One sure way to fail at dog training is to allow yourself to get angry at the dog. Anger tends to cloud our judgement and make us poor, heavy handed trainers.  In addition to it’s effect on us, anger also has a profound effect on our student, the dog.

Humans have a substance that is secreted from the pores of our skin whenever we are under any kind of emotional stress.  This substance is called butyric acid.  This substance can be detected by dogs at concentrations as low as 10 ppb (parts per billion)!
Trainers and authors Milo Pearsall and Hugo Verbruggen MD put this into perspective with this analogy: 
One of the substances released by human perspiration is butyric acid.  If one gram of this chemical (one small drop in the bottom of a teaspoon) were to be spread throughout a ten story building, a person could smell it at the window, only at the moment of release.  If this same amount were spread over the entire city of Philadelphia, a dog could smell it anywhere, even up to an altitude of 300 feet.
This example shows how sensitive dogs are to butyric acid and it lends credence to the old adage that “dogs can smell fear”.
When you get angry or irritated, even before you actually notice that you are perspiring; your pores have excreted enough of this substance to be easily detected by your dog.  Not only does he detect the scent, but it’s so powerful that it’s like the olfactory equivalent of a full volley of Fourth of July fireworks going off all around you.
There is no question that your dog knows when you are angry or under any other form of emotional stress.  The wild card hits the table in the form of your dog’s reaction to your emotional stress.  Dogs react differently to your anger according to their own personal traits.  One of the most common reactions is for the dog to simply fold or give up.  This is the usual reaction in dogs that have a soft or subordinate personality.  Other dogs that possess more dominant traits may react to your anger with aggression of their own.
Regardless of the dog’s reaction, it is counterproductive to training and, if allowed to continue, these reactions can spiral into a vicious circle with your anger feeding the dog’s reaction causing more irritation on your part and on and on….
So, how do we avoid these kinds of situations?  We hear so often today about things like “anger management” and we hear of people talking about “controlling their anger”.  Is anger management useful for us as dog trainers?  Unfortunately, no, managing or controlling your anger doesn’t really help.  Once you’ve allowed the emotion to manifest in your mind, no amount of “anger management” or control can prevent the excretion of butyric acid from your pores.
This brings us to one of the most important lessons that I have learned from dogs as I’ve worked with them: Don’t Get Angry.  See how this is different than anger management or controlling your anger?  If you just avoid the emotion entirely, there’s nothing to manage, nothing that needs to be controlled.  I know it seems pretty obvious but at the same time I can hear you asking, “sure Jon, great advice, but how do you prevent yourself from getting angry in the first place?”
This is the part that I learned from working with dogs.  The more time you spend observing your dog, the better you become at predicting his behavior in any given situation.  This is where all the walking and observing really pays off.  If you spend enough time just observing your dog, you’ll know what he’s going to do when that cute sheltie from down the street walks by.  You’ll be prepared for his barking.  You’ll know that he’s going to run down the driveway like a wild animal and you know that trying to intervene and stop him at this point is an exercise in futility.  You’ve just made an accurate prediction of your dog’s behavior.  You know what to expect so you can prepare for his anticipated behavior rather than waste your energy on getting angry.
Have you ever noticed that your angry reaction is usually caused by something that surprises you?  It’s when someone or something in our life does something totally unpredictable that we react with anger.  Shrinks tell us that anger is grounded in fear.  Is it our fear of unpredictable situations that causes us to become angry?  Probably.
The trick to this whole thing is to remember to predict your dog’s behavior so that you don’t find yourself being surprised by unwanted behavior.  If a walk to the dog park usually results in a tug of war, then you can predict that behavior the next time you get out the leash and head for the park.  If Fido has developed the habit of barking at every dog that goes down your street, then you can predict this behavior and you can predict the kinds of things that will set off the behavior.  Rather than get mad at Fido for the umpteenth time, you can predict the situation and choose whether you want to take action to either avoid the situation or correct the behavior.  

Remember, your chances of successfully correcting unwanted behavior are much higher when you approach the situation without all that anger and butyric acid oozing from your pores.