SCENT THEORY

Presented by Kris BlackCSSTand

Santa Clara County Sheriff Search and Rescue

Adaptations and Illustrations from the Cadaver Dog Handbook

Topics• Olfactory system• Raft Theory • Scent Theory• Ground Scent Picture• Air/Scent movement• Summary • Practical Applications

Canine Olfactory• 125 – 400 million olfactory cells• 1/8 of canine brain devoted to olfactory• 44 times more receptors (man has 5 million)• smell memory 8 times greater

Portion of our brain devoted to scent

Portion of the canine brain devoted to scent

Dachshund - 125 million receptor cells

Greater capacity for scent work

Fox Terrier - 147 million receptor cells German Shepherd - 225 million receptor cells

R.S. Eden and Eden Consulting Group

Limited capacity for scent work

CONSIDER THE TOOL

Raft TheoryBill Syrotuck

• raft = group of cells• rafts = 14 microns / same as

smoke• body gives off heat • skin cells shed constantly• 40,000/min• bacteria break down cell

proteins• cell proteins float• currents move rafts upward

Theoretical Scent Pictures

No Wind

Wind

.

Sun

Clouds

Coning Plume• What most people are familiar with• Stable Air• Early mornings, late afternoons just before

sunset• Spreads out in a Horizontal 3 dimensional

cone carried downwind of the subject • Best scenting condition

Coning Plume

Ground Scent• Cold drops scent to ground• Sticks to crushed vegetation• Settles in disturbed earth

WIND

Thermal Lift

Looping Plume

• Occurs in very hot unstable air• Convection causes scent to rise up then drop

back down• Record time and wind direction• Need to check upper wind to help find new

search area

Looping Plume

Fanning Plume• Occurs in early morning, usually just before

sunrise on calm and clear nights.• In winter-scent rises till hits 86 degree layer• The scent cone compresses vertically and

fans out horizontally• May be over dogs head• May only hit scent on hills• Look for same height hills

Fanning Plume

WIND

Fumigating• Occurs in the morning when the air is still cool• As the sun begins warming the earth, the warm “unstable” air

rises and meets the cool air• Same as fanning, but where warm meets cold, the scent drops

to ground .

WIND

Lofting• Opposite of fumigating• Occurs when ground is cooling as the sun goes down• Warm air is still aloft• Scent travels up and spreads out• Employ “high ground” strategy

Lofting

Eddying• Occurs when scent is transported across

/ around a sharp corner

• Concentration of scent gets trapped in a circular turbulence

• Think of leaves in an entryway

EddyingWIND

Primary and Secondary Scent Pools

1 represents the primary pool 2 represents the secondary pool

Ground Water Flow

1 represents the primary pool 2 represents the secondary pool

Down Hill

1 represents the primary pool 2 represents the secondary pool

Hanging

Variable Winds

Tree LineWIND

Scent and Water

Water search

A represents the dog’s alert or indication

A REVIEW – if the sky is clear• Night = Fanning

• 1/2 hour before sunrise = Fumigating

• Daytime = Looping

• Sundown = Lofting

• At night with clouds and no inversion layer = Coning

A REVIEW – if it is cloudy• the scent is held down and closer to the ground

• clear skies cause scent to rise straight up from body

• clouds being high, medium, or low determines air stability

Summary• Rafts and decomp material fall constantly and are

effected by wind, temp, terrain, humidity

• Employee effective search techniques, keeping in mind the factors that effect the scent picture

• Continue to educate yourself on scent behavior and study your dogs reactions under various scenting conditions, so as to make yourself a more effective search team.