Pyrenean Mastiff

Stuart Fitzgerald
Dr Stuart Fitzgerald (MVB MANZCVS, University College Dublin)
Photo of adult Pyrenean Mastiff
TBjornstad /

The Pyrenean Mastiff is an extremely large breed of dog that originated in the Spanish kingdom of Aragon in the Middle Ages. Over the following centuries, it roamed the Pyrenees with flocks of sheep, living among them and their herders as a guardian against the many wolves and bears found in the region throughout this time. Its calm and passive demeanour belie its watchful and protective instincts, and while it is a big teddy bear with its family, it becomes a ferocious protector when the circumstances demand. Despite its innate suspicion of strangers, it is not aggressive unless provoked, and it is particularly gentle with children – although its sheer size can cause problems for youngsters who are unsteady on their feet.

The Pyrenean Mastiff is not highly energetic, but does need a good deal of outdoor space: its migratory past means it is not content to live within the confines of a house at all times. Its thick coat sheds quite heavily, and needs regular grooming to prevent mats and clumps forming. Because the breed has only recently been recognised outside its native Spain, it has not been intensively bred, and so genetic problems are quite uncommon. Despite its large size, it is a healthy breed, with an average life expectancy of 10–12 years.

About & History

Spain boasts not one, but two mastiffs, with the Spanish Mastiff and the Pyrenean Mastiff being long separated, despite both working as flock guardians for many centuries. Legend has it that the original forebears of both breeds were brought to the country by Phoenician traders almost 3000 years ago. This is impossible to prove, but certainly both are members of the molosser family of dogs, meaning their roots are likely to go back at least 2000 years. Like other molossers, they found employment as guard dogs, as their heavy build and huge heads were a natural fit for the role.


While the Spanish Mastiff was to be found working livestock in the flat central region of modern Spain, known as the Castilla, until modern times, the Pyrenean was native to the northern Kingdom of Aragon – a mountainous area. The river Ebro, running diagonally across the northeast of Spain, is said to have always marked a border between the breeds. Though easily confused on the basis of their names, there is no connection between the Pyrenean Mastiff and the Pyrenean Mountain Dog.

The Aragonians were sheep farmers, with herds that grazed the foothills of the Pyrenees. As well as guarding sheep, Pyrenean Mastiffs lived in homes and on farms, protecting their “flock” of humans and their property. When working in the fields, the dogs would be allowed to wander among the sheep, who would welcome the reassurance of these imposing protectors. The Mastiffs often wore heavy collars of iron, leather, and protruding spikes to grant them some protection when facing the sheep’s main predators: wolves and bears.

Due to the large numbers of these animals in the wild, there was no shortage of work for the Pyrenean Mastiff; however, large-scale eradication of the predators in the 1930s meant that they no longer posed a serious threat to agriculture, and the breed’s enormous size and correspondingly large appetite made it an expensive luxury to maintain.


As a result, Pyrenean Mastiff numbers plummeted, and it is only thanks to the work of a few dedicated people that it survived the hardships of post-Civil War Spain. It appears that very of these magnificent dogs were to be found outside of their homeland before the 1980s, and although the Kennel Club granted the breed recognition in 2001, it remains on the US Foundation Stock register, and is still awaiting full pedigree status.


Pyrenean Mastiff Large Photo

This very large dog is extremely strong and muscular, but also modestly proportioned, carrying its weight on a large frame. Despite its size, it does not come across as sluggish or slothful, and is unexpectedly light and easy in its movement. It has a large, moderately long head, with the skull being just slightly longer than the length of the muzzle, which is almost as wide at its base as the crown of the head. The crown itself is slightly domed, and dips to a very subtle stop at the forehead.


The upper lip is not overly generous compared with other mastiff breeds, though the lower lip is a little slack, revealing black gums beneath. The nose is always black in this breed.

The mouth should have a perfect bite, with very large teeth – the sort one could imagine tackling a bear! The eyes are small, almond-shaped, and hazel in colour. The ears are triangular, medium in size, and hang flat to the head.


The broad neck is another feature adapted to the rigors of life as a guardian, with loose, thick skin forming a double dewlap to withstand bites and tears. The body is rectangular and robust, with a straight, strong topline and a deep, broad chest. The belly is moderately tucked up. The loins are particularly strong and well-muscled, and the rump is wide and powerful, sloping at a 45-degree angle.

The tail is set on high, and is thick, strong, and flexible. It carries a long plume of hair, and hangs down to the hocks when at rest, though it can be elevated when the dog is excited. When viewed from the front or rear, it is important the Pyrenean Mastiff has limbs that are vertical and true in motion. They are moderately angulated, heavily boned and muscular. The paws are described as cat-like, though they are more reminiscent of those of a tiger rather than a domestic moggy!


The coat is dense, thick, and moderately long, with longer hairs covering the shoulders, neck, underside of the belly, backs of the legs, and tail. The hair is coarse and bristly, though somewhat softer in the plumed areas. The predominant coat colour is always white, with a well-defined darker mask a consistent facial feature. The ears are always spotted with colour, and there may be irregular patches of matching colour elsewhere on the body. These colours include:

  • Medium Grey
  • Golden
  • Brown
  • Black
  • Grey-Silver
  • Light Beige
  • Sandy
  • Marbled


Great size is encouraged in the breed, and so there are no upper limits set by the breed standard. Instead, males must be at least 81 cm (32 in) tall at the withers, and females should exceed 75 cm (30 in). Body weights can vary enormously, from 70–86 kg (154–189 lb) for females to 80–100 kg (176–220 lb) for males.

Character & Temperament

The Pyrenean Mastiff is a calm, confident, and even-tempered dog. Docile with its owners and gentle with children, it is difficult to irritate. Most tolerate the company of other dogs very well, and will lounge around while being pounced on and nibbled by smaller canine members of the family.

They are aware of their enormous strength, and so rarely use it. However, if challenged, and particularly if they feel their family is threatened, they become an entirely different animal – fearless, intimidating, and aggressive when appropriate. Homes with a Pyrenean Mastiff are unlikely to be high on any burglar’s list of targets.


The breed is reasonably easy to train, as long as lessons are introduced from a young age. Pyreneans can be quite headstrong, and can certainly take advantage of an inexperienced owner, playing on their cuteness as puppies to push the boundaries of acceptable behaviour. It is very important that they realise their owners’ dominant position in the family pack, and respect and respond to commands. Given its protective nature, the basic commands of “sit”, “cease”, and “stay” are essential parts of any Pyrenean’s repertoire.


Though the breed is generally healthy, the Kennel Club does advise that prospective owners research their breeders carefully, and that all Pyrenean Mastiffs should be hip scored and undergo careful eye examination by a specialist veterinary ophthalmologist.


The breed standard specifies that the Pyrenean’s eyelids should be close-fitting to the eye, a feature that can sometimes cause problems. Occasionally, pups will be born with abnormally everted eyelids that are prone to irritation and infection due to chronic exposure. If problematic, ectropion can be surgically corrected.


More commonly seen than ectropion, entropion represents the opposite problem – inward scrolling of the eyelids, again, usually first noticed in puppyhood. Because the outer surface of the lid is covered in hair, when in contact with the eye’s delicate and sensitive surface it causes chronic discomfort and inflammation, and if left uncorrected can cause permanent scarring of the cornea. Surgery is required to evert the affected lid or lids, but will need to be staged or delayed until adulthood.

Gastric Dilatation & Volvulus

Like other large, deep-chested breeds, Pyrenean Mastiff can experience a sudden twisting of the stomach, which results in the organ swelling massively. The first signs of the problem may be enormous abdominal enlargement and collapse, and emergency veterinary attention is required for life-saving surgery. Feeding a single large meal each day and exercising after feeding are predisposing factors that should be avoided in any large breed dog.

Hip Dysplasia

A common cause of lameness in many large breed dogs, this developmental disorder may be seen to affect one or both hindlimbs sometime between 5 and 14 months of age. Though the signs of stiffness after lying down, lameness, and pain on hip extension are suggestive, diagnosis requires x-ray examination. Though many young dogs appear to recover from the problem in adulthood, it is one of the major causes of early onset osteoarthritis in middle age.

Inflammatory Bowel Disease

Although this is not a common disorder, Pyrenean Mastiffs do seem to be predisposed to developing chronic diarrhoea and weight loss as a result of an inflamed gut. The cause is never determined in most cases, but its response to hypoallergenic foods and immunosuppressive medications strongly suggests an autoimmune basis to the illness.


Rapidly growing dogs of any large breed can develop this condition, which causes lameness and pain on manipulation of the bones of the limbs. The lameness is often “shifting” in nature, meaning it may affect different limbs over a relatively short course of time. X-rays of pups with panosteitis reveal marked inflammation in the long bones. This generally responds very favourably to the use of anti-inflammatory medications as needed, and affected dogs outgrow the problem before 18 months of age

Exercise and Activity Levels

The Pyrenean Mastiff is not a very energetic breed, though it does need space. Having been bred to cover vast swathes of mountainside at a leisurely pace, its preferred mode of exercise is a gentle stroll around a large garden, with the occasional burst of energy on sighting a stranger in the distance. Like any dog, it will enjoy lead walking with its owner, although around half an hour a day should suffice for most.


The Pyrenean’s thick coat sheds reasonably heavily all year round, but it does have two particularly heavy moults in spring and autumn, when it will lose large clumps of hair. Moulting can be minimised, but never prevented, by good-quality food and regular brushing. For most of the year, brushing or combing should be done every other day, while daily grooming is ideal when the dog is undergoing one of the heavy moults.

As for any breed, daily tooth brushing using a dog-specific toothpaste is a great help in preventing dental disease. Nails should be clipped whenever they can be heard to scrape or click on the floor. The thickness of the Pyrenean Mastiff’s nails means that only a very robust clipper should be used to avoid splits and cracks in the nail surface.

Famous Pyrenean Mastiffs

The breed keeps a low profile, although several media reports in the past have mistaken the smaller Pyrenean Mountain Dog for the Mastiff.


Perhaps because they have only been bred outside of Spain relatively recently, I have never encountered a Pyrenean Mastiff cross in my professional practice.

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