5 - Alaskan Malamutes

Weight: 75-100 lbs.
Origin: Nordic

The Alaskan Malamute is a generally large breed of domestic dog (Canis lupus familiaris) originally bred for use as a utilitarian dog, not just an Alaskan sled dog. They are sometimes mistaken for a Siberian Husky, but in fact are quite different in many ways. As pets, once mature, Malamutes have a very quiet, dignified temperament and are loyal to their owners.

These dogs are very energetic and active. If they are bored, they can become destructive. That's why this dog needs lots of exercise to be happy.

4 - Huskies

Weight: 44-66 lbs.
Origin: Alaska

Husky is a general name for a type of dog originally used to pull sleds in northern regions, differentiated from other sled dog types by their fast hard pulling style. The Alaskan Malamute was used for heavier loads and is generally slower in long-distance dogsled racing against smaller and faster Husky type dogs. Huskies are still used in sled racing, and in recent years companies have been marketing tourist treks with dog sleds for adventure travelers in snow regions as well.

Very energetic and intelligent dogs. Not considered a good guard dog because of its personality characteristics and gentle temperament.

3 - German Shepherds

Weight: 70-100 lbs.
Origin: Germany

The German Shepherd Dog (German: Deutscher Schäferhund), also known as an Alsatian or just the German Shepherd, is a breed of large-sized dog that originated in Germany. The German Shepherd is a relatively new breed of dog, with its origin dating to 1899. As part of the Herding Group, the German Shepherd is a working dog developed originally for herding and guarding sheep. Because of its strength, intelligence and abilities in obedience training it is often employed in police and military roles around the world. Due to its loyal and protective nature, the German Shepherd is one of the most registered of breeds.

These dogs are intelligent and very alert. They are highly used by local authorities such as the police K-9 unit. German shepherds are known to be fearless and confident dogs.

2 - Rottweilers

Weight: 100-130 lbs.
Origin: Germany

The Rottweiler is a medium to large size breed of domestic dog that originated in Rottweil, Germany. The dogs were known as "Rottweil butchers' dogs" (German: Rottweiler Metzgerhund) because they were used to herd livestock and pull carts laden with butchered meat and other products to market. Some records[which?] indicate that earlier Rottweilers may have also been used for hunting, although the modern Rottweiler has a relatively low hunting instinct.

Rottweilers are known to be very aggressive dogs because of their keen territorial instincts. That's why they make great guard dogs.

1 - Pit Bulls

Weight: 55-65 lbs.
Origin: United States

A Pit bull is any of several breeds of dog in the molosser breed group. Many jurisdictions that restrict pit bulls, including Ontario, Canada, Miami, Florida, U.S. and Denver, Colorado, U.S., apply the restriction to the modern American pit bull terrier, American Staffordshire terrier, Staffordshire bull terrier, or any other dog that has the substantial physical characteristics and appearance of those breeds. However a few jurisdictions, such as Singapore and Franklin County, Ohio, U.S., also classify the modern American Bulldog as a "pit bull-type dog", while in the United Kingdom a pit bull is an American pit bull terrier. 

All of the breeds share a similar history, with origins rooted from the bulldog and a variety of terriers. The dogs called bull terriers before the development of the modern Bull terrier in the early 20th century may also be called pit bulls.

A pit bull is a fearless dog that will take on any opponent. They will lock their jaws onto the prey until it's dead. Pit bulls have a reputation of mauling people to death and they are highly sought for dog fighting.