Choke chains can increase aggression

I got a sad call from a new client yesterday. She said her dog was showing signs of dog-dog aggression and, from the advice of someone in the dog park, she hired a trainer that uses choke chains. She said initially the training wasn't too physical, but she ended up firing him because of his increasingly abusive techniques when dogs were around her dog.
She noticed that since those sessions, her dog has gotten worse, and more anxious when dogs come into view. I was not surprised and told her that is one of my main reasons for never recommending physical, or fear-based training.

From a learning perspective this is what can happen and probably happened in this case:

• Her dog showed signs of aggression
• She got "popped" with the choke chain which is called "positive punishment" (many people and trainers incorrectly call this "negative reinforcement")
• The pain possibly stopped her barking, but actually increased the anxiety (she was anxious about dogs coming into view because now it meant pain for her)
• Her behavior escalated over time because now she became anxious about getting anxious. The way I explain this is that the pattern has been consistent that she will bark at some point, and now she has to worry about two things: the dog and the pain associated with the dog
• She can't win. Either she shows anxiety and gets choked, or she has to quietly endure a situation that causes her fear

Dog-dog aggression can be modified using only positive reinforcement. I have been thinking about it for a while, but I am going to write a Dog Aggression E-book as soon as I can. I am editing videos for my dog training video site, but it will be a while before I have a dog aggression video. An E-book can be helpful and I have to help people realize that you don't have to use abusive methods to work with an aggressive dog.