Guard and defense. The breed is closely related to the seasonal moving in the livestock, and especially the Merino livestock which he already accompanied at the time of the “Mesta” (association, in the Middle-age, of breeders of the wandering herds) by defending them from wolves and other predators, all along their journey from one location to another and on the grazing pastures, in all seasons and sites. Actually he accompanies numerous herds, whether sedentary or wandering by fulfilling his ancestral task. He performs in the same way the function of guard and protection of farms, people and properties in general.

It is a dog of great size, hypermetic (taller than average), of medium proportions and of sub-long line structure. Well balanced, very powerful and muscular. Compact bone structure. Massive head and a body covered with a semi-long coat. Most important are balance and functional harmony in the dog standing as well as on the move. His bark is raucous, low-pitched and deep, very sonorous, audible from a considerable distance.
Important proportions: The length of the body exceeds the height at the withers. The relation between the length of skull and that of the muzzle must be 3/2.

He is a very intelligent dog, not without beauty, whose expression manifests both these qualities. Rustic, affectionate, kind and noble, he is very determined when facing dangerous animals and in front of strangers, especially when he has the opportunity to defend and protect farms or cattle. In his behaviour, one can see it is a dog sure of himself, determining his strength because he is aware of his enormous power.

Big, strong and shaped like a truncated pyramid with broad basis. The whole of the skull and muzzle, seen from above, must be square and well linked, without a very marked diminution of width between the base of the muzzle and the temporal bones. The facio-cranial axes are moderately divergent.
Skull: Broad, strong, profile sub-convex. The width of the skull should be equal or superior to its length. Frontal sinus accentuated. Occipital crest marked.
Stop: Slightly sloping, not very accentuated.
Nose: Black wet, big and broad.
Muzzle: Straight nasal bridge. Seen from above, the muzzle appears moderately rectangular, tapering gradually towards the nose, but still keeping an appreciable width. In no case should it be pointed.
Lips: The upper lip largely covering the lower lip; the lower lip with slack mucous membranes forms a very loose labial commissure (corner of mouth). The mucous membranes must be black.

Small in comparison with the skull, almond shaped, preferably dark, of hazel colour. The look is attentive, noble, soft and intelligent, very hard in front of strangers. Eyelids of thick tissue, with black pigmentation. The lower lid allows a part of the conjunctiva to be seen.

Of medium size and hanging; triangular shape and flat. Attached above the eye-line. At rest, hanging close to the cheeks, without being too close to the skull. In attention, they come away from the cheeks and are partially pricked in the back part of their top third. They must not be cropped.

Scissor bite. Teeth white, solid and sound. Big, pointed canines assuring a good hold of prey. Molars solid and powerful. Incisors rather small. All premolars should be present. Palate black, with well marked ridges.

Trunk shaped, broad, solid, muscled, flexible. Skin thick and loose. Double dewlap amply developed.

Forelegs perfectly vertical, straight and parallel seem from the front. The length of the forearm should be triple of that of the pastern (metacarpus). Bone structure solid, with powerful metacarpus.
Shoulder: Oblique, very muscular, longer than the forearm. The scapular-humeral angle is near 100 degrees.
Upper arm: Strong, of similar length to that of the shoulder blade.
Elbows: Close to the thorax. Humeral-radial angle close to 125 degrees.
Forearm: Solid, with vertical bone.
Pastern: Seen from the side slightly oblique. It is practically in the extension of the forearm. Solid bone.

Rectangular. Stocky and robust, showing great power, yet supple and agile.
Chest: Broad, deep muscled and powerful. The point of the sternum marked. Ribs with wide intercostal spaces, rounded, not flat. The minimum thoracic perimeter exceeds by about 1/3 the height at the withers.
Topline: Straight, horizontal including while on the move.
Withers: Well marked.
Back: Powerful, muscled.
Loin: Long, broad and powerful. Its dimensions decreasing down towards the flank.
Croup: Broad and solid. Its inclination to the horizontal is of some 45 degrees. The height at the croup is equal to the height at the withers.
Belly and flank: Belly very moderately tucked up, the flank let down and very ample.
Skin: Elastic, thick abundant and pink coloured with darker pigmented areas. All mucous membranes must be black.

Powerful and muscular. Lateral view: adequate angulations in form of big articular angles. Correct limbs, seen from behind and from the side. Hocks not deviated, they must be capable of transmitting impulsion of the dog with ease, strength and elegance.
Thighs: Solid and muscular, Femoral-coxal angle nearly 100 degrees.
Stifle: Femoral-tibial angle nearly 120 degrees.
Lower thigh: Long, muscular, solid bone structure.
Hocks: The open angle of the hocks is nearly 130 degrees.
Metatarsus: Well marked, with the Achilles tendon clearly visible.

Forefeet: Cat feet. Toes close, solid and well arched. Nails and pads strong and resistant. Interdigital membranes of medium development and covered with hair.
Hind feet: Cat feet, very slightly oval. Dewclaws present or not, may be single or double. Their removal is permitted.

Very thick at its root and set at medium height. Solid, supple and covered with hair longer than that of the rest of the body. At rest it is carried low, distinctly reaching the hock; sometimes forms a curve in its last quarter. When the dog is moving or animated, he will raise it in a sabre fashion, with a curve at its tip, but never curved in all its length nor carried over the croup.

The preferred gait is a trot, which must be harmonious, powerful and without tendency towards lateral rolling. No ambling.

Dense, thick, medium length, smooth, distributed all over the body down to the interdigital spaces. Two types of coat are distinguished; covering coat on the back and another protecting type on the ribcage and the flanks. Shorter on the legs, longer and silky on the tail.

Indifferent. The colours most appreciated being self-coloured like yellow, fawn, red, black, wolf colour and deer colour. Also appreciated are the combined colours like brindle, parti-coloured or dogs with a white collar.

There is no upper limit of size, the subjects of greatest size being the ones most highly thought after providing they are of harmonious proportions.

Height at the withers:
Minimum size for males; 77 cm
Minimum size for bitches 72 cm

It is desirable that these measurements be amply exceeded; the size in males should be over 80 cm, and in females over 75cm.

Any departure from the foregoing points should be considered a fault and the seriousness with which the fault should be regarded should be in exact proportion to its degree and its effect upon the health and welfare of the dog.

Slight Faults:
Roman nose, without excess.
Pincer bite, lack of any premolar.
Weak lumber-dorsal line, having lost its straight line and undulating on the move.
Pasterns, rear pasterns and feet weak, without excess.
Timidity, not too accentuated.

Serious faults:
Exaggerated frail or lethargic appearance.
Pointed muzzle.
Moderately overshot mouth.
Absence of various molars or canines, not from traumatic origin.
Excessive entropion or ectropion.
Cropping of the ears.
Tail resting on the croup.
Sway back.
Height at the croup noticeably superior to the height at the withers.
Docking of the tail.
Incorrect legs, weak or deviated.
Cow-hocked either standing or moving
Lateral displacement of the legs when moving.
Wavy coat, curly or excessive length.
Unbalanced temperament, excessive timidity or exaggerated aggressiveness.

Eliminating faults:
Aggressive or overly shy.
Nose or mucous membranes depigmented.
Split nose.
Undershot mouth of whatever degree; excessively overshot.
Light eyes.
Any dog showing physical or behavioural abnormalities shall be disqualified.

N.B. Male animals should have two apparently normal testicles fully descended into the scrotum.