Cover Photo Credit: Nora Tenbrock with Hudson at SeaWorld Australia

It seems like in the training world there are many discussions about how to train specific behaviours. The training world is slowly moving towards focusing initially on more medical behaviours. One of the challenging behaviours is an mouth open behaviour. 

In my career I’ve only trained this behaviour 3 times. The last one I have yet to succeed completely, but I would like to share what with you what my techniques are. 

There are many reasons to train an mouth open behaviour. One of the main reasons is to check the health of the mouth. One classic sign of ill health in an animal is a loss of appetite. This could be caused by a number of factors but being able to check in the mouth for a wound, to get a good look at their teeth or even further in their throat. A mouth open behaviour is a very useful behaviour to have when you are in need to look inside an animals mouth.

Sydney and Me at Marineland of Canada in 2011

The first time I trained this behaviour was with a sealion in Canada. Here name was Sydney and she was trained for a variety of behaviours and understood the concept of the bridge very well. The goal was to have a mouth check without necessarily touching her face. This seemed like an easy goal but it wasn’t all that easy. She had learnt previously to bite hold of a ring and toss it in the air.

Scanning and Capturing

The training strategy I was going to use was scanning and capturing. I starting by asking her to go on her “seat”. I then showed her the ring and when I got closer to her she started to open her mouth, I bridged directly to show her what I wanted. Afterwards I asked again to see if she understood and I had the same result. It was just my first session so it was ok. 

Over time I conditioned her to, instead of biting the ring, open her mouth when I showed her the ring. From here I had to work on duration, I went with very tiny steps towards a duration of about 10 seconds. I would show her the ring, she would open her mouth and I would present the ring immediately again. She would now have her mouth open 2 times in a short period of time. Now I kept the ring for an extra couple of seconds, she would close her mouth a bit but open it again right away. This time she understood 2-3 seconds and I could extend easily to 5-10 seconds afterwards. I found that when she understands the first couple seconds afterwards it was a lot better and faster.

When this was set, I only had to change the ring into a hand signal instead and train the ring back to the criteria it had before.

You could replace the ring with food instead, which in some cases can be very effective. I’m not a big fan of using food because you can get frustration in the behaviour. Knowing the individual will help to determine if this strategy will work for you. The mouth open is the ‘easy part’ the challenge will be the duration, but this is the same with any medical behaviour.


A couple years ago I trained this behaviour again but this time I decided to go into protective contact. The animal I trained this behaviour with was a South African Fur Seal named Stella. She was a very hands on animal and I could have just as easily trained it in free contact. The training strategy I used this time was modelling. 

The animal would sit on the other side of the gate from me. I would ask her to target my hand. She was very stable on a target and her understanding of the bridge was very quick, which helped me to really pinpoint the moment I wanted to tell her what was correct. I started by trying to lift her upper lip and she accepted me doing this. Afterwards I added my nail in between her teeth. Me and her had a pretty good relationship so I wasn’t worried about my fingers. Slowly I added some pressure to open her mouth. Small approximations were taken and she seemed fine with it. The moment she started to open on her own I reinforced directly. When she understood the idea of opening her mouth on her own, it was just a matter of increasing duration. The signal we used was one finger on her nose and one on her chin.

“Teaching open mouth is one of my favourite behaviours to work on with trainers, because the timing of the marker is different than the way people often mark criterion. Mark too early and the animal learns to open its mouth just a little; mark too late and the animal learns to close its mouth too soon. Avoid training fish-mouth by marking motion, i.e., mark as the mouth is opening (not after) and the animal will learn to keep opening wider until it hears the marker. Then it’s a simple matter of delaying the marker approximation by approximation until you get a useful mouth open behaviour that is both opened wide and held long enough for a thorough inspection.” – S. G. Friedman, Ph. D.

Bactrian Camel being conditioned to open her mouth by modelling their lips. It is a lot easier when you have an animal with big lips because the movement to open a mouth is easy to reach.

At the same time, a colleague of mine trained this behaviour with another young fur seal. He decided to go a different direction. He had experience training this behaviour and decided to use modelling as well. His way of modelling was a bit different. His relationship was pretty good with the animal. His first step was adding a finger in the corner of her mouth. He had done this before with other individuals and it worked well but this time it went the other way around. He got her to open a little bit but then she started to close quickly. This resulted in a biting animal. 

We can say that using modelling has its advantages but also disadvantages as you can see. Small steps have to be taken and listening to the animal is very important. 

Chili learned a chin rest on my hand first and then I started to slowly open his mouth.

Recently I started to train this behaviour with a dog and a friend of mine. A beautiful Viszla, very well behaved and one of the sweetest dogs. I started with a chin target on my hand. Afterwards I added my other hand on top of his nose. He allowed me to do this pretty quickly. After this step I put a finger behind his teeth and he started to open his mouth very slowly. The bridge wasn’t established well at all, which was one of the mistakes I made. I was taking care of him as his owners were away for a while. My thinking was to train this quickly before they returned. 

One tip I can give is don’t train this behaviour under pressure. 

He’s not a big fan of the behaviour but he accepts me doing it. A good relationship is behind the two of us.

I discovered quickly that the dog wasn’t very good with me touching his mouth, so I decided to use the technique with the fur seal. Opening up by just pushing his upperjaw up through his front teeth and it worked. His chin target is pretty good now but I still have to help him with my finger. He does open directly when I touch. The dog is a hunting dog and knows the idea of stay. Wherever and whenever you ask this he will stay right there till you let him go again. I did the same for the mouth open what helped my duration drastically. Even though the mouth open is not 100%, through the chin rest checking his eyes and ears and applying medication is a lot easier now! 

As you can see there are a few ways to train an open mouth behaviour. Some people train this behaviour by having a target on the nose and one on the chin of the animal and try to get the animal to open their mouth by themselves. This behaviour requires a lot of patience and very good timing of your bridge. If you see that you aren’t making progress film yourself and pause the film where you bridge. This is how you discover that you might be bridging the downwards motion instead of upwards.

This is another mouth open behaviour but this time with a Hyena in Borås Zoo. You can see that the animal bites the fence on signal. This gives some more criteria to the behaviour and it makes it more black and white to the animal. A great way to set a good criteria to the animal and to have the animal opening its mouth at the same time.

A behaviour like this is very helpful for many reasons. This behaviour can be a base for many other behaviours, such as tubing, tooth cleaning, oral medication, saliva sampling etc. A behaviour like this is very helpful for many reasons.

It’s definitely a tricky behaviour but it’s worth it!


Peter is a passionate Animal Consultant that beside teaching you about Operant Conditioning makes sure you will go home motivated and inspired. Make sure you read his Bio!


PeterGiljam · May 31, 2021 at 08:54

Hi, When I worked in one of the zoos we worked with chimpanzees as well and trained a mouth open behaviour. Send us an email and we can help you if you like.

BRETT ALEXANDER MCDOWALL · May 31, 2021 at 04:00


PeterGiljam · March 11, 2019 at 17:15

Bill, Thats great thank you for your thoughts! I think you pinpoint out what is important “carefully approximations”!

Bill Winhall · March 11, 2019 at 14:51

I trained polar bears to open their mouth through protective contact. They knew the hand target behavior, with my hand open on the outside of the protective mesh. Then from the hand target I would ask “open” with SD first finger and thumb wide open with rest of hand closed. The bears didn’t know what I wanted, but they might relax their lips, maybe breath through their mouth and I would reinforce with verbal cue “OK”. The polar bears never got frustrated, understood to a certain extent the conditioning process/“training game”, and I would carefully bridge the mouth for being more relaxed, slightly more open (not allowing/reinforcing the bears biting on the mesh). Gradually they would open the mouth wider and hold it open longer through careful approximations.

Leave a Reply

Avatar placeholder

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.