It has been my experience that you can take the most horribly abused dog and have them do a total 180 in a matter of a few months, if they have good nerves.
I often use terms like "weak nerves" and in contrast "good nerves". The average person might not know what these terms mean. I think a basic understanding of these terms is essential to understanding common canine behavior issues.
Good Nerves: A dog with good nerves is often happy go lucky and very confident. If there is a negative event or something that startles him, he quickly recovers. An example I can give is my new Boerboel pup. We were walking one day and large shaggy dog charged us. I knew the dog was behind an invisible fence. My pup did not. His tail and his ears went down. I assured him by saying "Come on! Lets go!". Within 5 to 10 seconds, after he realized there was no danger his ears were back up and the spring returned to his step. He barely bothered to look over his shoulder.
Weak Nerves: A dog that has weak nerves is best described as skittish and nervous. Every startling event is a very traumatic event in this dogs eyes. It takes him much longer to recover from the event than a dog with good nerves. These sorts of dogs are often very reactive. They are typically leash reactive in that they feel that they must defend themselves from every dog and every person. This sort of dog may snap at its owners if it is startled. The world is a very scary place to this dog.
Whether a dog has good nerves or not is mostly determined by genetics. Training and conditioning can improve things, but only so much. We are who we are. In this regard dogs aren't that much different than us.
Rescues will often have a dog that comes across as skittish. The story that they most often tell is that the dog was abused. In many cases, if you press the rescue with pointed questions with regards to the history of the dog, one comes across alot of "ummms" and "ahhhhs" which go on to become a lot of unknowns in the dog's history. Besides, these folks will tell you that "people suck" and you can't trust what they say. So how come if it comes to abuse without any physical signs the stories are to be believed yet other times people can't be believed.
But please do not let these statements detract from all the poor souls that obviously were abused and have the wounds to prove it. These dogs do deserve your pity and I appreciate anyone that donates in hopes of providing life saving care. There are a whole bunch of rescues the are very legitimate and honest. I appreciate anyone that supports the good ones. I just want to make sure that the good ones survive and the ones that do more harm than good go out of business. Those that lie need to stop.
Perhaps the rescues that do make up the abuse tales do it because they feel that it will help the dog get adopted or better yet might bring forth a large donation. In my eyes it is very unethical to make up stories. When you lie to someone and they later find out, trust has been shattered. A rescue should always try to look at the long term picture. Would you rather have that donation now and have it be a one time thing or would you prefer the support over many years?
It has been my experience that you can take the most horribly abused dog and have them do a total 180 in a matter of a few months, if they have good nerves. I have seen some incredible success stories. You can take a dog from the best home, with the best care and have it be nervous and aggressive.
In the case of the nervous aggressive dog, some will claim that the owner has a weak energy. That does make for interesting TV but it often isn't the truth. Yes, a brat, ill behaved dog might be due to lack of structure in the dog's life but the nervous dog in the good home is more than likely genetics.
If a rescue or a trainer tells you that it might take years for a dog to get rid of his nervousness, the training program is either very ineffective or the dog has really bad genetics. Good trainers can turn a dog around very quickly. One of my dogs, that came from a rescue more than likely had been "kicked around" a fair bit. This particular dog is very strong willed. I had a night and day difference in her attitude towards life and people in a matter of weeks. One could not find a more affectionate dog.
If you want a dog with weak nerves, go to a puppy mill or a pet store that sells dogs (the practice fortunaltely is quickly going extinct). Dogs that come from puppy mills often have issues and it wasn't just their treatment while in the mill. It is largely genetics (poor breeding) and some other factors like being removed from the mother at too young of an age.
If you want a dog with nerves of steel go to a working-line breeder. These breeders typically have a massive amount of pride in their product. I am using the word product because things are really that cold sometimes. In defense of these breeders, they do not want to contribute to the problem. "Undesireable" dogs are often culled at a very young age. Before you race off to the nearest working line breeder be advised that these types of dogs despite being very sound genetically, require the level of effort of a second full-time job. There are non-working line breeders that produce dogs of very sound temperament and health. One just needs to do extensive research.
You can also get some very good dogs from rescues and the pound. You could go with a trainer or behaviorist to make the selection. Go look at five hundred dogs and pick one. Do not make a rushed decision - a dog is for life. Do yourself a favor also, close your ears to what the rescue person has to say. Let the trainer/behaviorist do the talking. More importantly, let your eyes and brain make the decision and not your heart. The heart will often lead you down a very long hard road.
-- Daniel Audet