Worlds Most Aggressive Dog Breeds

Updated on April 17, 2016
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Anna studied psychology, law, English, and animal welfare in college. She is a mother of two and aspires to become a vet some day.

What Makes Dogs Vicious?

What makes a dog aggressive is highly disputed amongst dog-owners and breeders. While many people insist that even the most 'dangerous' breeds can make excellent family pets with the right amount of socialisation and proper, firm training, others believe that certain breeds of dog are more high-risk than others due to their breeding history, for example, many dogs such as the German Shepherd, have been bred purely to guard and protect their families, which means that while they are fantastic family pets, and usually safe around the families children, they can be over-protective, which can result in injuries to strangers.

presa canario
presa canario

Dogs Bred for Fighting - The Presa Canario

The Presa Canario is a massive breed of fighting dog, which has been known to attack and kill humans. They were bred originally for an Aryan Brotherhood dog fighting ring, but have also been used for guarding livestock. The Presa Canario, also known as a 'Canarian Catch Dog', require very early socialisation and obedience training, but been with a very experienced owner, they are not safe animals to own, and are a danger to people and other animals.


Tosa Inu

The Tosa Inu is one of the world's most dangerous dogs. This massive dog breed can typically weigh anywhere between 130-200lbs and stands around 32 inches tall. It is legally banned in many countries due to the aggressive nature of the breed. It originated from Japan, where it was bred to be a powerful, muscular dog for fighting other dogs, however, even the best trained dogs of this breed could become over-protective and attack humans.

Neapolitan Mastiff

The Neopolitan Mastiff is famous for the role of Hagrid's pet dog, Fang, in the Harry Potter films. Although in those particular films 'Fang' is a docile, lazy creature, in reality these dogs are banned in many different countries. They have been used as war dogs by the Roman Legions and also as gladiator dogs in the bloody 'sport' within the colosseum in Italy, where the breed originated. Males can top 200lbs and are strong, wilful and vicious.


Gull Dong or Pakistani Bulldog

The Gull Dong is another breed that, sadly, was specifically developed as a fighting dog. It is also known as the Pakistani Bulldog, and is the result of a Bully Kutta crossed with a Gull Terrier. This dog is extremely aggressive, and made even more dangerous by the fact it is defiant, difficult to control and is incredibly powerful, muscular and athletic. This breed should never be kept by any person who is not an expert in dog-training, as if they are not trained properly and socialised from a very early age they will turn aggressive towards people and other dogs.

Pit Bull Terriers

Pitbull Terriers have been selectively bred from a range of other terrier breeds and bulldogs in order to create a dog breed that was second to none in dog-fights. The people who set out to do this succeeded - this dog is recognised toehold the number one rank for pound-to-pound lean muscle tissue. Although this breed is capable of being a loyal, friendly pet and excellent guard dog, sadly this breed type has attracted the wrong kind of attention from around 1980, where these dogs were bought by many criminals and people involved in dog-fighting rings as a statement of masculinity. Aggressive dogs were bred and encouraged to be aggressive towards other canines in order to be excellent fighters, and as a result, many once friendly, sweet-natured breeds are now illegal in many countries and American states. They also have an extremely high prey-drive that is triggered by smaller mammals, meaning families with smaller children would be incredibly unwise to own this dog. Many bites have resulted in fatalities to both adults and children throughout history.

Caucasian Ovcharka
Caucasian Ovcharka

Breeds for Hunting and Guarding

The Caucasian Shepherd, also known as the Caucasian Ovcharka, was bred for the purpose of guarding homes and livestock. It is a courageous and strong-willed breed which can make training problematic. It is also prone to attacking strangers due to the fact it is highly territorial. It is fearless, dominant and powerful which makes dogs of this breed very dangerous if they are not well trained. Males weigh at least 110lbs and stand around 30 inches tall. Even though many families insist that this dog can be good with children, it is strongly recommended the two are not left alone as accidental injury can easily occur.

Rhodesian Ridgeback

The Rhodesian Ridgeback is renowned for being used to keep lions away from it's master and also prey while it's owner hunted game. This dog makes an incredibly loyal companion if it is well trained, but if it is not kept by an experienced dog-owner who does not spend almost all their time with the dog, this breed is known for becoming dominant and can be prone to developing a highly aggressive side, with other dogs and also people.


St. Bernard

The Saint Bernard is another huge breed of working dog, which originally was bred in the Italian Alps. Although they are portrayed in many films and photographs as giant teddy bears, in reality they are very stubborn and difficult to train, and require very early socialisation. Saint Bernard's are renowned for rescuing people who have become lost in mountainous areas.



The Basenji is a beautiful breed of dog, and has been classified as a sight hound for it's incredible intelligence, constant alert state and loyalty. However, they are known as the second most difficult breed to train, and can become aggressive towards other dogs and strangers if they are not properly trained.


Dogo Argentino

The Dogo Argentino was originally bred for hunting large game such as wild boar and pumas. It is illegal to own this breed in the United Kingdom under the Dangerous Dogs Act 1991, due to a number of attacks. Whilst it is friendly, loyal and affectionate towards it's owner, this breed is fiercely protective and will not hesitate to turn on strangers if it believes they are a threat. They are extremely territorial, making them excellent as guard dogs, but vicious, as stated previously, and will instantly defend it's territory and family against intruders.

Boer Boel

The Boer Boel is a large mastiff breed originating from South Africa, which was selectively bred for the purpose of guard dog. Like the Dogo Argentino, their loyalty to their family can make them vicious towards strangers and other dogs.


German Shepherd

German Shepherds, as the name suggests, originally came from Germany, and are very popular as pets and also police dogs. They were bred to be superb guard dogs, and fill this role very well due to their territorial nature. However, they are known to become over-protective and this breed has been known to bite humans who have been thought of as threatening to their 'pack' or individuals who have 'intruded'.


Rottweilers have also been bred to be heavy-duty guard dogs, and can be very good as such. Unfortunately Rottweilers have earned a bad reputation due to a fair number of attacks on both people and other animals, including livestock such as sheep, which have died as a result.

Many individuals say these instances occurred due to poor training and a lack of socialisation, but it is generally agreed that this breed is prone to developing a vicious streak if managed incorrectly, can be overprotective of its family and home and also has a high prey drive - more than a handful of Rottweiler attacks have happened recently involving toddlers.


From 1982-2012 there have been at least 48 instances reported of Boxer dogs causing significant injury to humans. They can be wonderful family pets if their owner has had previous dog-handling experience and is able to decpdicate time and effort to training, but without this they can be boisterous, dominant and aggressive, meaning they can be a danger to people. This breed is known to be extremely affectionate towards the family it lives with and seeing this well-loved breed on a list with other dangerous breeds may come as a shock, but it is not recommended to pick this dog breed if you have never owned a dog before.

The Chow Chow

The Chow Chow, affectionately known as the "fluffy lion dog" originated from China and is considered high-risk as a breed. There have been 238 fatalities from dog bites from 1979 to 1998 due to this breed being so fiercely protective of it's owner. It is also a large, heavy breed meaning that it can be a danger to small children, even when it is only playing.

Let me know what you think!

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    • profile image

      Davi 10 months ago

      Dogs in some of the pictures were not the dogs they were describing,also pits are good with children.don't think the author know much about dog breeds

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      Crystal Galvan-Casas 14 months ago

      I bred Chow Chows. Mine were bred and trained with love. The only ones that were in danger were people that had no business or permission to be in or at our home. Raised 2 girls with them and the chows were very protective of them. Chows were initially bred for the Chinese royalty, hence the name. Bred to protect one person which is what they do. With love they are great pets.

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      Robert 15 months ago

      At guarding doga you forgot dobermann

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      Val 18 months ago

      I'm more afraid of an ankle biting chihuahua, than I am of a pit bull. Evil dog fighters & animal abusers in general, should take the "most vicious" spot in place of pits.

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      Faye 19 months ago

      The Caucasian ovcharka on this article is in fact a Photo of a TIBETAN Mastiff.

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      Ida 22 months ago

      I agree St. Bernards can be a hassle to train, but I personally have dog sat a lost of them. They get right up in your face, and lick you all over. This breed, in my opinion, isn't a first choice for first time owners, though I must say they are very affectionate large beasties.

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      Pepper 3 years ago

      You've hit the ball out the park! Inerldibec!

    • TolovajWordsmith profile image

      Tolovaj Publishing House 3 years ago from Ljubljana

      Every breed was raised for certain purpose. If they stay under control, I don't have a problem with aggressive breeds.

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      ohcaroline 3 years ago

      I've never been fond of large dogs mean or otherwise. I don't like to be around them when they are aggressive. My next door neighbor has a large mixed breed dog and when she takes it out to walk it...I stay indoors because it will get aggressive and we share the same carport. I don't try to get in my car when she has it out.

    • LornsA178 profile image

      LornsA178 3 years ago

      I learned a lot about dogs today, I never thought that Saint Bernard could become aggressive if not trained properly. Thanks!

    • VioletteRose LM profile image

      VioletteRose LM 3 years ago

      Great lens! I love dogs, so this information is really important. Thanks for sharing.

    • tazzytamar profile image

      Anna 3 years ago from chichester

      Wow KonaGirl that's fascinating! They sound like incredibly vicious dogs... I definitely wouldn't want to be the boar! Thank you for letting me know about the Aryan Brotherhood too - I must have mis-read something while researching for this article, I will double-check and correct that mistake!

    • Kailua-KonaGirl profile image

      June Parker 3 years ago from New York

      Some of these breeds I had never heard of so found this article very interesting. I have to disagree with you about the Aryan Brotherhood originally breeding the Presa Canario. This Spanish dog breed is much older than the existence of the prison gang. In Hawaii, my relatives cross bred Pit Bulls and Bull Terriers for a special bred to hunt wild boar. Very dangerous dogs and now a common breed in the islands. They have the stature and strength of the pit bull with the ability to lock their massive bull terrier jaws on the pig and anyone else that gets in their way.

    • tazzytamar profile image

      Anna 3 years ago from chichester

      That's so true Janis - pit bulls really can be lovely, but they just seem to be one breed that's become a 'status' dog with people who have mo idea about training or handling.very sad, as many animals then have to be destroyed because they weren't provided with proper care and attention.

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      WriterJanis2 3 years ago

      We used to have a pitbull. We adopted her as an older dog. She was the most gentile dog I have ever known and was wonderful with our children. It's sad when some pet owners try to make their dogs so mean, when they can be so kind.

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      Miha Gasper 3 years ago from Ljubljana, Slovenia, EU

      It's very interesting to see how different can be breeds. I believe owners of most aggressive breeds should possess some kind of certificate proving they can handle them. I also think some breeds are simply not suitable for city areas with a lot of people and not enough space for running. It's just not fair to dogs and can be dangerous for dogs and people.

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      Anna 4 years ago from chichester

      @BLouw: How awful for the family! I agree though - no dog is truly safe, I would never leave my child alone with one no matter how big, small, laid back etc. You never know and it just isn't worth the risk

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      Barbara Walton 4 years ago from France

      I remember as a child neighbours had two Chow Chows and they attacked their little girl and bit all the way up her arms. I'd always be safe and choose a real family breed of dog and never trust a dog with a young child.