Whether folklore or fact, many of us would like to believe that our dogs can detect unexplained or invisible presences, guided by a canine sixth sense. It's exciting, and comforting, to think a favorite dog is sensitive to a departed relative or friend.
But hard evidence of dogs' extrasensory perception is elusive and anecdotal. The 2009 book "Tails of the Afterlife," by Peggy Schmidt, chronicles multiple instances of unexplainable actions by dogs who apparently interact with something, or someone, unseen. For instance, she writes about a woman named Del Johnsen who left seven dogs and six cats when she passed away. Numerous witnesses believe she still visits her pets daily, and report seeing the animals suddenly gather in one spot, cats arching their backs and purring, dogs flopping over for a belly rub, wriggling in enjoyment, all of them sitting at attention and staring into the air before resuming their own activities. And Schmidt says her own Jack Russell terrier Pixie has repeatedly reacted to ghosts present in local buildings rumored to be haunted.
But your pet's so-called sixth sense may simply be the result of his keen hearing, exceptional nose, and a dog's eye view on the world that allows him to sense small movements that escape our attention. A dog's senses are keener, and different, than ours: His eyes detect more delicate movements; his sense of smell is 1,000 to 10,000 times more sensitive than a human's. He can hear much higher frequencies, and at four times the distance of a human with normal hearing.
Wild and domestic animals, including dogs, seemed to sense the impending Indian Ocean tsunami in 2004, displaying their distress with behavior changes and vocal warnings, and either ran for cover or refused to go outside. Some experts believe they could sense vibrational changes on land from impending the earthquakes before humans could.
Dogs' heightened sense of smell is credited with their ability to detect some cancers in humans. Service dogs who aid seizure-prone people are alert to subtle shifts in body smells and dilated pupils, signs that enable the dogs to warn their owners of a looming attack.