What is Scent?
Scent is defined as a distinctive odor or perfume. When talking about human scent (or even scent of a prey species), you can think of it as being a distinctive odor derived from each individual's genetic makeup and the chemical activity that the genetic makeup causes within the individual's body. Because every individual differs genetically, we each have a unique individual scent. Additionally, we humans have microscopic mites and bacterial fauna living on the surface of our skin, which adds to our own odors, and we use different types of deodorants, lotions, laundry detergents to wash our clothing, etc., all of which further modifies our body odors.
Dogs can follow these individual and unique odors because all living creatures slough off dead skin cells (known as "rafts"). Humans drop thousands of rafts per second and up to 2 billion rafts per day. These rafts are approximately 0.014 mm in size, have negligible weight (~0.0000000245 oz), and have a shape similar to that of cornflake cereal. These rafts will not only bear our characteristic genetic odor, but also the vapors from all of the things that modify our characteristic odor. Thus, our scent is a complex mixture of a number of chemical odorants.
When tracking, a dog follows this complex mixture of odorants found in our skin rafts. However, this scent picture can be further modified by the surface upon which the skin rafts are found. For example, when tracking on vegetation, additional chemical odorants will be presented to the dog in the form of crushed vegetation (the destruction of plant cells with their own characteristic genetic odor) and the decomposers in the soil (usually bacteria) that will begin breaking down the damaged vegetation. When training "green" tracking dogs on vegetated surfaces, the handler does not necessarily know if the dog is learning to follow the pathway of crushed vegetation, the pathway of skin rafts, or the pathway of both combined. On hard surfaces, there is no vegetation and little to no bacterial presence, so dogs are forced to follow the odor of the skin rafts that have fallen upon that surface as the tracklayer walked by. Because there is less "scent" information available to the dog, the VST trial for tracking is much harder and has a lower pass rate than the TD trial held on a vegetated surface. We, as the dog's teammate, must keep in mind changes in the odor picture ("scent") on different surfaces so that we can help our dogs overcome sparse scent pictures.
Scent is defined as a distinctive odor or perfume. When talking about human scent (or even scent of a prey species), you can think of it as being a distinctive odor derived from each individual's genetic makeup and the chemical activity that the genetic makeup causes within the individual's body. Because every individual differs genetically, we each have a unique individual scent. Additionally, we humans have microscopic mites and bacterial fauna living on the surface of our skin, which adds to our own odors, and we use different types of deodorants, lotions, laundry detergents to wash our clothing, etc., all of which further modifies our body odors.
Dogs can follow these individual and unique odors because all living creatures slough off dead skin cells (known as "rafts"). Humans drop thousands of rafts per second and up to 2 billion rafts per day. These rafts are approximately 0.014 mm in size, have negligible weight (~0.0000000245 oz), and have a shape similar to that of cornflake cereal. These rafts will not only bear our characteristic genetic odor, but also the vapors from all of the things that modify our characteristic odor. Thus, our scent is a complex mixture of a number of chemical odorants.
When tracking, a dog follows this complex mixture of odorants found in our skin rafts. However, this scent picture can be further modified by the surface upon which the skin rafts are found. For example, when tracking on vegetation, additional chemical odorants will be presented to the dog in the form of crushed vegetation (the destruction of plant cells with their own characteristic genetic odor) and the decomposers in the soil (usually bacteria) that will begin breaking down the damaged vegetation. When training "green" tracking dogs on vegetated surfaces, the handler does not necessarily know if the dog is learning to follow the pathway of crushed vegetation, the pathway of skin rafts, or the pathway of both combined. On hard surfaces, there is no vegetation and little to no bacterial presence, so dogs are forced to follow the odor of the skin rafts that have fallen upon that surface as the tracklayer walked by. Because there is less "scent" information available to the dog, the VST trial for tracking is much harder and has a lower pass rate than the TD trial held on a vegetated surface. We, as the dog's teammate, must keep in mind changes in the odor picture ("scent") on different surfaces so that we can help our dogs overcome sparse scent pictures.
Comparison of AKC Tracking Tests
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Characteristics
Length Age # of Flags Surface Articles Cross-Tracks Obstacles Minimum Yardage per Leg Requirements Minimum Distance from Dog |
Tracking Dog (TD)
440 – 500 yards ½ - 2 hours 2 flags Consistent vegetation Leather glove or wallet at end None None 50 yards Certification 20 feet |
Tracking Dog Excellent (TDX)
800 – 1000 yards 3 – 5 hours 1 flag Fields – variable cover and terrain Four personal items – one at start two on track, leather glove or wallet at end. No plastic or metal. All drops more than 30 yards from turns, obstacles or cross-tracks Two widely spaced, two people walk across track At least two (fences, roads, water, hills, gullies, changes of cover, etc.) 50 yards TD 20 feet but may shorten for cover |
Variable Surface Test (VST)
600 – 800 yards 3 – 5 hours 1 flag Vegetated and at least two non-vegetated surfaces (concrete, asphalt, gravel, dirt, etc) Four non-personal items – one leather or fabric at start, two on track, one at end. Leather, fabric, metal and plastic, one dropped on non-vegetated surface. All at least 10 yards from turns. None required but tracks in public areas where unplanned cross-tracks are possible, even likely. None, but normal items such as stairs, ramps, etc may be used on track. 30 yards (15 yards vegetated on start) TD + 6 months 10 feet |