[Just another Joe]

Do you know if they train the dogs to target that area?

From all I have read, seen, and discussed with dog handlers, they are not.
They are actually trained to go for a hand or arm to help incapacitate one upper extremity so the officer can handle the other one.

[phothus]

the arm attack is a by-product of many German dogs having done Schutzhund training which uses an arm sleeve for the protection work.

Many K9’s are now trained with bite suits where they are also trained to attack the legs. A leg bite is almost a certain way of bringing a suspect to the ground quickly - it allows the dog to quickly win the fite and to incapacitate the suspect, and is generally a better attack.

They are not trained to bite that area, but a good dog will get what he can when he attacks.