Scent discrimination describes a dogs ability to match one odor from the overall scent picture he's presented with to the one he's looking for. Dogs have a far superior ability in this respect. If you were trying to find the source of an icky smell in your house, you'd go sniffing all around moving your whole nose from place to place to try and find where the smell is stronger. Dogs can actually tell which way the odor is stronger based on the difference in concentration of scent molecules between one nostril and the other... the difference in location might only be one-quarter inch, but they can tell. Dogs can control the little flaps at the side of their nostrils to let in more or less air.
Comparing scenting capability between dogs and humans. Dogs have 25 to 60 times more scent receptors (depending on breed) than humans. The dog's devotes 40 times more of its brain to scenting than humans do. The area inside the nose that is devoted to turbinates is 60 times larger for a dog. Dogs can detect smells at 100 million times lower concentration than a human. Add to those physiological differences the way a dog's nose can move and process scent and the difference goes up as much as a dog being able to smell a million times better than you and I. Fred talked about a dog he'd trained that could find a gas pipeline leak, that was buried 20 feet underground and when analyzed by a mechanical sniffer at source was only 2 parts per million! That sounds amazing enough, but we now have evidence that dogs can detect odor in parts per TRILLION!
Different environmental conditions affect how odor molecules behave. You need to take these into account to train all the different conditions and remember they may increase or decrease the setup time.
- Temperature - Warmth expands the scent cone and causes the release of more molecules. Cold causes a reduction in the release of odor molecules.
- Organic vs. Synthetic - Generally organic sources respond more to warmth, with some notable exceptions (such as ether).
- Buried Sources - Soil conditions affect the release of odor. The ground is warmer than the air in the early evening, so more is released, but once it reaches the surface it stays close to the ground and may attach to dew or other moisture.
- Air Movement - Strong breeze creates a narrower, but longer scent cone. Slight breezes create shorter and wider scent cones. Air movement can channel odor, such as through cracks in the body or under a vehicle to the other side. Air conditioning units move air, as do heaters and fans.
- Air conditioners also dry the air reducing a dog's scenting ability - remember that need for moisture. So a dog kept in a running vehicle with the a/c running will have less capability as their noses dry out, unless the handler takes care to rehydrate the dogs nose.
- Quality and Quantity of Source - Higher concentration source will clearly put out more odor molecules. Don't assume that its easier to find source with a higher quantity of odor. Dogs have to learn to work through a super saturation of odor, just as they do for a miniscule amount.
- Packaging and Concealment - Be sure to vary the type of packaging you use.
- Humidity - High humidity means more molecules in the air and low humidity means less.
- Moisture - More moisture means more odor, lower moisture means less odor.
- OPTIMAL is Moderate Temperature and High Humidity... we are so blessed here in Washington state to have ideal scenting conditions most of the time.
During our practice today I buried an odor container in the ground - about six inches under. I arrived early to bury it so it had about 90 minutes setup time. There was a light rain, so plenty of moisture and humidity. It was evening, so the ground was warmer than the ambient air temperature. Birch is an organic source and there were 4 q-tips in a very open plastic package.
All three dogs found it quickly. Tucker was faster than Gimme, but he's more methodical and slower. Gimme blew by it numerous times. Grafton found it, paired with cheese, plus the ground had been disturbed by both Tucker and Gimme, releasing lots of odors and causing him to focus on the area sooner.
More to come...