The discovery that squeezing pressure on the body helps to relieve anxiety is credited to animal behaviorist Temple Grandin. In 1965, Dr. Grandin invented a device she called a "hug machine", to help relieve her own autism spectrum anxiety. The calming effects of "deep touch pressure" have been documented for children with autism.
Deep touch pressure is believed to work by decreasing the body's “fight or flight” response, and by releasing hormones oxytocin, dopamine and serotonin.
Dog anxiety relief jackets and vests like the ThunderShirt are available to fit every size and shape of dog.