Last week when lecturing at a seminar with Sarah Kalnajs, I watched an interesting video that Sarah showed. When her friend who had a history of cluster headaches was visiting her, Sarah’s dogs performed an unusual behavior. Typically they would hang back instead of interacting with the visitor but in this case they climbed onto his lap and kept licking his face, especially in the area of his right eye. At the time her friend did not have a headache but 10 minutes later he felt one coming on. As it was starting to occur, he warned that the dogs might start to become aggressive to him. His warning was based on a past dog he had owned. He’d owned the dog for at least a year prior to the start of his cluster headaches and the dog was a well-loved part of the family. Once he started having the headaches, the dog’s behavior changed. Just prior to the headaches, the dog would avoid him. But when the headaches occurred, the dog would become aggressive. As a result he had to rehome the dog with someone who didn’t have this type of medical condition.

Sarah’s dogs did not become aggressive to the visitor, they did however get more excited and lick the right eye, the area from which the headaches emanated, more vigorously.

Given that dogs have 20x more olfactory receptors than humans, it’s not surprising that they would pick up scents emanating from humans that we humans are completely unaware exist.