October 6, 2009: The U.S. Marines are banning pit bulls, Rottwilers and wolf hybrids from base housing. The other services have similar bans, but leave it up to base commanders to implement it. While marine families have about as many dogs as the general population, they have a higher proportion of "aggressive breeds." Wolf hybrids were included here not because wolves are particularly vicious, but because wolves do not act like domesticated dogs, and tend to be uneasy around humans, and consider other animals a potential meal. An increasing number (nearly one percent) of the 75 million dogs in the United States are wolf hybrids, a subspecies of wolf that does not, like domesticated dogs, know how to learn to recognize what humans are up to (by reading facial expressions and body movements, skills dogs were bred for over thousands of years). Pit bulls and Rottwilers have been bred, for centuries, to be aggressive and lethal, particularly against other animals.

Marines with any of the banned dogs can get a waiver if their dog can pass a standard (American Kennel Club) temperament test. This includes items like being friendly with strangers, calmly submitting to petting and behaving well with other dogs. However, the aggressive breeds are not only more likely to bite in general (nearly five million Americans a bitten by dogs each year), but are more often the cause of severe injuries. While only 15-20 Americans die from dog attacks each year, about eight percent of those bitten end up in a hospital. Moreover, many more pets (dogs and cats) are killed or injured by aggressive dogs each year.

Marines are trained to be aggressive, and many prefer aggressive pets. But the presence of children, and nervous wives, often leads to aggressive pet dogs being abandoned, which is also a problem on bases. The new policy is meant to motivate marines to at least get their dogs trained to behave around strangers (both people and other animals).