This one saved her owner's life by chewing on his cell phone after he had a diabetic seizure. She'd been trained:

A beagle's sense of smell is many hundreds of times as strong as a human's. During her training, Belle was taught to lick Weaver's nostrils to smell his breath, reading his ketone level. If something isn't right, Belle knows to start scratching Weaver's leg, warning him to adjust his sugar levels before a seizure comes on. For a worst-case scenario, Belle was taught to bite down on Weaver's cellphone - specifically on the number 9, which is programmed to dial 911. The training was costly - about $9,000 for nine months of intensive schooling - but as it happened, it was worth every penny the morning of Feb. 7.

And so her owner lived. But this is the part I like the most:

For her part, Belle was hardly the pedigreed hero in waiting. In fact, as a puppy, she was returned to the pet store twice by dissatisfied buyers before Weaver's friend mentioned seeing the doggy in the window.

Yes, that's a beagle: ornery, disobedient, mischievous, and profoundly loving. My kind of person, and my kind of dog.