 Using the Em dash You can use the em dash in place of commas or parentheses

Em dashes in place of commas  A pair of em dashes can be used in place of commas to enhance readability.  Example:  “And yet, when the car was finally delivered—nearly three months after it was ordered—she decided she no longer wanted it, leaving the dealer with an oddly equipped car that would be difficult to sell.”  That information between the em dashes is not necessary to the meaning of the sentence.  It simply provides added detail.

Em dashes in place of parentheses  A pair of em dashes can replace a pair of parentheses.  Dashes are less formal than parentheses and are more intrusive.  If you want to draw attention to the parenthetical content, use dashes.  Ex:  “Upon discovering the errors—all 124 of them—the publisher immediately recalled the books.

Which of these choices is the BEST way to use an em dash?  Pitt bulls, known for their activity in dog fighting—are actually sweet, loving animals.  Pitt bulls, the most loving of all dogs, has not always been so— positively thought of.  “Aggressive” breeds are often judged;—but their demeanors are determined by the person who raises them.  One quality that is prevalent in pitt bulls—evident in many other aggressive breeds—is loyalty and devotion to their owner.