READING YOUR DOG
ON ODOR

What a change of behavior is

A change of behavior, sometimes called a CoB, is a shift in how a dog moves and breathes when they catch odor. Each dog has their own version. For one dog it might be a faster tail. For another it is a sudden slow, deep sniff.

It is not a trick. It is something dogs do on their own when they reach the odor. Your job is to learn your dog's version, so you can tell the difference between a dog who is simply sniffing and a dog who has found what you are looking for.

A trained alert, such as a sit, is the final signal. The change of behavior comes first, and it often happens before the dog is close. For how to build a sit, read teaching a trained alert.

What to look for

These are common signs. No dog shows all of them.

• A head snap, where the head jerks toward a spot as the dog hits the scent
• A change in breathing, such as quick, sharp sniffs or a long, deep inhale
• The tail going stiff, high, or wagging faster
• A change in speed, like a sudden slowdown or a sudden rush
• Tight circles or back-and-forth movement, as the dog works the edges of the odor
• The body lowering or tightening
• A pause with the nose in one place
• Nose pushing against an object or crack

Every dog is different. A dog who always wags may not change their tail. A dog who always sniffs loudly may not change their breathing. You are looking for a change from your dog's usual search pattern.

Pay attention to small details too. Some dogs blink or lick their lips as they catch the scent. Some pull their ears forward. Some go quiet. The more detail you notice, the more accurate your read becomes.

The stages of an odor search

Many handlers describe a search in rough steps. The names vary, but the idea is simple.

Picking up the odor

The dog crosses the edge of the cloud. You may see the head snap or a tail change. This is the first sign.

Working the odor

The dog moves back and forth, narrowing to the area where it is strongest. The search gets tighter. See how scent moves for why they curve.

Source

The dog pins down the spot. Their nose is close to the source. They may freeze, stare, paw, or sit if trained.

Your task is to stay quiet through all three. Many handlers jump in too early. Give your dog time to work. If the dog leaves a spot and comes back, that is often the dog confirming.

Watch for traps

Reading a dog is partly a skill and partly a habit of honesty. A few traps catch most handlers.

Wishful thinking

Handlers who believe a hide is in a certain place often read their dog's behavior that way. A 2011 study in Animal Cognition by Lit and colleagues found that detection dogs alerted more often at locations where handlers believed target odor was, even when there was none. We do not need to overstate the result, but the lesson is useful: your expectations can change what you see, and can change what your dog does. Look at the dog, not at where you hope the odor is.

Mistaking stress for odor

Quick, scattered sniffing, sniffing at nothing, or pausing at a corner can be stress or interest in something else. Compare to your dog's usual pattern.

Pooling and drift

Odor can collect in corners or drift to places away from the source. A dog may show strong interest in a spot that is near, not on, the hide.

Contamination

If you or others have touched odor, it may be somewhere unexpected. See odor contamination.

How to practice

1. Film your searches. Watch the video slowly after. Note what the dog does just before the sit or freeze.
2. Practice with a helper. Have someone place a hide while you are out of the room. Call out when you think the dog has hit odor, then check the video.
3. Do blank searches. Search areas with no hide, and see what your dog's usual sniff looks like.
4. Keep a notebook. Write down what you saw each time, and what the dog did at the source.
5. Practice in different places. Your dog's change may look different on a windy day than in a quiet room.

Over time, you will see patterns. You may even spot the dog's change before they know it themselves.

When it does not work

Some dogs are quiet workers with very subtle changes. Others are so keen that every sniff looks like an alert. If you struggle to read your dog, a trainer can help. We can watch your searches and point out what we see. Our private lessons are suited for this.

If you need a clearer signal, a trained alert may help. Or you may find that your dog's change is clear once you slow down and watch. In trials, the handler calls the alert, so your read matters. Read about trial basics in your first scent work trial.

Above all, trust your dog and stay curious. A handler who watches closely and stays calm is giving the dog the best support there is.