Many epilepsy patients swear by dogs like Angel. Special trained behaviors such as barking and licking are an apparent warning against risky activities like taking baths, climbing stairs, or driving a car. And cases like Specht’s, they may offer advance warning that could help stave off a seizure altogether.

But despite such anecdotal accounts, there is no proof that dogs can be trained to detect seizures, let alone predict their onset far enough in advance to tell humans about it. What’s more, even the dog trainers themselves don’t guarantee that their dogs can detect every seizure, and there is no regulation to ensure that the dogs were trained properly in the first place.

“Any good detector has positive value,” says Dr. Gary Mathern, a pediatric neurosurgeon at Mattel Children’s Hospital UCLA. “But as a physician, a key unanswered question is whether the dogs really work.”