Upon sensing an oncoming seizure, the dog may respond in a variety of ways such as whining, pawing, and remaining close to the owner. This distinctive behavior can alert and warn the person or their family that a seizure may soon occur. This behavior has been reported in a number of different breeds. It is possible that dogs can detect some change (for instance, an odor or tone of the voice) that warns them of an approaching seizure, similar to the way that certain symptoms warn some patients.
No scientific studies of seizure-alert dogs have been completed, however, so it remains uncertain whether dogs can reliably "sense" an impending seizure, including how often they are correct when they indicate that a seizure is coming and how often they fail to indicate an approaching seizure. It is likely that the accuracy of the dog's predictive skills will vary considerably for different patients and different dogs.