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The English Mastiff dog is often defined as the biggest dog breed, a good family dog, a guard dog, and one of the most loyal dog breeds originating as estate guardians in England.  

And while all of these qualities are true, living with a Mastiff, or four in my case over the last 20+ years, provides a unique perspective of this giant breed dog that no Wiki article can offer. 

Considered the heaviest dog breed in the world, the Mastiff can weigh up to 230 pounds.  But with this massive size comes an even greater responsibility for the dog owner.  

To be clear, when I use the term Mastiff, I am referring to THE Mastiff.  Also known as English Mastiff or Old English Mastiff (OEM). It is important to make that distinction as, while there are many (lowercase m) mastiff breeds, there is only ONE Mastiff.  

More on this in a moment.

Mastiff 101: What is an English Mastiff? [And Why It Matters]

In this post you will learn: 

  • The history behind this ancient giant breed dog and why it matters,
  • The difference between the Mastiff and all other molosser dogs or types of mastiffs,
  • What the breed standard for the Mastiff is and why it matters,
  • The truth about Mastiff temperament, 
  • Facts about Mastiff breeders and Mastiff rescue you need to know, and
  • The harsh reality of Mastiff lifespan and what you can do about it. 

History of the Mastiff

As one of the oldest domestic dog breeds, Mastiffs descended from ancient Alaunt and Molosser dogs.  They were developed in England and nearly became extinct after World War II following the outlawing of bull-baiting and bear-baiting in 1835.  

The English Mastiff likely arrived in the United States during the colonial era, and a dog named Bayard was the first of his breed finally recognized by the American Kennel Club in 1885. (1) 

With a long history of both fighting in the arena in ancient Rome to guarding estates and castles in Britain, Mastiffs were bred for a very important purpose; to guard and protect. 

To expect anything less from the Mastiffs of today is a mistake. 

Why does the history of the Mastiff matter, you ask? 

1. Genetics Are In Control

Those that don’t know their history are doomed to repeat it.  Know what you are getting yourself into.   

An English Mastiff is not a Labrador retriever.  Likewise, it is not a Fox Terrier.  

If you don’t know how and why Mastiffs were originally bred and the genetics that make up the foundation of the breed, you can’t possibly understand what drives them to do what they do.  

This is critically important information to have when you attempt any kind of dog training, have behavioral issues, or want to improve any aspect of your life with them. 

2. Strategic Advantage

Understanding the purpose behind which a breed originated gives you a strategic advantage when it comes to training and behavior.  

Because I know Junior and Sulley naturally want to protect me, and that they become quickly uninterested if they don’t feel they are “on the job,” my job is to become more interesting.  To be so fun and exciting that they ditch their job-less boredom and follow me.  

Treats are more than enough to motivate a Labrador.  

With a Mastiff however, you will need treats, a squeaker, a clicker, maybe a soft toy or ball, kissy sounds, and anything else you can get creative with.  

Remember, a Mastiff’s job is watchman; they are guardians of their castle, not sheep.  

Mastiff breeds – Types of mastiffs

I mentioned above the critically important distinction between the capital “M” Mastiff and all other (lowercase “m”) mastiff breeds.  

Let’s dive into this a little deeper.

So often people will see my “Mastiff Mom” shirt and exclaim, “Oh, I have a mastiff, too!  He’s a Bullmastiff!”

It is at this point that I suppress my knee-jerk reaction to correct this popular mischaracterization of the Mastiff breed.  

I understand why there is confusion.  We are using the same word, mastiff, to describe both! 

The Mastiff (English Mastiff, Old English Mastiff) is one giant breed dog in a large group of other molosser dogs, which includes the Bullmastiff. 


If you have never heard that word before, it’s the term used for a category of solidly built, large dog breeds that all descend from the same common ancestor. 

The name derives from Molossia, an area of ancient Epirus, where the large shepherd dog was known as a Molossus. Molosser dogs are also referred to as molossoids. 

Breeds such as the Bullmastiff, Dogue de Bordeaux, Fila Brasileiro, Pyrenean mastiff (Mastín del Pirineo), Spanish mastiff, Neapolitan mastiff, Tibetan mastiff, and many others fall into the larger category of “Molossers”, but are not Mastiffs. 

Each is a separate and distinct breed.

Molossers typically have heavy bones, wide chests, pendant ears, a relatively short and well-muscled neck, and a short muzzle, though not all do. 

Interestingly, the AKC has been discussing adding a Working-Molosser Group to the AKC variety groups. The proposal would expand the now 7 groups to 11. 

This new group would include 20 molosser breeds now in the Working Group, Miscellaneous Group, and Foundation Stock Service. (2)

Here is a list of a few of the Molosser breeds and where they stand in popularity according to the 2020 AKC Working Group breed rankings. (3).

  • 8 Rottweiler
  • 15 Great Dane
  • 25 Cane Corso
  • 33 Mastiff
  • 52 Saint Bernard
  • 55 Bullmastiff
  • 71 Dogues de Bordeaux
  • 85 Anatolian Shepherd Dog
  • 93 Dogo Argentino
  • 98 Leonberger
  • 100 Neapolitan mastiff
  • 123 Boerboel
  • 140 Tibetan mastiff

The molosser dogs in the Foundation Stock Service listing on AKC are the Pyrenean mastiff, Spanish mastiff, Presa Canario, and Tosa Inu (Japanese mastiff). (4)

Interestingly, there are other molosser breeds such as the Fila Brasileiro which are not recognized by any of the aforementioned categories due to temperament.  According to the AKC, a Fila’s temperament is, “so incompatible with AKC sports and events that they will likely never seek, much less achieve, recognition.(5)

“Designer” Mastiffs

Designer Mastiffs come in all shapes, sizes, and configurations. 

A Mastiff mix can include such names as the American mastiff, daniff, and the mastador among countless others.   Despite the fancy official sounding names, these are nothing more than mixed breed dogs.  

Please DO NOT buy into the “designer” hype!  

A dog breeder trying to sell you a “dry mouth” Mastiff is not selling you a Mastiff.  They are selling you a mutt. 

If you are tempted by the marketing, read this: 

The Allure of Designer Dogs – A Mixed Breed Illusion

Mastiff Breed Standard

The English Mastiff is a giant breed dog characterized by a well-muscled, big-boned rectangular body that gets its height from depth of chest rather than length of leg, with a short double coat of fawn, apricot, or brindle stripes. 

Mastiff 101: What is an English Mastiff? [And Why It Matters]
©️ 2023 Big Dog Mom, LLC

The Mastiff is often referred to as a “head breed.”  The head is broad and massive, and a wrinkled forehead accentuates an alert, kindly expression.  

Average height and weights vary by sex with adult male Mastiffs reaching 30+” at the whithers and up to 230 pounds, and females slightly smaller at 27.5” and 170 pounds.  

In my opinion, a “doggie” looking female is preferred over an overly feminine light frame.  Afterall, a Mastiff is a Mastiff, regardless of sex!   

According to the AKC Official Mastiff Breed Standard

A Mastiff is:

“The Mastiff is a large, massive, symmetrical dog with a well-knit frame. The impression is one of grandeur and dignity. Dogs are more massive throughout. Bitches should not be faulted for being somewhat smaller in all dimensions while maintaining a proportionally powerful structure. A good evaluation considers positive qualities of type and soundness with equal weight.” (6)

american kennel club

If you are considering a Mastiff, here is why it is critically important for you to know the AKC Official Mastiff Breed Standard.

1. Financial 

A Mastiff is no small investment and a “bargain puppy” from a backyard breeder is often a costly mistake.  

One look at many of the dogs being used in backyard breeding programs and you can tell they aren’t well-bred.  Tall, thin bones, narrow heads, and chests, poor temperaments, and toplines, among many other obvious faults.  

These are Mastiffs who should not be registered, much less bred.  

2. Bred For a Purpose

Mastiff 101: What is an English Mastiff? [And Why It Matters]

Going back to the history of the Mastiff for a moment. 

English Mastiffs were bred to guard and protect estates and castles in Britain.  With fairly mild temperatures in England, there was no need for Mastiffs to have very long thick coats like the Tibetan mastiff or Saint Bernard.  [While there are “fluffy” Mastiffs, they are not an accepted coat type under the breed standard.]  

When you consider the job a Mastiff has to do, his body and coat need to be such that he is not hindered from his work.  

Mastiffs should be massive and powerful.  They should move with power and confidence – like a bull, not a gazelle. 

3. What Does Good Look Like? 

When interviewing dog breeders and searching for just the right Mastiff puppy, you should evaluate every single Mastiff you see against the breed standard.  This includes type as well as temperament, which we will get to in the next section.  

Ask yourself, “Does this look like a Mastiff?”  

Go to dog shows and put your hands on several Mastiffs.  Feel what a proper head feels like.  Watch how they move and react to their surroundings.  

The more familiar you are with WHAT GOOD LOOKS LIKE, the more likely you will find that perfect Mastiff puppy for your family. 

One of the single best resources for prospective Mastiff owners is the Mastiff Club of America. Established in 1929, the Mastiff Club of America is the official AKC Parent Club for the breed. (7)

Run by a network of preservation Mastiff breeders and owners, MCOA is a one-stop-shop for everything you ever wanted to know about the Mastiff breed. 

I recommend all serious Mastiff owners be members of MCOA in order to support and preserve the breed we love.  

Mastiff Temperament – Guard Dog or Gentle Giant? 

Having been the proud owner of four English Mastiffs, one female, and three male, over the last 20+ years, where do I begin? 

Let’s start the topic of Mastiff temperament with the definition given to us by the AKC Official Mastiff Breed Standard:

According to breed standard:

“Mastiffs temperament should be “a combination of grandeur and good nature, courage and docility. Dignity,rather than gaiety, is the Mastiff’s correct demeanor. Judges should not condone shyness or viciousness. Conversely, judges should also beware of putting a premium on showiness.”

american kennel club

MCOA describes the temperament of a Mastiff this way: 

MCOA on Mastiff Temperament:

“A Mastiff should possess a calm, self-assured temperament and be devoted to its family and friends. Mastiffs should not be aggressive to humans or other animals, including other dogs, although, unfortunately, some of them are. Mastiffs should be steady, gentle, eager for affection, good with children, calm and self-assured, and used primarily as a family companion.”

mastiff club of america

While the AKC and MCOA are spot on here, I’d like to take a moment and illustrate each of the adjectives above from my perspective as a long-time English Mastiff owner. 


Mastiffs are a massive, heavy-boned giant breed dog of courage and prodigious strength – a formidable protector of those they love.

When someone comes to the door, a Mastiff will confidently approach to ensure the safety of his home and his people, exuding strength, not insecurity.

Mastiff 101: What is an English Mastiff? [And Why It Matters]
©️ 2023 Big Dog Mom, LLC

Aggression, reactivity, and physical contact (i.e. lunging or jumping) are NOT appropriate or characteristic of the breed.  


Defined as “a readiness or willingness to yield to the wishes of others.” This is the opposite of aggressiveness.

Mastiffs are very sensitive, loyal, and desire greatly to please their people.


These adjectives harken back to what I said above about moving like a bull, not a gazelle.

Mastiffs are not a gregarious, friend-to-all breed.  Picture a bouncy Labrador with a tail moving so fast it’s about to lift off. 

That is not a Mastiff dog.

More typical, is a calm approach, sniff, and a slow, steady tail wag. Once greeted and assured of good intentions, a Mastiff will often go lay down until he is summoned again. 


As the AKC states, “shyness should never be condoned,” but, sadly, it is.  This characteristic is a huge problem in the breed today.

I recommend prospective Mastiff puppy buyers be VERY picky when it comes to the evaluation of temperament in breeding stock as well as puppies.

Keep in mind that all puppies go through fear periods when they are young and can exhibit an exaggerated wariness of strangers, beyond what is characteristic of the breed, and new experiences during these periods. 

Click here for more on fear periods. 


Most would define this as outright aggression (growling beyond a reasonable warning, lunging, or biting). 

This behavior is never ok, under any circumstance. 

Do NOT excuse or attempt to defend or minimize aggressive behavior. In cases of aggression, positive behavior modification and careful management are required.

Owners who respond to aggressive behavior with force will be sorry. 


Mastiffs are not a showy breed. 

Owners who hope for a dog with a “Look at me, look at me” attitude will be disappointed when all they get is a “Meh, I’m going to go lay down.” 


Mastiff 101: What is an English Mastiff? [And Why It Matters]
©️ 2023 Big Dog Mom, LLC

People are always surprised when they meet my Mastiffs at how calm they are.

No matter what I’m doing or where I go, Sulley and Junior want to be by my side.  They are not looking for attention or for me to entertain them. 

They are on the job at all times, making sure all is well with me.  Should their massive presence be needed, they will be right there.

Until such time, they are content to snore at my feet.

NOTE: In my experience, females tend to be more “on guard” than males. That is something to consider when deciding between sexes. 


Put another way, non-reactive. 

Reactivity is often caused by insecurity and fear, two qualities that are completely inconsistent with a guardian breed like a Mastiff. 

A dog constantly turning his head in reaction to sounds and stimuli, barking beyond a warning bark, jerking on a leash or cowering, obsessive about the world around them, and seemingly over-stimulated at all times, is a reactive Mastiff.

On the contrary, a proper temperament exhibits none of these things.

He is self-assured in his skin and his ability to guard his castle and his people, understanding that it is his presence alone that will deter evil-doers, not brute force. 


Mastiffs are eternally loyal and protective of their family. 


This quality cannot be understated.

While aggression can manifest through improper training and lack of socialization, the genetic component should not be discounted or minimized. 

If you are interested in more on this topic, read Life With An Aggressive Dog: A Letter To My Sweet Baboo and Nature Versus Nurture and the Drivers of Canine Temperament.


A Mastiff is not manic or reactive.  His temperament should be even and predictable. 

Rarely does the world around him cause him to react with dramatic highs or lows. He is a steady, dependable guardian. 


Mastiffs are often called a Gentle Giant, however, this one is debatable and it depends on your definition of gentle. 

Yes, when socialized early, a Mastiff can be very gentle with little children, smaller animals, etc. They have a natural empathy for those around them and their sensitive nature makes them particularly well-suited for therapy and assistance work. 

Mastiff 101: What is an English Mastiff? [And Why It Matters]

That said, there is no getting around their size and their lack of awareness of their size.  This inevitably results in human toes inadvertently being broken, bumps and bruises from giant heads or happy tails, and the occasional squashing of children who insist on playing Monopoly on the floor. 

More on this in a future post in this series, so stay tuned!


A Mastiff desires nothing more than to be with his people. While they do not require fawning attention and affection, their mere presence receives it. 

Yes, they have “work” to do, but I believe they consider your affection a perk of their employment.


Yes and No. 

The caveat here is that the relationship between children and dogs goes both ways.  Dogs need to be socialized around children from an early age, if possible, in a safe way. 

Children must be taught what they should and shouldn’t do around dogs and how to be respectful of their space.  I will write more on this topic in the future as it is a BIG one. For now, just realize that the quality of being “good with children” is not developed in the womb. 

Mastiffs are sensitive and naturally protective. They want to be a guardian for your children too, but not at the expense of their bodily autonomy threatened by disrespectful children. 

The Working Mastiff

Mastiffs were bred to be a guardian.  Therefore, they a guard dog whether you like it or not. 

As they see it, they are a watchdog over their home and their people.  No guard dog training required. 

However, there are many other jobs Mastiffs can do; scent work, therapy and assistance work, carting, barn hunt, obedience, and agility, just to name a few. 

Keep in mind, like with many other working breed dogs, when not given a job to do, they will find one.  Sadly, their idea of productivity usually means more work for you in the clean up!

I wrote in 7 Most Common Mastiff Myths: Facts From Life With a Giant:  

“Mastiffs are a working breed. …They need exercise.  A lot of it.  …These activities include continuous and regular socialization, obedience training, and access to green space to run and play for muscular and cardiovascular health.

If you think a Mastiff will be happy lounging around in your studio apartment from 8 am – 6 pm while you are away at work, the slobbery bits of paper and wood chips from your furniture will be evidence to the contrary.”

Are Mastiffs Hard to Train?

People often describe Mastiffs as stubborn and difficult to train. 

I respectfully disagree with this characterization.  

They are extremely easy to train once you figure out what motivates them. Owners need to be creative and exciting to peak and keep their interest.  

Mastiff 101: What is an English Mastiff? [And Why It Matters]
©️ 2023 Big Dog Mom, LLC

Your goal as the trainer is to be more interesting than the grass, smell, sound, or whatever else your dog is focused on.  Do not make the mistake of blaming your Mastiff’s disinterest in you with his stubbornness. 

One last point on what is a uniquely Mastiff dog trait.

They are extremely sensitive and are eternally loyal and protective of their family. As such, they have a natural wariness of strangers, so early training and socialization are essential. 

Harsh training methods (shock or prong collars, yelling, hitting) are NEVER necessary with a Mastiff and should NOT be used.  Positive reinforcement and encouragement are all that are needed to motivate a Mastiff.  

Be the person your Mastiff wants to be around and you will have a friend for life. 

Mastiff Breeders Near You

Before you make the decision to bring a Mastiff into your life, I recommend you speak with several preservation breeders first. 

Breeders have a deep passion and commitment to their breed and will view your inquiry as one more way to ensure Mastiff puppies end up in the right homes with the right people. They will let you know if you are not a good fit… which you want to know BEFORE you buy. 

As long as you are respectful of their time, dog breeders can be an invaluable resource to prospective buyers.

Here is how to find a Mastiff breeder near you:

  1. Go to a local dog show.  Find out what time Mastiffs take the ring and plan to be there right before.  Do not approach a breeder before ring time.  It is best to speak to them when the nerves and emotion of the ring are over and they have more time to relax and spend a few minutes with you.  Come prepared with questions, but realize dog show days are hectic.  They may only have a few minutes to chat at the show.  
  2. Mastiff Club of America – MCOA: Mastiff Breeder Referral Listing.  Keep in mind that just by virtue of being a member of MCOA offers no guarantee.  You must do your own due diligence.  The more breeders you speak to, the easier it will be to find the one for you. 
  3. Ask for referrals from Mastiff owners you meet at dog shows, parks, stores, etc.  Read the AKC Official Breed Standard so you are familiar with and know what to look for.  
  4. Ask your veterinarian for a referral.  

I have written extensively about the importance of selecting an ethical preservation breeder when it comes to buying a large or giant breed dog.  

For a deeper dive into this topic, read: 

Mastiff Rescue

If you are in a position to be able to rescue a Mastiff in need, wonderful!

Mastiff rescues are run by some of the most dedicated and selfless dog lovers I know.  Sadly, they are the ones seeing the consequences of dogs ending up in the wrong homes. 

Whether that is due to size, financial hardships, or behavior, there are Mastiffs of all ages and in all parts of the world looking for loving forever homes.  

For example, top dog handler, Carrie Klaiber, adopted a gorgeous 9-year-old brindle senior named Manny. Manny was rescued from a family who couldn’t be bothered with the needs of a senior Mastiff when they got a new puppy.  Carrie saved him and gave him everything he deserved; a soft warm lap on which to lay his big head and a loving human who would stand by his side until the end. 💔  Manny passed at 12.5. 

Here are two reputable Mastiff rescues I can recommend:

And for more information on the topic of dog rescue and dog breeders, read: 

Mastiff Lifespan

Despite heroic efforts to keep them strong and healthy, Mastiffs succumb to their great size earlier than most dog breeds. 

According to AKC, life expectancy for the Mastiff is 6-10 years. 

While the life expectancy of a Mastiff is short by comparison to smaller dog breeds, there are many examples of giant breed dogs who have lived long healthy lives well into their senior years. 

For example, Gunner from The Sandlot Movie lived to be 13 and I know several who reached 15 years old!  

Sadly, these are the exceptions, not the rule. 

The lifespan of a Mastiff is cut short for a myriad of reasons – most of which are health related.  

From osteosarcoma (bone cancer) and hip dysplasia to Wobbler syndrome, Mastiffs are at risk for many diseases.  

Health testing and delayed altering can help, but the fact is Mastiffs don’t live near long enough no matter what you do. 

Massive Commitment

Mastiffs can be magnificent companions, but acquiring a powerful giant breed dog is a huge commitment not to be taken lightly.

Stay tuned for the next post in this series; the financial responsibility of Mastiff ownership. 

Are you considering an English Mastiff for your family?  Share in the comments below!

Let me know what additional questions you have and I’ll try and include them in my next post and video. 

VIDEO:  English Mastiff 101 | How Well Do You Know the MASTIFF Breed? | TRUE or FALSE QUIZ

The latest on Youtube:


  1. Mastiff Dog Breed: AKC
  2. The American Kennel Club puts a Molosser Group on the table
  3. The Most Popular Dog Breeds of 2020
  4. Foundation Stock Service
  5. How Does a Dog Breed Become AKC-Recognized?
  6. AKC Official Standard of the Mastiff
  7. The Mastiff Club of America

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One Comment

  1. Love the videos. I would love to hear more about feeding. I have 3 large dogs. 2 English mastiffs and one dane mastiff rescue.

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