Harmony Pet Calming Spray for Dogs is fast-acting. This technology uses P.E.T. pheromone to help calm dogs by mimicking the maternal pheromone from momma dog to soothe her pups. This technology helps the pheromone quickly enter the nasal cavity, providing short term relief. Dogs of all ages recognize this calming pheromone for life. Helping dogs live in harmony where ever they go.