PLEASE HELP!

Question
I have a 2 year old Rhodisian Ridgeback mix and he is extremely dog aggressive. We got him from a shelter and they know nothing about his history. When we take him for walks he will go into kill dog mode if he sees,hears or smells another dog. I was wondering what type of training should I use? Also should I use a E collar or will that make him worse? Or maybe even tranquilizers? This is kinda last resort for him and I wanna do as much as possible to help him.

Answer
Since I cannot see your dog's behavior, I can't tell if it's related to pure aggression, or if he is simply leash reactive.  You really should engage the services of a qualified behaviorist.  If you need a referral, call the nearest vet school, or visit the Animal Behavior Society or IAABC web page.  In both cases, your primary responsibility is to keep others safe.  So, assume aggression, and be thankful if it turns out to be reactivity.  These situations are often the result of improper socialization and training in puppy hood, but are handled similarly in the adult dog, with a regimen of classical conditioning and desensitization.  There's a book on the subject by Emma Parsons, called "Click to Calm" which I recommend.  Understand that the Rhodesian Ridgeback breed is known for aggression toward other animals, and in an under-socialized dog that can be very problematic.  Please do NOT, under any circumstances, use an electronic shock collar on an aggressive dog.  You may make matters much, much worse.  If anything, try to figure out at what distance your dog begins to react to other dogs.  Let's say it's at 300 feet.  My advice would be set things up so that another dog approaches at 305 feet away, and start feeding your dog some great food, such as chicken, roast beef, tripe or duck, as soon as the dog appears, but STOP feeding when the dog goes out of sight.  Do not feed AFTER your dog is already reactive.  What you must do is work "under threshold" so that he is learning that the appearance of another dog causes you to feed him, and that you are pleased with him for NOT reacting.  Do get some help with this, though, as you are dealing with a large, powerful breed, and I cannot make any kind of accurate assessment of your situation without first hand knowledge.