It's small yet very agile and has a very acute sense of smell. (mypetneedsthat.com)
It may be that a dog's acute sense of smell allows him to detect changes in his person's body chemistry right before a seizure occurs, or maybe the dog, keenly tuned into his human, is alerted by behavior that is a little «off» prior to an incident. (dogcare.dailypuppy.com)
Sometimes called a nose with a dog attached, the Bloodhound boasts the most acute sense of smell of any other breed of dog! (dogpack.com)