Re: Cadaver dogs and water?
I have been to some water trainings and have read about the subject, but have not trained my dog for that yet.
When a body decomposes underwater, it releases oils, gases, etc. that can be detected by a dog as scent on the surface. There are a lot of variables that affect the decomposition process, so it is difficult to quantify the limitations, but I believe some bodies have been located by dogs years after they went missing, and some in quite deep water.
Usually the dog and handler work from a boat. They travel a grid pattern in the area and if the dog gets into a cadaver scent plume it will display its natural alert behavior such as pawing at the water, whining, or some other action that the handler has learned to read. The handler interprets this behavior and guides the boat into the direction of stronger scent. When the scent is at its strongest, the dog performs its trained alert behavior, which might be barking or lying down to tell the handler that is where the source of the scent is coming from.
When a dog has alerted on a location, often a second dog will be brought in to work the area independently in order to confirm it. If so, then divers are advised where to look. With no water current or wind, the body could be directly below, but the handler normally has to interpret the conditions to predict where the body might be based on where the scent is the strongest at the surface. There is a lot more to it than this, but hopefully this gives you an idea of what is involved. The Cadaver Dog Handbook has a chapter devoted to water searches.
Jonathan & Benny