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Project Summary

Difficulty	4  –  6
Time required	Very Long (several weeks to months)
Prerequisites	Comfortable around dogs and knowledgeable in their treatment and care
Material Availability	Readily available
Cost	Low ($20 - $50)
Safety	Requires adult supervision

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Objective

The goal of this project is to discover what types of smells are most interesting to dogs.

Introduction

Click here to watch a video of this investigation, produced by DragonflyTV and presented by pbskidsgo.org

The video shows two lucky students, Paige and Nick, who were fortunate enough to study animal behavior by getting to do experiments at their local zoo. Paige and Nick were interested in exploring which types of scents animals found most enticing. With assistance from the zookeepers, they were able to test the smell preferences of both wolves and mountain lions as the animals roamed their enclosures. Few people have direct access to wild animals or have zookeepers to help with setting up science projects, but you can still gather some great experimental data about animal scent preferences in this project using a more accessible and tame setting.

In these experiments, your favorite canine (the family dog) becomes your primary subject. You'll set up several smell tests, first for your dog and then for other local canine "volunteers", to see just how sensitive and selective a dog's sense of smell can be. You'll examine the dogs' responses to various types of odors from food, people, or animals. These experiments will require careful observations on your part and a keen eye to pick up subtle signals from your pet to determine which scents rank high or low according to his/her nose.

Begin by checking out the video to see how Paige and Nick set up their experiments and decided on what observations to make of the zoo animals. Then read on to find out how to organize your own study to investigate the fascinating perspective of the world as perceived through a dog's busy nose.

Before beginning your project, do a little research into the amazingly sensitive sense of smell (olfaction) canines possess. Also investigate how animal behavior studies are usually done so you can run your experiments like experts in the field. You will find a list of search terms and basic questions in the next section along with a bibliography of a few websites to get your started.

Learning about the structure of a dog's nose and snout, in particular, will help you better understand how man's best friend can detect odors up to several miles away and more than a 1,000-fold better than we can. You'll find, for example, that some dogs can have as many as 300 million specialized scent-detecting organs called chemoreceptors lining their nasal cavity; people have a paltry five million at most. Also, those endearing wet doggie noses and constant sniffing habits are additional adaptations that enhance a dog's sense of smell. The moisture on and within a dog's nasal passages improves absorption of air-borne molecules, and the repeated sniffing ensures that lots of air circulates over the receptor-laden membranes lining the canine nose.

Dogs also have a highly developed Jacobson's organ located above the roof of the mouth that specifically picks up body scents or pheromones. Signals from both the Jacobson's organ and the chemoreceptors of the nasal passages are channeled to regions of the brain for recognition and interpretation. The two primary centers for smell in the brain are called the olfactory lobes. These can be up to fourteen times larger in some dogs than in humans, especially in breeds like bloodhounds that are skilled at hunting or tracking. No wonder some canine experts humorously refer to bloodhounds as "noses with a dog attached."

Your first goal in this project is to find out what scents seem most interesting to that super nose attached to your dog. Then you will test these scents using dog "volunteers" you recruit from pet owners in your area. Once you set up the tests and collect your data, you might be surprised at how differently the world appears when viewed through the sensitive nose of a canine. Perhaps then you'll gain an even greater appreciation for just how specially super-powered yours, and every dog, truly is.

Terms, Concepts and Questions to Start Background Research

To do this project, you should do research that enables you to understand the following terms and concepts:

• Smell (olfaction) sense of dogs
• Chemoreceptors
• Olfactory lobe
• Smell tests
• Animal behavior

Questions

• Describe how a dog's nose, mouth, head, and brain are especially adapted for a keen sense of smell.
• How does a dog's sense of smell compare with a human and with other animals? Describe the differences between various breeds of dogs in their ability to smell.
• Describe how animal behavioral scientists conduct tests to determine an animal's intelligence, behavior, and taste or smell preferences.
• List several ways a canine (dog or wolf) relies on the sense of smell for survival and awareness.

Bibliography

Here are some websites you might want to check out as you start your research:

• Introduction to interpreting dog behavior and descriptions of dogs' various senses:
  Dibra, B. and Crenshaw, M., 1999. Excerpt from "Chapter Two: DogSpeak For Beginners," Dogspeak: How to Learn It, and Use It to Have a Happy, Healthy, Well-Behaved Dog, Simon & Schuster, Inc. [accessed September 9, 2007] http://www.simonsays.com/content/book.cfm?tab=1&pid=410564&agid=2.
• How a dog's anatomy is adapted for smell:
  Correa, J., 2005. "The Dog's Sense of Smell," Alabama A & M University [accessed August 5, 2007] http://www.aces.edu/pubs/docs/U/UNP-0066/.
• How the canine nose works and is used in hunting and tracking:
  Purina, no date. "Sporting Library," Purina ProPlan web site [accessed August 5, 2007] http://www.proplan.com/sportingdog/Pro%20Plan%20Sporting%20Dogs%20-%20Tracking%20a%20Dog's%20Keen%20Sense%20of%20Smell.htm.
• Some interesting facts and statistics about dogs' ability to smell:
  Wiley Publishing, 2007. "Understanding a Dog's Sense of Smell," adapted from Understanding Your Dog for Dummies [accessed August 5, 2007] http://www.dummies.com/WileyCDA/DummiesArticle/id-5324.html.
• How dogs like bloodhounds are especially adapted for tracking:
  PBS, 2007. "Underdogs. Making Sense of Bloodhounds," Nature Series, PBS, Thirteen/WNET New York [accessed September 9, 2007] http://www.pbs.org/wnet/nature/underdogs/bloodhounds.html.
• Website describing how to do many types of tests with pets:
  BBC, 2004. "Test Your Pet, BBC. Science and Nature 9 [accessed September 9, 2007] http://www.bbc.co.uk/nature/animals/pets/testyourpet/tests/static/dog_2.shtml.
• An example of a published study on dog behavior:
  Alhen, A. et al, 2004. "Paw Preference Correlates to Task Performance in Dogs," pdf file [accessed September 9, 2007] http://www.cs.vu.nl/en/sec/ai/asr/Projects/dog-cognition/cogsci649-alphen.pdf.
• The idea for this project came from this DragonflyTV podcast:
  TPT, 2006. "Animal Scents by Paige and Nick," DragonflyTV, Twin Cities Public Television [accessed August 4, 2007] http://pbskids.org/dragonflytv/show/animalscents.html.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

• One assistant to help you run your tests (timer/camera person)
• Large room with no furniture
• Separate "waiting room" or outdoor area for the dogs
• At least ten adult dogs with their owners (see guidelines below for using dogs in experiments); It will take several weeks to recruit the dogs.
• Doggie treats and water pans
• Disposable gloves
• Clean plastic containers with lids that have multiple holes punched into them
• Items to use in smell tests: select three items for each test from the lists below. (You could also try one or two additional items of your choice).
  • Test 1. Fruits (fresh cut pieces of banana, oranges, apples, pineapple, strawberries, or a mix of several fruits)
  • Test 2. Meats (fresh hamburger, hot dog, raw chicken, raw beef, raw pork; same types of meat, but 3-4 days old; a mix of meats; doggie treats)
  • Test 3. Animal/People scents (sock or scarf recently worn by the dog's owner, one of the dog's own soft toys/ball, dried dog poop, wad of newspaper soiled with dog urine)
• Note book
• Pen or pencil
• Marking pen
• Spray bottle with disinfectant to clean up after a dog, if necessary
• Paper towels
• Optional: Video camera with a time and date stamp, tripod
• Special notes about using dogs in experiments:
  1. Make sure an adult is present when you test any dog.
  2. Recruit dogs for your study by contacting dog owners in your neighborhood, at a local dog park, or through your veterinarian.
  3. You will need at least ten dog "volunteers," but more would be better. For information on how many volunteers are needed in a study, see the Science Buddies guidelines: Sample Size: How Many Survey Participants Do I Need?.
  4. For each dog you test, get the dog owner's name, phone number/email address, as well as the dog's name, age, gender, breed, and number of years with the current owner.
  5. The dog owners must participate in the study by controlling their dog before, during and after test trials.
  6. Never force a dog to participate. If the dog is unwilling to take part, try again later.
  7. Don't use puppies for the experiments. They don't have the maturity or training to follow instructions from their owners.
  8. Do not include chocolate, grapes, raisins, onions, or garlic in your tests as these foods are toxic to dogs.

Experimental Procedure

Preliminary Instructions

1. Recruit your dog "volunteers." See notes above on finding dogs for your study and the ideal number of dogs to use.
2. Inform the dog owners of the type of tests that will be done, and the day, time, and place of your testing. Depending on the number of dogs in your experiment, you may have to schedule your tests on more than one day.
3. Each test involves three trials, and you should change the order of the test containers between each trial. That way you will know if the dog is really attracted to the smell within the container and not just exploring in the same direction each time.
4. Decide on at least six observations you want to make in each test to determine how interested a dog is in each of the scents. Here are some suggestions:
   • First Choice (dog goes to this container first)
   • Lingering (dog stays or interacts with this container for the most time)
   • Repeated Visits (dog comes back to this container most frequently)
   • Sniffing (dog keeps sniffing at the container after the initial sniff of all containers)
   • Physical Interaction (dog paws or chews at the container)
   • Vocalization (dog whines or barks at the container)
   • Avoids (dog shows no or little interest in the container)
   • Marking (dog urinates on the container or the area around the container)
   • Other
5. Prepare data tables similar to the example below to check off your observations for each dog in each test.

   Data Table Example

   OBSERVATIONS: Experiment 1, Test One (Fruit Scents)
   Fruit Sample:	Container A			Container B			Container C
   Trial Number:	1	2	3	1	2	3	1	2	3
   First Choice
   Lingering
   Repeat Visits
   Sniffing
   Physical Interaction
   Vocalization
   Avoids
   Marking
   Other

6. The day of your tests, prepare your smell test samples. Use disposable gloves to cut up or handle the samples so that you don't get any of your scent on the items. Place the samples into individual plastic containers. Be sure the lids have multiple holes punched into them before you close the containers. Label each container in large print using a black marker (ie. "Fruit A," "Fruit B," Fruit C," "Meat A," "Meat B," etc.).
7. Note: You can keep the test containers refrigerated and tightly wrapped in plastic bags until you are ready to run your tests, but be sure they sit out at room temperature for at least 30 minutes before starting the tests with the dogs.
8. Set up the video and tripod, if you are using a camera to record the tests.

Experiment 1. Determining favorite scents of your dog

1. In this experiment, you will determine your dog's favorite scents of fruit, meats, and animals/people. These favorites will become the three test samples for your dog and the other dogs in Experiment 2.
2. Prepare three data tables similar to the example above to check off your observations for Tests 1, 2, and 3.
3. Note: Your dog will do three trials for each test in this Experiment. If your dog seems to be getting a little tired or bored after the first or second tests, you can do the remaining test(s) on another day.
4. Test 1. Fruit: Using disposal gloves, set out the three labeled fruit containers, A, B, and C. Space them as far apart as possible in the room, but equal distances from where the dog will be sitting before the start of the test.
5. Bring your dog into the room. Have your dog sit as far away from the containers as possible. Then, on your or their owner's command, let the dog go to explore the room and containers.
6. Start the stop watch, and let your dog freely interact with the containers for 1 minute. Note: If your dog needs more than one minute to explore the containers, you can increase the time, but be sure to use the same time limit for all experiments.
7. Film the test or record your observations of your dog's behavior in your data table.
8. After 1 minute, call your dog back and put him/her back into the waiting area.
9. Set the same containers up again, but change their order so the sample that was in the middle is now on either the right or left.
10. Bring your dog back into the room, and repeat the one minute trial with the fruit containers in the new order. Film the test or record your observations in your notebook.
11. After the second trial, take your dog out to the waiting area for another few minutes while you rearrange the containers one last time in another order.
12. Bring your dog back in, and repeat the one minute trial for the last time in this test. Film the test or record your observations in your notebook.
13. Test 2. Meats: Repeat the procedure using three containers of different types of meats. Note: be sure to put on new disposable gloves before setting out the meat containers.
14. Test 3. Animal/People Scents: Repeat the procedure using the three containers of different types of animal/people samples. Note: be sure to put on new disposable gloves before setting out the animal/people scent containers.
15. Analyze your results to determine which fruit, meat, and animal scent your dog preferred.

Experiment 2. Determining favorite scents of your dog and volunteer dogs

1. Label and prepare clean plastic containers for the three samples (A = fruit, B = meat, and C = animal/people) that were your dog's favorite fruit, meat, and animal/people scents from Experiment 1.
2. Prepare one data table for each dog. List the same observation categories you used in Experiment 1.
3. Prepare your samples, and set up the the containers in the room as you did in Experiment 1.
4. Test one dog at a time.
5. Ask the owner to bring their dog on a leash. At the owners' command, let the dog free to explore the room and containers.
6. Start the stopwatch, and make your observations for 1 minute while the dog reacts to the scents in the containers.
7. Have the owner take the dog out of the room for a few minutes while you rearrange the order of the containers.
8. Repeat the test two more times, taking the dog out and changing the order of the containers each time.

Analyzing Your Data

1. For each dog in Experiment 2, determine which scent was their favorite (fruit, meat, or animal/people scent).
2. Total the number of dogs that preferred each scent.
3. Which scent was most popular? Did all dogs favor the same scent?
4. Were the type of reactions to each scent the same for all dogs? If not, which were the predominant reactions for each scent in the group of dogs?
5. Can you relate your findings to canine behavior in the wild?
6. For help with data analysis and setting up tables, see Data Analysis & Graphs.
7. For a guide on how to summarize your results and write conclusions based on your data, see Conclusions.

Variations

• Change the Scent Options: Instead of using three different kinds of scents (fruit, meats, and animal/people scents) in Experiment 2, select just one category and use three samples within that category to fine tune your results. For example, do an experiment to find out which kind of meat scents or which kind of animal/people scents dogs prefer. Alternatively, try your study with a different set of scents altogether. Substitute vegetables or spices for fruit, for instance, or use some other category that you think the dogs would find appealing.
• Influence of Hunger: Does it make a difference if the dogs are hungry when they participate in the experiments? Do the experiments at two different times, when the dogs have been recently fed and when the dogs haven't been fed for at least six to eight hours.
• Influence of Dog Gender or Breed: Some studies of paw preference in dogs found that female dogs tended to use their right paw most often and male dogs tended to use their left paw. Repeat Experiment 2 with ten female and ten male dogs to see if you find any gender bias for scent preferences. Or repeat the experiments using ten dogs of one breed and ten dogs of another breed.
• Try This with Kitty: Do these experiments with cats instead of dogs. Do cats have similar responses to the same scents? What type of behaviors do cats demonstrate when they are interested in a scent? How do these behaviors compare to dogs?
• For another Science Buddies project related to testing dogs' intelligence, see Dog Smarts: What's Going on Behind Those Puppy-Dog Eyes?.
• For another Science Buddies animal project, see Paw Preference in Pets.

• For more science project ideas in this area of science, see Mammalian Biology Project Ideas.

Credits

Darlene E. Jenkins, Ph.D.

Sources

The idea for this project came from this DragonflyTV podcast:

• TPT, 2006. "Animal Scents by Paige and Nick," Twin Cities Public Television http://pbskids.org/dragonflytv/show/animalscents.html.

Last edit date: 2008-06-18 12:00:00

Career Focus

If you like this project, you might want to think about career opportunities in Mammalian Biology.

Veterinarians help prevent, diagnose and treat health problems in a wide variety of animals. Regardless of whether the animal is a family pet, a prize-winning race horse, a dairy cow, a circus lion, or seal in a zoo, its healthcare depends on veterinarians. Learn more about this career: Veterinarian.