Excellent point. Thank you. I sure would like to see a video of the dogs "hitting".
Hi Dunlurking, It is really interesting and surprising at the same time.
The handler controls the dog continually by giving him verbal commands.
The dog {Eddie from England} I watched on video didn't run right to the spot where he ended up alerting to. He ran here and there, back and around the car, then made a wider loop in the area of the car, whistled at by his handler, went back to the car and then to the other side where he faced the drivers door and sat, very excitedly giving a loud bark to his handler.
I did allot of reading about how dogs sniff, and this is just a basic recap for you:
The death scent which cadaver dogs alert to is purely chemical. Each person has their unique 'death scent' which is a combination of chemicals and like a fingerprint. No two are exactly the same. These chemicals are combined with caverdine, and it has the odour which attracts the dog.
The chemical scent wafts up from the remains {or something which has been in direct contact with the corpse} into the air, and is strongest at the point of origin, becoming less strong further away from that point as the scent spreads out into the air.
The dog in his search starts having a hit of the scent reach a certain part of his nose and then another and he turns in that direction where more scent molecules enter his nose. His nose is very complicated and as more scent wafts reach him he starts to zone in on the source of where they are coming from.
He might lose it and have to refind it which is why I think they do some running around in the process.
At some point enough hits have entered his nose to where he comes directly to the origin of the scent. He then intuitively knows there is enough scent to be what he is looking for, and he alerts. It is impersonal to him as he is just doing what he has learned so he will be rewarded with something good to eat. Eddie always gets salmon with cream when he alerts.
I should also say that alerts are qualified as to strength and weakness. With 3 dogs barking at the same spot it sounds like it was a strong alert to me, from a layman's point of view.
PS: The other dog thread got closed so I posted this here as it is on topic. ;}