The dogs will lose their minds. They always do. Every Fourth of July in America, as children stay up past their bedtime to watch colors explode in the sky and adults sit on the back of pickup trucks drinking beer and marveling at a pyrotechnic technology 12 centuries old, pets across the country panic with every boom.

Sound phobias are very common for dogs—and cats—making this holiday a nightmare for millions of animals. “Half of the dogs in my practice are dealing with fireworks fear this week,” says veterinarian and animal clinical behavior resident Amy Learn, whose clinic in Richmond, Virginia, sees more than 2,000 clients annually. For many dogs, the nightmare has already begun. A quick search on Twitter shows people across the land complaining about neighbors popping fireworks off early. In Boston, where I live, they first started exploding in the middle of last week. The German shepherd next door has been pacing back and forth every night since, nails skittering across the floor.

That behavior is typical for dogs with loud noise phobia. Learn says you’ll know if your animal has abnormal fear of loud sounds if they don’t recover from the initial shock of hearing the sound right away. If your dog is pacing, howling, panting, and trying to run as far away from the sound as possible; if your cat is hiding, its ears cocked back, its eyes dilated, they need help. Every year around this date, people flock to Google to search “How to keep a dog calm during fireworks.” One answer that frequently shows up at the top of the results: anxiety shirts or thunder vests.

These come in two main designs—a spandex T-shirt that’s meant to give an animal a balanced hug, and a vest with straps designed to put pressure on particular parts of the body. “Their job is to squeeze,” Learn says. “It's postulated that it feels like a hug."

Animal anxiety shirts were directly inspired by research into humans with severe anxiety or autism. The insight that certain kinds of touch and pressure can have a calming effect was first popularized and championed by livestock behavior expert and autism-awareness-advocate Temple Grandin, who invented a “hug machine” for humans with autism after noticing the way a light squeeze calmed cows before slaughter. Grandin’s work is specifically called out on the website for Thundershirt, the major player in the animal anxiety wrap market. Deep Pressure Therapy is now widely used to help calm people with autism, and many different studies suggest the therapy shows real results.

But the science is less clear about whether pressure therapy really works for dogs.

Michelle Mullins, an animal behavior expert and board member of the International Association of Animal Behavior Consultants, first learned about animal anxiety shirts two decades ago. But they have only gone mainstream in the last 10 years with companies like Thundershirt. “As we often are wont to do when we look at science, we want to say if it works for humans it will work for our pets. In some cases it's true and in many cases it's not,” Mullins says. “Unfortunately we don’t have a huge amount of scientific studies about this.”

There’s only been one study to date into the use of anxiety shirts to deal with sound phobias, and it had a small sample size of 18 participants. Published in the Journal of Veterinary Behavior in 2013, the study compared owner-reported anxiety levels before and after prolonged use of anxiety wraps, and found that 89 percent of dog owners felt the shirts helped. Most importantly, the study found that even for those animals who saw no benefit, there were no adverse side effects. But one study is hardly conclusive evidence, and along with small sample size the study is also hindered by relying on self-reporting, which is often highly unreliable.