body are creating some kind of a scent that the dogs are detecting. reporter: and dogs have other superpowers, too. some have a nose for blood sugar. they help diabetics. others can predict seizures. watch as this dog pins down 16-year-old sissy cobb, an epileptic. the dog is telling you don t get up. reporter: shannon still passes out, but clover warns her every time. she s a gift from god that, i mean, science can t explain this. reporter: a new kind of superdog with an instinct to protect as old as the friendship between man and dog. ron claiborne, abc news, cochransville, pennsylvania. that s not the only thing they do. they act as braces. so they brace you when you are about to fall in case you do faint. if you get a sugar low, they ll go get juice on command. if you need to call 911, they ll go and get the phone for you. and then they are just so beautiful and wonderful to be around. that, too. they give you a lot of love. i know. we love dogs.
clover nuzzles shannon. just a friendly sign of affection? no. look closely. she keeps going. insistently until shannon lays down. shannon is about to pass out and clover s warning may have just saved her life. she cares enough to tell me that my heart is having a problem and to lay down. reporter: shannon has a rare condition in which her blood pressure drops suddenly. before clover, at her worst she fainted daily. she had to wear a helmet to protect herself. in a two-year span i had, 12, 13 concussions. they were life-threatening injuries. and, you know, one of those times, was it going to be the last time? we didn t know. reporter: then last year, shannon heard about dogs like clover, training at a nearby school. dogs that can detect swings in blood pressure. they start as puppies. about 1 in 5 show clover s talent. they are an elite. and no one knows quite how they do it. experts think they might smell the human body change. what we believe is happening is that the elec
i ll be there for you these five words i swear to you when you breathe, i want to be the air for you i ll be there for you i d live and i d die for you i ll steal the sun from the sky for you all right. now we want you to meet the superdogs who can smell your blood pressure and save lives. these dogs can actually sense when your pressure is too low and you are about to faint. it is hard to believe. we ve seen hero dogs before. but these pups actually intervene before there s a problem. abc s ron claiborne has more on these heroic canines. reporter: it s a common friendship. a young woman and her dog. shannon tomlinson and her 2-year-old lab, clover. but watch as something ordinary becomes extraordinary.
just a friendly sign of affection? no. look closely. she keeps going. insistently until shannon lays down. shannon is about to pass out and clover s warning may have just saved her life. she cares enough to tell me that my heart is having a problem and to lay down. reporter: shannon has a rare condition in which her blood pressure drops suddenly. before clover, at her worst she fainted daily. she had to wear a helmet to protect herself. in a two-year span i had, 12, 13 concussions. they were life-threatening injuries. and, you know, one of those times, was it going to be the last time? we didn t know. reporter: then last year, shannon heard about dogs like clover, training at a nearby school. dogs that can detect swings in blood pressure. they start as puppies. about 1 in 5 show clover s talent. they are an elite. and no one knows quite how they do it. experts think they might smell the human body change. what we believe is happening is that the electrical and the chemical