Stacking the Negatives
Causing negative associations is extremely easy to do with muzzles. Misusing the muzzle, having a small muzzle, not training enough can all cause negative associations with the muzzle.
Common causes:
Only using in stressful situations will cause negative associations with the muzzle. If you only use the muzzle when you're going to the vet or car (or anywhere your dog needs the muzzle), then they will quickly associate the muzzle with stress. For example, when I started muzzling my dog, I would walk her without it, but the second we saw a dog off-leash, I would put it on as we walked past, and she would react. Then id take it off. In less than two weeks, she avoided the muzzle at all costs, and the second I got it on, she was looking for the dog stressing out.
Incorrectly fitted muzzles can also cause negative associations with the muzzle. This is self-explanatory but still needs to be here since it's a common issue. Using a muzzle that your dog finds uncomfortable can cause problems with the dog wearing any muzzle. Some dogs have no issues and learn to tolerate it, but others struggle more.
Wrong training methods will also cause negative associations with the muzzle. Rushing your dog, skipping steps, not muzzle training all together can cause issues with your dog. What is a problem will depend on the individual dog but making sure everything is suited to your dog-loving is the best way to make sure this doesn't happen.
How to stop it from happening:
In training (not just muzzle training), you need to make sure the positive situations outweigh the negative. If you have a bad situation, you need two more positive ones.
To apply this to muzzle training, if your dog only needs the muzzle once a week to go to group training (which could be stressful), you need to make sure you do two other training sessions in the muzzle that are fun and exciting.
Stacking negative upon negative situations is not good for any dog, so expecting your dog to be okay with the muzzle after using it in every negative situation they've had is entirely unfair.
Exceptions:
Sometimes you can't avoid negative situations, and that's okay. Suppose you have to go to the vet or use the muzzle in an emergency (which risks negative associations). In that case, it is completely fine to use and having to go back on some fun training is a much better option than risking a bite at the vet because they're not fully trained.
Training for ages but dog still hates it?
The first thing to check when muzzle training is that your muzzle fits correctly. If it’s too small or narrow, it can cause the dog to be uncomfortable. That would be unfair on the dog being asked to tolerate something uncomfortable and is likely a significant factor in why training is going forward.
If you do have a well-fit muzzle and you’re still having problems, what are you getting stuck on? Have you tried going back a few steps? Are you asking too much of your dog? Are you rushing it? Is your dog confused?
Usually, going back a few steps can help with a dog being stuck on something. Gradually adding duration between rewards/movement etc., instead of expecting them to move 2ft straight away, as well as making sure you’ve worked on training long enough.
Working out what the issue is and changing what you're doing is the best way to do this; if you can't pinpoint the problem, change what you're doing and go back to the start.
FAQ Muzzle Training
Train Without A Muzzle
You can ‘muzzle train’ your dog before they have a muzzle. Getting your dog comfortable with placing their face/nose into something works just as well and greatly helps when transferring to a muzzle. Start by finding something they can comfortably place their nose/head in, that they can't get to normally (don't entice to eat out of a container you're going to leave on a bench that they could take and chew)
You can start by offering a few treats in the container to eat out of, continue dropping more in as they go.
Once they’re comfortable eating out of it, you can start adding a command while luring or free shaping, depending on what works for your dog. When they place their face in, you can say ‘yes’ and then reward, either by dropping food in or giving it to them.
When they place their face on the command, you can start asking for some duration. This isn’t as needed until you get the much since they will be much better ventilated.
Once they’re comfortable with all of the above, you can start by moving the container around, either in your hand or on the ground and ask the same thing, this creates movement, and you can turn it into a game.
All this will significantly help when getting a muzzle. Transferring over to a muzzle should be simple. Some dogs may drop back a few steps, which is entirely normal if new things make them unsure.