Is your mom a police officer or does she want the dog to be attack trained? Protection training is very serious and costs in the thousands. You can buy an already PP trained dog but those go for around 20,000. When a dog is PP trained it also becomes major liability and some insurance carriers refuse people who have PP trained dogs. You do not want to get a PP trained dog unless you plan on a dog that will take down someone. What if the dog accidentally gets loose? Major liability and takes a huge amount of control, management, and responsibility.
A well bred GSD will naturally be protective and that generally is enough of a deterrent. 99.9% of the time when people say that want to PP train a dog, they have no idea what that actually entails with the time and money, and they don't follow through with it.
A GSD that is a good candidate for PP training would be one with high drives from working lines. These dogs are not always the easiest to live with if they do not have a job or 3.
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