Canines

The Original Biosensors

Lauryn E. DeGreeff, Craig A. Schultz, Lauryn E. DeGreeff, Craig A. Schultz

• Verlag: Jenny Stanford Publishing
• Jahr: 2022
• ISBN:
  9781000534610
• Auflage: 1
• Thema: Scienze fisiche
• Thema: Chimica analitica

Detection canines have been utilized throughout the world for over a century, and while numerous attempts have been made to replicate the canine's ability to detect substances by mechanical means, none has been as successful. The olfactory system is a highly intricate and sophisticated design for chemical sensing, and the olfactory capacity of many animals, including canines, is considered unmatched by machine due to not only their great sensitivity and superior selectivity but also their trainability and mobility. These unique features have led to the use of such animals as "whole-animal" biosensors.

Amplifying the benefits and diminishing the limitations of detectioncanines' interdisciplinary research is crucial to understanding canine olfaction and detection and enhancing this powerful and complex detector. The past 50 years have produced vast advancements in animal behavior/training technology to develop canines into more proficient and reliable sensors, while scientific research has provided tremendous support to help practitioners better understand how to utilize this powerful sensor. This book assembles a diverse group of authors with expertise in a variety of fields relating to detection canines and the chemical sensing industry, including both research and operational perspectives ondetection canines. It illustrates how science enhances our understanding of how canines areemployed for solving some of the world's leading detection challenges.

Section 1 A Dog’s World: Chemical Sensing Through Olfaction

Chapter 1 Introduction: Canine, the Original Biosensor

Lauryn E. DeGreeff

International Forensic Research Institute, Global Forensic & Justice Center, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA

[email protected]

1.1 Chemical Sensing through Olfaction

1.1.1 The Canine Biosensor

Sensing is how an organism reacts and interacts with the outside world, for activities such as communication, self-location, location of food or a mate, and identifying danger. Accordingly, a biosensor is an analytical device that exploits this natural capability by incorporating a biologically derived method for chemical sensing by converting biological signals into measurable responses. Electronic noses or other mechanisms of artificial olfaction, including those with bio-inspired design, are attractive as they are often smaller, more affordable, easier to use, have a longer duty cycle, and have lesser consumable and power requirements than larger laboratory instrumentation [1]. For this reason, they are used in a diverse number of fields from explosives detection to medical diagnostics, though most commonly utilized in food and fragrance industries, as well as for toxic chemical detection [2].

One example of chemical sensing equipment, the olfactory system, is rarely, if ever, rivaled by others. The olfactory capacity of many animals, to include canines, is frequently considered unmatched by machine, and this, with their trainability and mobility, has led to the use of such animals as “whole-animal” biosensors [1, 3]. The olfactory system in a canine, or any other organism is, in essence, composed of comparable component parts and functions similarly to chemical sensors or vapor detection instrumentation. In mammals, odor delivery occurs when odor is inhales into the nasal cavity. The canine nasal cavity has the further advantage of odorant separation and preconcentration in the mucous membrane. As odorants dissolve into the mucous, they are delivered to olfactory receptor neurons, which act as an array of volatile organic compound (VOC) sensors. The unique response pattern of the olfactory nerves to a given analytes is processed by the olfactory bulb in the brain where perceptions of distinct odors are formed and a response to said odor is initiated. Furthermore, the olfactory system is capable of classification of new odorants based on previous familiarity with a chemically similar odor, allowing for categorization or generalization of odors based on feature similarity [4, 5].

To amplify the benefits and diminish the limitations of canine detectors, and thus maximize sensitivity while minimizing false positives, interdisciplinary research is crucial to understanding canine olfaction and detection and enhancing this powerful and complex detector. For example, neuroscientists study mechanisms of olfaction in the brain and the action of olfactory receptors. Physicists and engineers have modeled odor movement and canine sniffing dynamics. Animal behaviorists and veterinarians study canine cognition, learning, training methods, the effects of environmental, mental, and physical stressors, breeding and husbandry practices. Chemists make measurements to determine the quality and quantity of the odor to be detected. Finally, practitioners compile this wealth of information to develop protocols for training and testing with the intent of producing a highly proficient detector. Many of these topics are addressed in detail in chapters throughout this book.

1.1.2 A Brief History of Canines as Detectors

Humans have had some knowledge of the canine’s superior olfactory prowess, among other valuable attributes, from the time dogs were domesticated. From early times, canines were utilized for the benefit of humans, and have been further selectively bred for favorable traits that enhance their ability to carry out their given job [6, 7]. An early example of working dogs is told through Egyptian hieroglyphics, where canines were used as hunter companions and as messengers and guards for army encampments [8]. Other early documented uses of canines by Ancient Greeks, Native Americans, and even Napoleon, were most commonly for protection and carrying supplies [9], although early Romans also used canines for security, hunting, war, and tracking humans [10, 11], and in the Middle Ages, canines were given armor and used to defend convoys [9]. The first known instance of canines used in policing was in the early 14th century where the French police used guard dogs at naval installations and docks at St. Malo. They continued to use canines in this manner until the late 1700s [12].

The first well-documented use of canines for scent detection (other than hunting) is the story of Barry der Menschenretter (Fig. 1.1), a Saint Bernard who is thought to be one of the first dogs used by humans for air scenting. Barry lived with monks at a hospice in the treacherous Saint Bernard Pass in the Swiss Alps from 1800–1812. Barry, and other Saint Bernards, living at the monastery were sent to search the snow for lost and buried travelers along the pass. Barry was credited for saving more than 40 lives himself, and all of the rescue dogs were said to have saved more than 2000 stranded travelers [11, 13].

Figure 1.1 Image of Barry carrying a child to safety (this photographic reproduction is in the public domain).

1.1.2.1 Early uses of canines by law enforcement

The first modern use of canines for scent detection, tracking and searching, was for the purpose of law enforcement in the late 1800s in Europe. It is often recounted that in the 1880s Scotland Yard in London used bloodhounds in police work. In fact, it is frequently reported that these bloodhounds were used to locate Jack the Ripper; however, there is evidence that due to cultural and practical challenges at the time, the bloodhounds were never used in this particular case. Prior to this time, English sportsmen revered purebred dogs, including bloodhounds, for their ability to track prey in the field. It was not until the manhunt for Jack the Ripper, that police appropriation of canines for scent detection moved this knowledge from the countryside to an urban environment, extending the canine scenting capabilities to investigation and evidence gathering. In 1888, as the serial killer was in the midst of terrorizing London, the police chief began tests of two bloodhounds, Barnaby and Burgho, and found that they were capable of following the trail of strangers through West London, even when others had crossed the trails. After passing these tests, Barnaby and Burgho were retained awaiting the next murder. Four weeks later, when this time came, the animals were not deployed for unknown reasons. Nevertheless, the preparations for the use of bloodhounds in the case was important in demonstrating the value of canines in following scent for the purpose of law enforcement investigations [14].

Police in Paris and Germany in the 1890s indeed employed canines to control gang violence, and by the early 1900s canine trailing and scent discrimination began to be employed throughout Europe [15]. Scent identification lineups were adopted in the Netherlands and Germany as early as 1903 [16]. Also at that time, Ghent, Belgium was considered the world leader in police dog utilization. Ghent was the first school to train the canine and handler as one using primarily Belgian Sheep Dogs and Wolfhounds [12].

The practices developed in Ghent spread to the United States when, in 1907, the New York City police commissioner, George Wakefiled, was sent to Ghent to study the Belgian methods, and then returned to New York with canines to be used by New York City Police Department (NYPD). By 1911, the NYPD had six patrol dogs used to search houses and track, chase, and capture suspects. Also in 1910, neighboring jurisdictions in New Jersey and Connecticut began training search dogs. The use of canine teams only lasted a short time due to limited success, poor training, and high costs of maintenance [12].

Also in the early 1900s, in Germany, the first formalized experiments to examine breeding, training, and utilization of canines for police were carried out, concluding that the German Shepherd, followed by the Doberman Pinscher, were the most apt breeds for the job. Based on this research and successful utilization of police canines across Germany, the Greenheide School for basic obedience, tracking, and searching for police dogs was established in Greenheide, Germany in 1920 [15]. From the success of the Greenheide School, the British Home Office Standing Advisory Committee on Patrol Dogs outlined the London Plan, later to be adopted by the United States and other parts of Europe. The London Plan was recognized as the most comprehensive and effective police canine training school. The 14-week training program for canine/ handler teams included training in obedience, tracking, attack, and search. In 1954 a committee was brought together to coordinate the breeding, supply, and training of police dogs across the United Kingdom, and by the late 1950s, approximately 300 police dogs in the London Metropolitan Police had been trained through this program [12, 17].

1.1.2.2 Early uses of canines in war

In addition to policing, humans found an early use for canines as war dogs. Ancient and early war dogs were valued for their strength and aggression as they were utilized to find, attack, and destroy the enemy and as sentries, or guard dogs [9, 18]. In World War I Germany was said to have trained as many as 30,000 canines for combat, used for locating wounded soldiers (Fig. 1.2), sentry, laying telegraph wires, carrying supplies, and acting as decoys to uncover enemy location. Of American World War I fame was Sgt. Stubby (Fig. 1.3), a stray Bull Terrier-Boxer mix that inadvertently wandered into an Army Infantry training camp, only to become the sole American dog to serve overseas during WWI. With no formal training, he was used to seek out and comfort wounded soldiers, and warn troops of incoming fire and mustard gas attacks [18].

Figure 1.2 Dogs of the German Medical Corp, trained to check vital signs of stranded soldiers (photo in public domain; obtained from publicdomainclip-art.blogspot.com).

Figure 1.3 Sergeant Stubby in uniform with military decorations (this photograph is in the public domain).

In the 1930s, as warfighting technology advanced prior to World War II, canines were added to the U.S. military arsenal [18]. The American K-9 Corp formalized manuals and instruction on animal care and training for sentry, attack, messenger, casualty, and scout dogs for combat. Figure 1.4 gives an example of search instruction given in the K-9 Corp training manual [9]. The K-9 Corp was decommissioned in 1958 with remaining dogs going to the Air Force Military Working Dog Agency at Lackland Air Force Base [18].

Figure 1.4 Example from America K-9 Corp training manual. Figure courtesy of HathiTrust (retrieved from https://babel.hathitrust.org/cgi/pt?id=uc1.b3245385&view=1up&seq=7) [9].

Across the world, canines were used on an even greater scale in WWII than W...