How Do Dogs Sniff Out Diseases?

A brown dog's nose pointed upward against a yellow background.

Dogs know the world through their exquisitely sensitive noses, and humans have been relying on dogs’ sense of smell to help with many different kinds of tasks (not always benevolent) for a long time. Dogs are trained to sniff out contraband at airports and international borders; dogs are instrumental in finding black truffles and other valuable wild mushrooms; and dogs are also trained to detect an imminent epileptic seizure before it occurs . Presently, scientists are developing training programs for dogs to sniff out COVID. In this July 2021 Discover Magazine report, science journalist Leslie Nemo analyzes the procedures that trainers and researchers follow to teach the necessary skills to the dogs. 

Read it here.


1. How do trainers and researchers manage to train a dog to detect a specific chemical that a person emits? Summarize the process briefly. How do they ensure that the dog is responding to the chemical and not the person? Explain the procedure. Is Nemo’s description of the process thorough and detailed enough? Why or why not? Point to examples from the article to support your conclusion.

2. As Nemo explains, not all dogs are up to the task of being a trained specialist in scent detection, and she compares the ones who are to “people who love fixing data errors in spreadsheets.” Is the comparison meaningful to you? Does it give you a good idea of the kinds of dogs that can be trained to be detection dogs? Why or why not? 

3. LET’S TALK. Dogs and humans have lived together and mutually benefited for many centuries. Some dogs are simply pets who have few or no “responsibilities” or chores to do and have no specialized training other than, perhaps, bladder and bowel control. Other dogs protect their homes and their humans, usually just by barking, which requires little or no additional training. Others still are working dogs that are trained to guide a visually impaired person, for example. Some learn to assist with herding livestock or similar activities. As Nemo describes, detection work is quite demanding and arduous, and requires lengthy and specialized training. What do you think about this new work role for dogs? Is it exploitative in any way? Is it just an ordinary expansion of the long-established relationship of mutual benefit? Should there be (or could there be) some kind of special compensation to dogs who perform such specialized work? Why or why not? Explore these questions with a few classmates, and remember to approach the conversation with an open mind (and heart). Don’t be surprised if you find yourself changing your opinion during the exchange.

4. AND NOW WRITE. As Nemo’s conclusion suggests, it’s not exactly news that dogs and other animals are able to gather information from their environments—information that is inaccessible to humans. For example, many species of animals in diverse parts of the world have been observed to change their behavior in the hours or moments before an earthquake. Choose an animal and do some research, either in the library, online, or by asking elders in your community. What kind of knowledge or sensory ability does the animal have that humans don’t have? Write an essay describing the animal and its ability, and document your sources. 

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