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Special Senses

This seminar by Dr. N. Matthew Ellinwood explores the intricate world of canine olfaction, highlighting dogs' exceptional sensitivity to scents (up to 10 parts per billion) and their remarkable accuracy in detecting cancer (88-99%). The presentation covers various applications of dogs in disaster and emergency situations, such as search and rescue operations, forensic searches, and tracking lost individuals or pets. Dr. Ellinwood discusses the anatomical aspects of dog olfaction, emphasizing the unique olfactory receptors and their genetic control, illustrating why dogs can be over 100 million times more sensitive than humans.

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Special Senses

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  1. Special Senses Dr. N. Matthew Ellinwood, D.V.M., Ph.D. April 7, 2014 Iowa State University College of Agriculture and Life Sciences

  2. Olfaction • Dogs: Tested sensitivity to 10 parts per billion • Dogs as cancer detectors (88-99% accurate) • Used in disaster and emergency situations • Examples of situations where dogs are used include: Disaster searches, water searches, cadaver searches,area searches, trailing searches,snow/avalanche searches, forensic searches • Used as police dogs for things such as bomb and drug detection • Dogs are used to track criminals, lost persons, lost pets • Have ability to follow scents that are days old http://www.nasdak9.org/scullyvest.jpg

  3. For more information about search/rescue dogs… • www.cadaverdog.com • http://www.nasar.org/nasar/specialty_fields.php http://www.aboutxinjiang.com

  4. Overview • Olfaction • Taste

  5. Olfaction • Chemoreception • A quality shared with the sense of taste • Odorants • Chemicals of specific size and shape • Binding of odorants to receptors form the basis of olfaction

  6. Olfactory Anatomy

  7. Receptors, Odorants, and Olfaction • Each receptor senses just one kind of odorant • Receptor cilia bathed in a lipid mucous • Binding of odorant results in propagation of an action potential • Olfactory recptor cells turn over about every 40 days.

  8. Sensitivity of Olfaction • Size of the epithelium • Density of the epithelium • Variety of different receptors expressed • Controlled at the genetic level • Each population of distinct receptors is express from a specific gene

  9. Sensitivity of Olfaction • Size of the epithelium • Humans = 10 cm2 versus canine = 170 cm2 • Density of the epithelium • Canine 100X > than Human • Variety of different receptors expressed • Controlled at the genetic level • Olfactory receptors: the largest gene family • Each population of distinct receptors is express from a specific gene • Number of genes similar in dogs and humans • >60% of human genes are non-functional, versus <20% of canine genes

  10. Overall Canine Sensitivity • Results in potentially 100,000,000 more sensitive than humans

  11. Accessory Olfactory Reception • Vomeronasal organ • Located in the nose • Senses pheromones • Important in reproduction • Limited repertoire • Flehman response • A contraction of the muscles around the nose and mouth to increase air delivery to this structure • Seen in males and females around females in heat

  12. Flehman

  13. Central Processing of Odor Detection • Nerve impulses processed in and propagated from the olfactory bulb • Neural projections extend from the olfactory bulb to the limbic system and the hippocampus • Controls emotions (limbic system) • Memory (hippocampus)

  14. Role of Olfaction in Taste • Taste repertoire is very limited • Salt (low to non-existent in cats) • Sweet (very limited in cats) • Sour • Bitter • Umami • Odor is what gives us the rich sense of taste • Exhalation is the most important aspect of olfaction delivery involved in taste

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