Scent Discrimination

This was originally published on my old blog, on 10-2-2010

There are many different ways to teach the competition Scent Discrimination exercise. How I do this is a combination of free shaping and chaining.

Behaviors needed: Retrieve on a verbal cue.

I check that the dog has no problem picking up the articles (metal and leather). I don’t spend much time on this, as I don’t want a strong article retrieve — yet! The dog needs to learn to locate my scent first. I do just enough to know that they retrieve them without a problem.

Touch Center of Scented Article

I scent this first article with just my hands (no food is placed on the article, except whatever treat scent happens to be on my hands). I place the article on the floor and C&T nose touches to the center bar. For avid retrievers, I hold the article until I have consistent, closed mouth touches and then move to the floor.

What behavior I want before moving on: 

  • Consistent closed mouth nose touches to the center bar, with both leather and metal articles.

Add Additional Articles

This is where the dog begins to associate my scent with the C&T.

Scent one metal or leather article (I consistently use the same number throughout). Have someone else touch another article (if no one is home, I use some dirty laundry and scent the other articles with that, using the opposite hand that I use to scent my article).

Now I place my scented and the other article on the floor fairly close together, clicking when the dogs’ nose touches my scented one. I toss the treat away, the dog comes back, nose touches and C&T again for touching my scented one. Repeat.  Add another article (I mix the leather and metal ones right from the start). I build up to 5 total articles, 2 leather, 2 metal and my scented one. I arrange them in a straight line.

Vary Location of Scented Article

When the dog is off eating the tossed treat, I start to place my scented ones in a different spot in relation to

the others each repetition. I use tongs to move the “unscented” article and my hand to move my scented article. I avoid placing an unscented one in the place my scented one was previously, to avoid any residual scent adding any confusion.

(The first dog I taught scent discrimination this way taught me to do this, she scented around the articles, looked at me and then indicated with a nose touch the floor where a scented article had previously been and the upper corner of the end of all the “unscented” articles where I had held them with just two fingers while putting them down!)

Empty space where scent article was previously
Move articles back on the floor to a “clean” spt

I do quite a few sessions at this level, doing them in different locations of my house. I vary my straight line arrangement, sometimes horizontal and sometimes vertical or diagonal. Only the dog knows how many repetitions will be needed for them to figure out that only the one that has your strong scent on it is the one that is clicked and treated.

The behaviors I am watching for before moving on:

  • I delay the click slightly and see that the dog expect to be clicked when she touches the scented one (might start, or look at me or…what does your dog do when they expect to be clicked?)
  • When the click is slightly delayed, they go on to another article and immediately go back to the scented one.
  • The dog skips nose touching the “unscented” articles, no longer relying on whether or not she is clicked to decide if it is that is not the one.
  • The dog clearly is using his nose, passing it over the unscented ones (thats not it) and only nose touching my scented one.

Teach My Scent is the Cue to Retrieve

Now that the dog is reliable at locating my scented article I add the retrieve cue.

Reduce the number of articles so that there are just 2, your scented article and one other. Space them farther apart so it is less likely that the dog will move on to the other article before you can get the verbal cue out. When the dogs nose is above the correct article, just before they will nose touch it, give your verbal retrieve cue. When the dog picks up the article, C&T. Yes, they most likely will drop the article — that’s ok at this point, we want to let them know that now, picking it up that one is what we want!

I gradually add a few more articles and repeat this with both metal and leather. Keep them spread out enough that it is easy to give the cue. After a number of repetitions, the dog will start to anticipate. You should see them start to open their mouth as they smell your scented article. Yay! When the dog is reliably picking up the correct article without the verbal retrieve cue, I stop clicking the pick up and instead cue front when they pick up the article. They quickly learn to anticpate that too, and then that can be dropped.

Still More to Do!

Now we have the basic behaviors in place, the dog goes to the articles, locates your scented one, picks it up and sits in front. Now I gradually start adding more articles and changing the arrangement, I make the straight line of articles not so straight or put them in a square or circle. Go slowly with this, it can’t be too reliable and your dog needs time to learn to check all of them. I only increase the number or change to a more challenging arrangement when the dog is 100% correct at the previous level. Ok…wait…what? What about the 80% rule?

The 80% Rule

This is a general guideline used to decide when to increase criteria. The purpose and reason for raising criteria when it is reliable 80% of the time is because that level of reliablility will be strong enough that the behavior won’t decline too much when made more difficult (the dog easily quits), but it is not so strong that it becomes too difficult to change it (the dog persists in doing the previous criteria). It is a very useful guideline (it isn’t exact, around 80% is good). However, we are now at a level where we aren’t going to change the behavior. Picking up our scented article and coming in to sit in front is not going to change. This I want to be as close to 100% as I can get it!!

So I continue to gradually add more articles and change the arrangement and location of the scented one. Whenever an element is added that is more difficult — distractions, distance, new location, I reduce the number of articles and/or distance from them.

Signs that it is too difficult and that you might be moving too fast:

  • The dog is going around the articles, but their mouth is not closed, they aren’t using their nose.
  • The dog picks up and puts down “unscented” articles.
  • The dog goes out to the area of the articles but looks off towards other things before starting
  • The dog just grabs one

What if the Dog Brings Back the Wrong Article?

I don’t change what I am doing, the dog comes to front and I take the article. I don’t give a treat or cue them to finish, just set up and do another repetition. I avoid doing anything because the dog might start to look to me to verify they are correct and drop the correct article if they don’t get that verification. So no helping them, no pointing it out or bringing them to the correct one. It can be hard to not give some indication with your facical expressions. I try to remember that I don’t know what the dog smelled, the scent could have drifted so that they did indeed smell the scent when they reached that article. Or they just made a mistake. If it happens more than once, than I need to change something so the dog will be right.

3 thoughts on “Scent Discrimination

  1. I have trained my dog to do scent discrimination. At home, he brings me the correct article roughly 98% – 99% of the time. I started to show him in utility and he had no trouble with this exercise until the judge had the steward put the articles near the high jump. This confused my dog, he sniffed the high jump, didn’t bring me an article. I retrained, putting a high jump near the articles (originally there was no jump). He learned to do the exercise again, brings me the correct article 99% of the time at home. I started to show again. He goes to the articles, but doesn’t even sniff them. Sometimes he brings me the second article, but naturally I want him to bring both articles. I bring him home, do the same exercise and he brings me the scented article right away. At home he goes briskly out, and even comes galloping back. At the show, he moves in slow motion for this exercise. What’s wrong here? Is it the scent that the steward puts on the articles? Could he be confused by the scents of other dogs on the floor? I’m confused.


    1. It is hard to know without knowing your dog or seeing it, there are so many things that can be happening. I have a family member scent my articles regularly, they don’t put them out but have touched them at some point before I go training.

      Do you ever have someone playing the judge during training? Having someone watching them is another difference that could be effecting it. I also will do them in different locations and places, up against walls or gates, near other objects, as many different things I can think of. The more distractions they can do it with the more fluent it becomes (whem making one part hard, I move in closer or make it easier for them to be right and then build the distance up again).

      Hope this gives you some ideas!


  2. Hi, Our 8 1/2 year old Bishon Frise, Maggie, has been home schooled in obedience all her life, just recently I enrolled her in obedience training with the purpose to socialize her with other dogs. We recently took her on vacation, since we were in a resort area the stores and most of the restaurants were dog friendly. She behaved so well that we decided to try to train her to be a service dog for my husband and that would allow us to travel more with her. My husband is diabetic and his blood sugar sometimes drops to the mid 40’s, he’s passed out before and it would really help if Maggie would let him know. Diabetics perspire when this happens and the scent is different from other times. Your article is helpful. I don’t quite understand how to get her to make the response we want. Just bringing the article (a piece of a T-shirt with the scent) is good but I want her to know to wake him up. She wakes us up for other reasons, when she hears something outside or when she needs to go out to potty. Anything you can add to your article will be helpful and appreciated.
    Laurie White


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