Abney Canine Tracking Guide

Training the All-Purpose Tracker
1. Auflage 2014
ISBN: 978-1-59378-654-0
Verlag: CompanionHouse Books
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 120 Seiten

Reihe: Country Dog

Canine Tracking Guide details the two most common uses of the canine nose: following blood trails for wounded game and tracking humans (from lost children and missing hikers, to escaped convicts). The author explains the concept of human scent and how the amazing canine nose functions and then elaborates on the basic training principles, commands, exercises and patterns used in tracking work. Whether a reader is working with hunting dogs, police dogs, cadaver dogs or competition dog, this guide offers the correct information needed for every tracking pursuit.

Author Don Abney (New Orleans, LA) is a court certified-expert in the field of canine training and tracking. Abney has been a master trainer in obedience, search and rescue , tracking, hunting and detector dogs for over 25 years.

Autoren/Hrsg.

Abney, Don

Leseproben

Chapter
1

The Dog’s Nose

Of all the dog’s senses, the sense of smell is the most well developed, and the one on which he depends most throughout his life. Puppies are deaf and blind at birth and remain so for the first ten days of life, but they can locate their source of food (mom) within minutes of being delivered. When a birthing female leaves the den or whelping box to relieve herself, eat, or exercise, her puppies instinctively find a corner and bunch up for warmth. The pups know when she returns and can locate her, despite not being able to see or hear, because of their acute sense of smell.

The sense of smell is vital to mature dogs’ social skills. It enables them to quickly distinguish between known and unknown humans and other animals. In the male of the species, it is a primary factor in his ability to determine whether a female is in heat and receptive to mating. A dog also can smell certain changes in human body chemistry that influence his behavior. For example, in a state of fear or panic the human body produces adrenaline. Dogs can sense the odor of adrenaline—the smell of fear—which provokes reactions ranging from heightened alertness to aggression. Through a combination of instinct and training, a tracking dog will be more motivated and work more intensely when searching for a person who is exhibiting fear.

Human Versus Canine Smell

A. First sense to develop:

Dog         Smell

Human    Touch

B. Primary sense for recognition:

Dog         Smell

Human    Sight

C. Last sense to fail:

Dog         Smell

Human    Touch/taste

How Keen Is the Dog’s Sense of Smell?

By various calculations over the years, many individuals have estimated that dogs can detect scent ten times better than humans can. In truth, no one knows the exact capacity or efficiency of the dog’s nose, because no man-made instrument is capable of measuring it. We can only speculate as to what degree a dog’s nose is more sensitive than a human’s, but there is evidence that the dog can detect and identify scent better than any instrument devised by humans.

Estimates of efficiency differ for different odors and different breeds. But even though some dogs’ ability is better than others’, the dog’s keen sense of smell is definitely a genetic trait. A 1972 study of German Wirehaired Pointers by G. Geiger, using a sample of 613 males and 573 females, concluded that 46 percent of the breed’s tracking ability and 39 percent of its scenting ability are inherited, whether the offspring come from working or nonworking parents.

When the cells of the nose are measured in the area of one square inch, the dog, with one sniff, allows more than 10,000 scents to be distinguished, categorized, and memorized. With that same sniff, the human can distinguish only 4,000 scents.

In Milo Pearsall and Hugo Verbruggen’s book Scent, the sensitivity of the dog’s nose is described as follows: “The dog can smell some odors at as much as one part per trillion (1 in 1,000,000,000,000).” The following example is given:

One of the substances released by human perspiration is butyric acid. If one gram of this chemical (a small drop in the bottom of a teaspoon) were to be spread throughout a ten-story building, a person could smell it at the window only at the moment of release. If this same amount were spread over the entire city of Philadelphia, a dog could smell it anywhere, even up to an altitude of 300 feet.

This example shows that a dog does not suffer from nose fatigue or acclimation to any specific scent. A human, on the other hand, acclimates to the smells around him. When you walk into a florist shop, the combined fragrance of the flowers and plants can be overwhelming. It is very difficult for humans to identify and locate any specific scent in this powerful mixture of perfumes. If you were to remain in the shop for a day, however, like those who work there, the powerful smell of fresh flowers would fade, and you would not notice the aroma as you did when you first walked in. The dog, on the other hand, can smell the individual scents and identify their origins.

Another impressive nose is that of the Basset Hound. Taking a hound for a leisurely walk can be a challenge, as the dog always wants to stop and sniff.

The long ears of the scenthound are designed to help gather and hold scent.

The Anatomy of Smell

The ability to detect subtle odors and follow a scent depends on cellular structures called olfactory receptor cells. The olfactory receptor cells are found in the moist lining of the entire length of a dog’s nasal cavity. Protruding from the surface of the olfactory cells are hairlike fibers known as cilia. The cilia are believed to be the part of the cell that is stimulated by the molecules of various airborne odors. The dog’s nose contains approximately 220 million olfactory cells, with 120 to 200 cilia per cell. By comparison, a human’s nose contains approximately 5 million olfactory cells, with six to eight cilia per cell. This would give the dog an estimated olfactory capacity a thousand times greater than that of a human. (By cilia count alone, a human’s sense of smell comes closest to that of the frog. A frog’s nose contains six to twelve cilia per cell, leading some to conclude that even frogs have a better sense of smell than humans do.)

Mucus membranes in the lining of the dog’s nose secrete a thin clear layer of mucus. In addition to its dirt-trapping function, the mucus keeps the olfactory cells moist and helps capture, absorb, and dissolve scent molecules, concentrating them in the cilia as the dog inhales or sniffs. The cilia stimulate the olfactory receptor cells, which are connected by a rich network of olfactory nerves to the olfactory lobe in the dog’s brain, where the scent molecules are identified and then categorized in the dog’s memory.

The dog also has a secondary olfactory cavity, called the vomeronasal organ (VMO) or Jacobson’s organ. This pair of fluid-filled sacs, above the roof of the mouth behind the incisors, is also lined with olfactory receptor cells, but unlike the cells in the nasal cavity, the VMO cells have tiny cellular protuberances instead of cilia that are stimulated by odor molecules. VMO cells transmit impulses directly to the olfactory lobe and, it is believed, to the parts of the dog’s brain that are associated with sexual behavior and the detection of pheromones, or chemicals that trigger a natural behavioral response in other animals. The vomeronasal nerve, along which these impulses are carried, may also be stimulated without inhaling, such as when the dog’s nose is submerged in water. The dog’s well-developed VMO could explain dogs’ superior ability to recognize individual people and other animals by scent.

A third sensory nerve, the trigeminal nerve, lies at the back of the nasal cavity. This nerve sends impulses to the brain to indicate the presence of foreign material within the nasal cavity, which triggers a sneeze. When a dog sneezes or blows his nose, he clears debris that may be interfering with his ability to detect scent, and he distributes additional moisture to the olfactory cells.

Brain anatomy also helps explain why dogs’ sense of smell is so much better than humans’. Researchers say the olfactory bulb of the human brain is approximately the size of a pea. A dog’s olfactory lobe is up to eight times larger; a bloodhound’s olfactory lobe, for example, is about the size of your thumb.

Another anatomical contrast between human and dog involves the capacity of the nasal cavities. The volume of air required to fill the human nose is 1.5 cubic inches; the volume of air required to fill the average dog’s nose is 6 cubic inches. The dog therefore has four times as much air swirling over his olfactory receptors. When a dog sniffs, he can hold several bursts of airborne scent molecules in the nasal cavity at once.

The diagram in figure A is a cross-section of the dog’s nasal cavity and indicates the locations of the olfactory, trigeminal, and vomeronasal structures.

During the normal breathing cycle (figure B), air is taken in through the nostrils, flows upward, curves approximately midway in the canal, and is directed into the lungs.

During the sniffing cycle (figure C), air is taken forcefully through the nostrils and fills the entire cavity. Sniffing causes air to be pushed against the upper and back walls of the cavity. Inhaled air stays in the nasal passages longer, so more scent molecules can be accumulated and identified. The air then curves and passes into the lungs.

Factors That Affect the Sense of Smell

The more olfactory receptor cells there are, and the greater the nasal capacity, the more olfactory data can be processed by the brain. We would naturally conclude, therefore, that dogs with elongated noses appear to be better suited for scent work. In fact, long-nosed breeds are most often chosen. This is not to say that a short-nosed dog cannot do scent work. It is merely to point out that the elongated nose has the advantage of drawing in more scent when sniffing.

With his long muzzle and amply sized nostrils, the German Shepherd Dog is prized for his scenting ability.

Brachycephalic, or short-faced, breeds have the facial structure that is least advantageous for tracking.

Environmental factors also influence a dog’s scenting ability. Conditions that cause the dog’s...