This specially designed shirt is a pressure wrap that applies a gentle, constant pressure on a dog’s torso. From real world experience, we know with certainty that Thundershirt DOES WORK. That is why we are able to offer a money-back guarantee. A survey of Thundershirt users shows that over 85% of dogs show significant improvement in anxiety symptoms when using Thundershirt. As for WHY Thundershirt's gentle pressure works to calm a dog…no one knows for sure. There are theories, but no scientific studies to prove them. According to some experts such as Dr. Temple Grandin, pressure has a calming effect on the nervous system. Using pressure to relieve anxiety has been a common practice for years. For example: • TTouch dog trainers use pressure to address a wide variety of anxieties. • Veterinarians use pressure to relax cattle when they are administering vaccinations. • People with Autism use pressure to relieve their persistent anxiety. Until now, there just hasn’t been a well-designed, inexpensive pressure wrap commonly used for canine anxiety. Thundershirt is changing that!