Would it be a German Shepard? I mean the most sensitive nose. Also, how does it compare to human noses? I searched, but am not going to look through 40 pages of threads, so my apologies if it’s been asked, which I’m sure it has. I also googled and looked through a couple pages and came up with nothing.
According to this article on Wikipedia, that distinction belongs to the bloodhound. This jibes well with my memory of things I’ve read on the subject.
I opened this thread to say I thought it was the bloodhound, but Q.E.D. beat me to it. I think beagles are right up there, too - a vet I once worked with referred to them as “a nose on legs”.
I think the cops use German Shepherds a lot not because of the nose so much, but because it’s an intimidating strong dog that also has been bred for trainability. They aren’t used so much as “Find the fugitive, Fido!” as they are “You can put down the knife or I can let the dog go.” I know of a story in my old neighborhood when a kid at my school called the cops on a breakin, and it was “You can come back down the embankment, or I can let the dog loose.” He came back.
Good point. They are rather intimidating, loud dogs.
Good small story, too. I’ve seen similar happenings on COPS a few times myself. They let that dog loose, it’s all over. lol
The same article also notes that the nose of a bloodhound is “ten to a hundred million times more sensitive than a human’s”, to answer the OP’s second question.
As an aside I’ve heard that rats have much more acute noses than dogs in terms of absolute sensitivity. I have no cite for this.
I believe it goes bloodhound and then basset hound for the gold and silver of canine sense of smell.
As an addendum to the Bloodhound having the best nose - the reason why is not in the nose but in the make-up of the jowels. The slobber and excess skin in the jowels actually allows the bloodhound to trap scents that are in the air instead of attached onto something tangible. I’ll look for a cite but I believe I found this tidbit on Animal planet when they were profiling the bloodhounds.
The long ears on these kinds of dogs also help trap scents, according to my beagle book.
Intimidating yes. Loud? Not really. Certainly when they do bark they grab your attention but on the whole they are rather quiet dogs not given to yapping much. Indeed this makes them even more intimidating in my view. German Shepherds have a distinctive intelligence in their gaze and when one is staring you down it can be disconcerting to say the least. That they generally remain quiet (or perhaps a deep throated growl more felt than heard) while doing so only serves to increase their menace. Sort of a , “I know I am going to kick your ass and you know it so why bother talking about it?” Of course a well trained Shepherd will bark on command (or it just knows when the appropriate time is) and can spout off specifically to intimidate kids off embankments and the like without having to actually go get them.
Beagles on the other hand are about the chattiest dog I have ever seen. They seem to love the sound of their own voices and a distinctive voice it is too (all hounds seem to have that unique voice).
[sub]Whack-a-Mole is a lifetime German Shepherd owner[/sub]
I had a beagle years ago and he didn’t bark a whole lot but boy, could he howl!
One of the most woeful sounds I’ve ever heard, and even giving him a hug wouldn’t stop him when he got into the mood.
Sure miss him. 
I have autopsied a felon who had police dog bites, but got away.
Drowned swimming a river.
According to Wikipedia:
Well, I just mean when they are in action. Like when a cop releases them after the criminal, they’re pretty damn loud and vicious sounding.