Breed Mastiff

BreedsAbout the Breed: Mastiff

The Mastiff is a devoted, gentle, slobbery, loving companion that requires just the right owner.


The Mastiff is an ancient breed. When Julius Caesar led an invasion of Britain in 55 BC, he was impressed by the mastiffs who helped defend the island against his legions and made note of it in his campaign journal. Not long after, British mastiffs were brought back to Rome to battle wild beasts and human gladiators in the arena.

The Mastiff as we know it came into focus in medieval England, used as big-game hunters, nighttime guardians of estates, and war dogs. In the “Canterbury Tales,” Chaucer calls them “Alaunts” (a French breed name) and says they were “as great as any steer/To hunt at the lion or the deer.” Mastiffs fought alongside the British against the French in 1415 at the Battle of Agincourt, later immortalized by Shakespeare.

At the end of World War II, England stood victorious but depleted. It was estimated that only 14 Mastiffs survived in the entire country. The Mastiff population was rebuilt with the help of U.S. breeders who exported specimens from good British stock back to the mother country. Today’s Mastiff is more docile and friendly than his ancient forebears, but no less courageous.


Owning a Mastiff is a major responsibility but they will reward you a million times over with their love. They are not the breed for everyone however, due to their size and their need to be a major part of your family.

Mastiffs are not the type of dogs to be left outside chained to a doghouse, or left alone in a fenced yard. They thrive on being house dogs sharing your life, and will follow you from room to room as you do your work, hoping that you will spend more than a moment in each room (after all it takes a lot of effort to keep getting up after they’ve been lying down!). They are devoted to their owners and want to have contact with them frequently. Some want to touch you all the time to reassure themselves that you are still there. Without lots of human companionship, behavioral problems can occur when a Mastiff is relegated to the back yard with only occasional human contact.

Mastiffs are very sensitive dogs and the sternest of voices is all you need for discipline. They respond well to love, praise, and especially treats. Obedience training (which is a MUST) should not be negatively based nor should it be the type where the dog is jerked around using different types of collars.


Best with:

  • Owners willing to provide positive reinforcement obedience training: it is imperative that obedience training be done for a Mastiff, to avoid being pulled down the street when your 185 lb. male wants to chase that squirrel.
  • Families with older children (the swinging tail of a Mastiff can knock a small child over).
  • Fenced yards
  • People who like big wet slobbery kisses, snuggling, and being touched most of the time by their dog—whether to sit on their feet, put their head in their lap, or put a paw on their leg to say Hi!

Not for:

  • People on a budget: an adult male Mastiff can go through 70-100 pounds of dry dog food a month. Due to its size, a Mastiff will also cost you more money at the vet’s office. Medications are typically dosed by weight, so a week’s supply of antibiotics for a smaller dog will cost five times as much for a Mastiff.
  • Small homes: although a small house can work as long as the Mastiff goes for regular walks and plays outside.
  • Small cars: Mastiffs want to go everywhere with you—rides with you to the park, beach, post office, and grocery store.
  • Unfenced yards: Mastiffs will go seeking human companionship when they can’t find it readily available.
  • People who expect a guard dog: Mastiffs will protect their family more like a watch dog than a guard dog. If your intent is to have a guard dog then you must think about another breed. They will often bark and let intruders know they are not accepted. Once you accept the guest, chances are good that they will too. On the positive side, their mere presence and bark may scare the bravest of burglars.


Easy-going, affectionate, gentle dogs who are not merely “pets” but rather “members of the family.”


  • Slobber: be prepared to wash your walls, ceilings, etc. whenever they shake their heads. Slobber rags must always be handy in strategic locations all over the house. Mastiffs always seem to drink right when you are ready to walk out the door for work!
  • Snoring: Are you a light sleeper or one that needs constant quiet to sleep? If so, consider another breed. Mastiffs will snore so loud you might think a train is going through the house. And because they want to keep you warm at night on the bed, or at least sleeping in the same room, it’s hard to get away from the noise.
  • Territorial: Mastiffs will protect their yard, house, car and family from people or dogs. They want it to be known that this is their yard.
  • Change-Averse: Mastiffs have a difficult time with change. This is particularly noticeable with rescue Mastiffs… who’s already feeling traumatized by the changes that have occurred in their life. They are not ready to be the perfect pet you have read about in books. Be prepared to be understanding and help them through the rough spots. Your efforts in doing this will be greatly rewarded.



As the largest of the dog breeds, Mastiffs can range in size from 26 inches to 36 inches at the shoulder, and weigh anywhere from 120 pounds to 225+ pounds.


Apricot, brindle, and fawn, with a black mask.

Energy Level:

Minimal. A couch is the Mastiff’s idea of the perfect place to spend a day, but exercise is important to keep them fit and help them live longer.

Life expectancy:

On average, 6 to 10 years.


Mastiffs are wonderful with children. They are very gentle and quite tolerant of ear and tail pulls, having a child sit on their backs (though not a good idea), and they adore licking kid’s faces. They will protect their children. If you have very small children who are just learning to walk, you may want to wait until they are older before getting a Mastiff whether it’s a puppy or a rescue dog: the swinging tail of a Mastiff can knock a small child over. Of course, please make sure that you supervise and train your children to respect and treat the dog well. In rescue, we will not place a dog with a family with small children unless the dog has been raised with them in the previous home.

Other animals:

Mastiffs can be very good with other dogs and with cats, as long as they have had good experiences with them. If you have an adult male dog already and you are getting a rescue, you might want to consider a female Mastiff and vice versa. This is not to say that two males cannot get along, but males especially have a tendency to want to dominate each other if they have been recently neutered.


Mastiffs are best at being family companions.


The ears and the deep wrinkles around the Mastiff’s head, eyes, and muzzle should be regularly inspected and cleaned. Their coat needs only a quick brushing every few days. During periods of heavy shedding (once or twice a year), more frequent sessions with a strong, toothed comb are recommended to remove dead hair.


It is important that an adopter understand the potential for the following health conditions or problems to develop in any Mastiff, regardless of the line, pedigree, breeder, or testing of ancestors.

Eye Problems

  • Canine Multi-focal Retinopathy (CMR), also known as Retinal Dysplasia/Retinopathy – Abnormal development of the retina present at birth and recognized to have three forms: folds, geographic, and detachment. A Mastiff with folds will currently pass CERF and the folds may disappear over time, while the geographic and detached forms may cause loss of vision or blindness. There is a DNA test available though OptiGen for CMR in Mastiffs.
  • Cataract – Lens opacity that may affect one or both eyes and some forms may cause blindness.
  • Distichiasis – Eyelashes abnormally located in the eyelid margin which may cause ocular irritation.
  • Ectropion – Conformational eyelid defect, which may cause ocular irritation due to exposure.
  • Entropion – Conformational defect where eyelid margins invert or roll inward, toward the eye causing eyelashes and hair to rub against the cornea which may result in ocular irritation and pain.
    Macroblepharon – Abnormally large eyelid opening; may lead to secondary conditions associated with corneal exposure.
  • Persistent Pupillary Membranes (PPM) – Persistent blood vessel remnants in the anterior chamber of the eye which fail to regress normally in the neonatal period.
  • Progressive Retinal Atrophy (PRA) – Degenerative disease of the retinal visual cells which leads to blindness. In Mastiffs the age at which PRA can be detected varies from as young as 6 months to as late as 42 months. Typically Mastiffs with PRA go blind gradually, first loosing their night vision and then their day vision. Many do not go completely blind until they are 8 years old or older. There is a DNA test available through OptiGen for PRA in Mastiffs.

Orthopedic / Structural / Joint Problems

  • Anterior Cruciate Ligament (ACL) Rupture – The knee along with the external support (i.e., collateral leg) has two ligaments inside the joint that help prevent forward movement (i.e., cruciate). Insult/injury can cause this ligament to rupture and result in acute lameness (not want to bear weight) on the limb.
  • Degenerative Myelopathy (DM) – This is a progressive, degenerative, late onset disease of the spinal cord seen in older dogs. The symptoms usually begin with hind end weakness, lack of coordination and shuffling or dragging of the rear feet. There is a DNA test for DM through OFA
  • Elbow Dysplasia – Elbow dysplasia encompasses several different conditions, all of which are indicative of abnormally formed or fused elbow joints and all can cause lameness and pain.
  • Fragmented Coronoid Process (FCP) – This form of elbow dysplasia is generally the most difficult to treat if the fragments are actually loose in the joint.
  • Osteochrondritis Dissecans (OCD) – A defect in the joint cartilage overlaying or attaching to the bone. OCD most commonly occurs in the elbows, shoulders, hocks and stifles.
  • Ununited Anconeal Process (UAP) – In giant breeds such as Mastiffs the Anconeal Process (a small projection of bone on the ulna, the longer of the two bones of the forearm) can close later than in smaller breeds, often as late as one year of age or older.
  • Hip Dysplasia – Hip dysplasia is a painful condition caused by abnormally formed hips. The animal may become lame in the hind quarters due to the pain associated with the degeneration of the hips.
  • Hypertrophic Osteodystrophy (HOD) – A developmental disorder that manifests with toes turning in or out, roached toplines, pinched rears, and in advanced stages fever, lethargy, pain in joints, inability to stand or function. This is a problem of intake in calories versus output of energy – too many calories consumed and/or unbalanced diet disrupted by supplementing.
  • Panosteitis (Pano or Wandering Lameness) – A developmental problem that affects the long bones during rapid growth periods typically between 6-16 months of age. The exact cause is unknown although genetics, diet, stress, infection, and metabolic or autoimmune problems have been suspected. Lameness can occur in one limb or over time in all limbs. It often is intermittent affecting one leg then another and back again. It is self-limiting and spontaneously disappears.
  • Spondylosis – is a degenerative disease that causes excessive bone production of osteophytes along the spinal vertebrae which can cause lameness. In advanced cases the vertebrae can fuse together. In many cases there are no clinical symptoms, but the acute expression of the disease such as lameness, severe pain and disabilities are often seen in adults and older Mastiffs.
  • Wobblers Syndrome – Cervical Vertebral Instability (CVI) is caused by pressure and pinching of the cervical spinal cord and the nerves in the neck due to ligament problems and/or vertebrae malformation. The compression on the spinal cord in the neck may cause the Mastiff to stand and move abnormally. This is believed to be an inherited genetic disorder with environmental influence. Rapid growth and nutrition may influence the expression of the disease.

Other Health Issues

  • Allergies – Some Mastiffs have allergies to certain foods, pollens, etc. Allergies are due to autoimmune problems and since they often run in certain lines they are believed to be inherited.
  • Cancer – Most forms of cancer have been diagnosed in some members of the breed. Cancer can be hereditary while others occur spontaneously or even due to environmental toxins. Although there are several forms of cancer found in Mastiffs, the most common types are: Osteosarcoma (Bone Cancer), Lymphoma, Hemangiosarcoma, Mast Cell Tumors, Squamous Cell Tumors, & Breast Cancer. Today there are advanced medical treatment options such as radiation, chemotherapy and medications to reduce the size of the tumors and offer pain management to help maintain a good quality of life.
  • Cystinuria – An inherited metabolic disease caused by a defective kidney transporter for cystine and some other amino acids. Because cystine readily precipitates in acid urine, crystals and later calculi (stones) can form in the kidney and bladder. Cystinuria in Mastiffs primarily affects males and can result in serious illness and may be life threatening.
    Epilepsy – A seizure disorder which can have multiple causes. The age of onset of the inherited form is normally around 6 months to 5 years of age. Epilepsy is often difficult to treat successfully in Mastiffs and other large breeds.
  • Gastric Dilation, Torsion, Volvulus (Bloat) – Bloat is a hideous killer of giant breed animals, and Mastiffs are no exception. Without warning, the stomach fills with air (dilation), can twist 180 degrees (torsion) on its long axis, or more than 180 degrees (volvulus) thereby cutting off blood and oxygen to vital organs. Bloat can be primary or secondary, caused by emotional or physical stress, improper nutrition or feeding habits, guzzling water, inappropriate exercise, as well as other causes that we do not understand. Every Mastiff owner needs to familiarize themselves with bloat symptoms and have a plan of action to get the animal to an emergency medical facility at the onset of the first symptom. A dog that is bloating often has approximately 3 hours to live without medical intervention.
  • Heart Disease – The most common heart problems in Mastiffs are cardiomyopathy, aortic stenosis and mitral valve dysplasia. Early detection and treatment are essential for a good prognosis. Some mastiffs have heart murmurs that are mild and not a cause for concern. If a heart murmur is detected it is essential to have it checked to see if it is an “innocent” murmur or a serious problem.
  • Hypothyroidism – Hypothyroidism is the result of an abnormally functioning thyroid gland resulting in a lower than normal level of thyroid hormone. This lack of thyroid hormone can have serious health consequences including coat and skin problems, intolerance to cold, weight gain or loss, infertility, sudden aggression, and immune system malfunctions. The inherited form is autoimmune thyroiditis where the body’s own immune system attacks and destroys the thyroid gland or reduces its function. Autoimmune thyroiditis is diagnosed by measuring the FT4D, cTSH & TgAA. Acquired hypothyroidism can be caused by various problems such as stress for long periods of time, poor nutrition, prolonged infections, and chemical agents.
  • Reproductive Issues – There are several reproductive problems that can affect Mastiffs and it is encouraged that you research this area if you plan to breed. Some of the most common are pyometria (uterine infection), cryptorchidism (undescended testicles), failure to conceive, and vaginal hyperplasia.
  • von Willebrand’s Disease (vWD) – An abnormal bleeding disorder due to a lack of normal clotting. An animal’s life can be threatened by bleeding due to an injury, or during spaying/neutering or any other condition resulting in bleeding.