Detector dog handlers have been known to say things like, “I can read my dog”, “My dog knows it’s there”, “My dog’s behavior tells me it is there”, “I know by the JNDs it’s there”, “ I can read my dogs behavioral change and I know the odor is there”, “I am the only one who can read my dog”, “I know what my dog is thinking”, “ I know when he is in the scent cone”, he showed interest, et cetera. Some handlers say the dog indicates by a specific sniffing pattern. Are they just repeating what they were taught? If not, where do they get this notion? In initial training and subsequent training the only time they reward (reinforce) their dog is when the dog makes the definitive defined final response. Then and only then can the trainer verify the dog has detected and responded to a specific target odor.  The dog is rewarded for that response and no other. This is the method used to teach the dog to discriminate target odors from non-target odors.


            The olfactory searching behavior by a dog is innate. The behavior of searching for an odor of biological interest or significance has been reinforced since the dog was born. Behavior modification is required to insert stimuli to cue the dog to make those searching behaviors to cues in order to detect specific target odors. Those target odors have no biological significance to the dog. The dog will make searching behaviors in the presence of non-target odors of biological significance that duplicate the behaviors used to search for target odors. Again the defined final response in a properly trained dog distinguishes the difference.

The first thing one must do before conducting the first training trial to train a detector dog is to decide what specific response   the dog must make in order to determine if it is responding correctly to a selected target odor. That response is referred to as the defined final response!  The handler or trainer must be able to articulate that specific response to anyone not in the dog training profession.  That specific response is the only response you reward with the selected primary reinforcement. By doing this, the dog learns to make this specific response in the presence of the target odor. Withholding the primary reward when that specific response is not made to target odors or is made to non-target odors allows one to teach the dog to discriminate target odors from non-target odors. All the other searching responses (referred to as orienting , scanning or, casting,  responses) exhibited prior to the final response are indeed important in that you teach the dog to search until the dog locates the source of the target odor or gets as near to it as it can. The dog will also make all or some of those responses on any non-target odor of interest, to the dog, in the area searched. Once the dog has learned the task, the only way the dog handler will know when a target odor is present is when the dog makes the defined final response.  The handler and trainer must have a complete knowledge and application of the concept of extinction.


            Orienting responses (also called preparatory response, scanning, and casting) include but are not limited to, increased sniffing, hyper- activity, head turns, tail wagging, slowing down, speeding up, closing its’ mouth, doubling back, breathing pattern changes, lifting its’ nose in the air, etc. In initial training and in subsequent proficiency training you never reward those responses (unless your reward timing is at fault) in order to teach the dog the defined final response .  You only reward the defined final response  when it is made to the target odor. You can eliminate (extinguish) irrelevant responses and responses to non-target odors by withholding the reward or as some trainers do, apply physical correction.  When and if the primary reward is strong enough to control the dog’s behavior you teach the dog to discriminate the difference between target odors and non-target odors. A thorough understanding of the concept and the use of controlled negative testing will provide proof the dog has indeed learned to discriminate and respond properly to a series of target odors and not to non- target odors.  


            If the dog does not make the defined final response   sometime during a search, the target odor is either not present or the dog or handler made an error. Dogs do respond when no target odor is present. They also fail to respond when a target odor is present.  The handler may assume any response other than the defined final response verifies the presence of a target odor.  At this point the handler is guilty of interpretation, supposition, or speculation.  The dog has the olfactory sensing system (nose) and the final decision as to the presence or absence of a target odor is up to the dog  not the handler . A well-trained detector dog (this term is nebulous and has not been defined by the courts) will only respond to the target odors it has been properly trained to detect. That dog will emit the defined final response it has been trained to make to a target odor at a predetermined rate of accuracy.


            Educated guesses based upon the handler’s knowledge of their dog’s training and past performance are nothing more than educated guesses when their dog fails to make the defined final response during a specific search. This holds true regardless of the response the dog was taught to make when it discriminates the presence of a target odor.  When a dog makes the defined final response and no controlled drugs are found on physical search one must rely on forensic chemical analysis to justify the accuracy of the dog.