Top 10 Most Aggressive Dogs

"Aggressive" can cover a wide berth of meanings when it comes to canines. An aggressive dog may be one that is not under the control of his owner and lashes out at people with or without provocation. An aggressive dog may be sought for his fiercely protective tendencies by those seeking guard dogs. As with all breeds, firm training and responsible housing are necessary to ensure a dog with aggressive tendencies remains a good citizen.

A 2000 study by the Centers for Disease Control and Prevention studied nearly two decades' worth of dog bite fatalities and was one of the only reports of its kind to single out breeds. This can be difficult because of weak breed definitions, as evidenced by the No. 1 culprit on the CDC list: "pit-bull types."

• Pit bull: This term can loop in breeds and mixes including the American Staffordshire terrier, the American pit bull terrier and the American bulldog. Stocky and muscular, these dogs have been used for hunting and bred for fighting, leading to breed-specific restrictions from apartment complexes to municipalities.

• Rottweiler: The American Kennel Club notes that this powerful, large dog can be aggressive toward other dogs and possesses an "inherent desire" to protect his people and his turf.

• Perro de Presa Canario: These powerful dogs have been involved in high-profile mauling incidents since the release of the CDC report. Some security companies favor this breed for personal or property protection, but stress that a responsible owner who has experience with working dogs is needed to adapt the Presa Canario into a good pet.

• Wolf dogs: The greatest number of incidents in the CDC report attributed to mixed-breed or hybrid dogs was with domestic dogs that have been bred with a wolf. The International Wolf Center notes that aggression may be "unpredictable" and even "hard to control" in these dogs.

Think of these breeds as watchers of your family and property who have the strength behind the bark to ward off danger.

• Bull mastiff: Powerfully built and alert, this dog tips the scales at more than 100 pounds and will use that muscle to protect his family. Within the family unit, though, he should be more of a loving pup than an intimidating force.

• Doberman pinscher: The AKC deems aggression toward other dogs from this sleek, energetic breed to be normal, but "viciousness" toward either a handler or a judge will get this dog booted out of the show ring. Dobermans are expected by nature to be fearless and protective, but obedient as well.

• Chow chow: Owners of these big, fluffy dogs can find that their protectiveness and dominance can lead to acting out aggressively against perceived intruders and other dogs.

• Dachshund: Don't underestimate the potential for aggression in little dogs. A 2008 study found that wiener dogs were most often reported snapping at strangers and other dogs, and occasionally their owners.

Police departments need canines in their units who are strong, agile, quick and able to pursue and potentially take down a fleeing suspect.

• German shepherd: The AKC breed standard says that the dog should be "direct and fearless, but not hostile," and its confidence translates to being a consistent watchdog or helping lead the blind down a crowded street. These dogs also work in military units. In all work capacities, these dogs receive extensive training along with their handlers.

• Belgian Malinois: Police departments call upon this dog as a more compact member of the canine patrol. The AKC notes that this breed bonds closely to people he knows but will be protective when strangers come around. "Correct temperament is essential" for this worker dog, the breed standard notes.