xtra has been especially formulated for dogs over 20kg and is formulated with natural ingredients for hyperactive or nervous dogs. VetIQ Serene-UM Xtra has been recommended by Veterinarians and can help calm and pacify your pet without the need for tranquilisers in a totally natural way and as it is not a sedative, it does not cause drowsiness. VetIQ Serene-UM Xtra works by controlling the underlying emotional state to calm your pet, so that behaviour learned from a stressful situation can be corrected through retraining. In essence, VetIQ Serene-UM Xtra treats the source of the problem not the symptom. Starts working 6-8 hours but for maximum effect allow 24-36 hours.