Thundershirt's patent design applies a constant pressure that creates a calming effect for dogs. These are perfect for your overly-excited or anxious dog! Studies have shown the use of the Thundershirt improves anxiety symptoms in 80% of dogs. The pressure has a calming effect on the nervous system. Excitability and hyperactivity (especially around strangers) is a common dog problem that can be addressed by simply putting the Thundershirt on your dog. The Thundershirt also helps with separation anxiety and travel anxiety.