Official ICCF Breed Standard Description
Brief Historical Summary
The Mastiff belongs to one of the most ancient Molosser breeds, descending from massive guardian dogs of Mesopotamia and ancient Rome. These dogs were used to guard settlements, protect warriors and accompany armies in military campaigns. During the Middle Ages, Mastiffs gained great popularity in England, where they were valued as reliable guardians of estates, castles and farms. The breed developed under the influence of heavy working dogs known for their massiveness, courage and endurance. In the 19th–20th centuries, systematic breeding began, aimed at stabilizing strong bone structure, a steady temperament and an expressive breed type. Today the Mastiff is known as a calm, powerful and noble breed that has preserved its traditional guarding qualities.
General Appearance
The Mastiff is an extremely large, powerful and imposing dog with a massive build, strong bone and well-developed musculature. The format is slightly elongated; the body is deep and voluminous with a broad chest and strong back. The overall impression is strength, calm confidence and dignified solidity. The head is large and square with a pronounced stop; the nose is broad, the muzzle wide. Eyes are medium-sized with a warm expression. Ears are small and close-fitting. Limbs are straight, strong and stable, with round feet. The tail is thick at the base and reaches the hock. Movement is even, free and powerful, with strong rear drive and a stable topline.
Important Proportions
The Mastiff’s proportions emphasize balance between massiveness and functionality. Height at the withers is considerable, yet the dog remains proportional and stable. Body length slightly exceeds height, giving a somewhat elongated format. The head must be large but proportionate to the overall size. The muzzle makes up about one-third of the head length and remains broad throughout. The chest is deep, descending below the elbow and providing great lung capacity. Broad shoulders and strong bone are essential breed features. Limbs must be straight and sturdy with well-developed joints. The tail must fit the overall balance, neither excessively long nor short.
Behavior and Temperament
The Mastiff is calm, confident and well-balanced, combining natural guarding instincts with gentleness toward the family. It is a reserved breed, not prone to unprovoked aggression, but capable of decisiveness and strength when necessary. The Mastiff is loyal, dependable and emotionally stable, showing patience with children and maintaining composure even in unfamiliar environments. With its natural instinctiveness, it stays attentive to its surroundings but reacts thoughtfully. Training requires consistency, respect and early socialization, allowing the breed’s competent, confident and noble character to fully emerge.
Head
The head is large, broad and voluminous, with pronounced mass typical of Molosser type. The skull is wide between the ears; the planes of skull and muzzle are parallel. The forehead is moderately convex with a distinct but not exaggerated median furrow. Skin forms characteristic wrinkles when alert, without excess. The stop is well defined yet smooth, merging into a wide, deep muzzle. Cheeks are strong but not excessively prominent. Jaws are powerful and square, with a complete set of teeth. The overall shape is imposing yet harmonious, avoiding coarseness or exaggeration. Proportions must match the large body, creating an impression of strength, calmness and confident breed type.
Facial Region
The muzzle is broad, deep and rectangular, retaining full width along its length. The muzzle is about one-third of the head length. The bridge of the nose is straight and broad; the nose itself is large and black with wide nostrils. Lips are thick, well-developed and fleshy; the upper lip covers the lower, forming characteristic flews without excessive drooping. Jaws are powerful, with a preferred scissor or level bite. Skin on the face is tight, with moderate wrinkling allowed when excited. The facial region should emphasize the breed’s expressiveness, blending strength, dignity and calm.
Eyes
Eyes are medium-sized, oval, and widely set, giving a calm and kind expression. They are moderately deep-set, without signs of sunken or bulging eyes. The iris is dark, preferably hazel or dark brown, matching the coat tone. Eyelids are tight; the lower eyelid should not droop excessively. Slight looseness consistent with breed type is allowed, but marked ectropion or entropion is unacceptable. The expression must be soft, attentive, confident and thoughtful. The Mastiff’s look reflects mental stability, absence of unjustified aggression and a high threshold of excitability. Any deviation affecting the typical expression is considered a fault.
Ears
Ears are small, thin, triangular, set high and wide on the skull, hanging close to the sides of the head. Their size must be proportional to the large head, neither too big nor too small. Tips are rounded and directed toward the cheeks. At rest they lie flat; when alert, the base lifts slightly, emphasizing the skull’s width. The inner edge lies close to the head, creating a clean silhouette. Ears set too far back, too large, thick or outward-facing are faults. The ears are usually darker than the coat color. Their appearance should support the expression of calm strength.
Neck
The neck is powerful, muscular and of medium length, blending smoothly into the withers and shoulders. The base is broad and well-developed, highlighting the breed’s massiveness. The topline is slightly arched; the underside shows a distinct dewlap without excess. The neck must support the heavy head while remaining flexible and strong. In movement it stays stable and confident without being carried too high. The neck must combine strength and functionality, allowing free movement of the head and contributing to the breed’s noble outline. Short, overly thick or weak necks disrupt balance and are undesirable.
Body
The body is extremely powerful, deep and broad, conveying strength and stability. The chest is very spacious, wide and descending below the elbow. Ribs are long and well-curved, forming a large thoracic cavity. The back is broad, straight and muscular. The loin is short, strong and slightly arched. The croup is broad, powerful and slightly sloping. The abdomen is moderately tucked. Body lines must be harmonious and proportional to the large size, avoiding looseness. Bone is strong and massive yet balanced, supporting considerable weight. Narrow chest, weak back, softness of body or coarse, disproportionate shapes are unacceptable.
Tail
The tail is thick at the base, tapering gradually, medium in length, reaching the hock or slightly below. Set moderately high, it hangs naturally when relaxed. When moving, it rises to the level of the back or slightly above, without curling or excessive curvature. It must be straight, strong and free of kinks. Coat on the tail is short and dense. The tail must harmonize with the overall format, complementing the breed’s massive and stable outline. Too short, high-set, low-set, overly curved or structurally defective tails are faults. A correct tail supports the Mastiff’s typical, noble appearance.
Forequarters
Forequarters are straight, powerful and well-boned. Shoulders are long, sloping and well attached with strong musculature. Upper arms are powerful with moderate angulation. Elbows are positioned directly under the body, facing backward without turning in or out. Forearms are straight and strong with heavy bone. Pasterns are short and firm with slight incline. Feet are large, round, with thick pads and arched toes. The forequarters must support the dog's heavy mass and provide stability and smooth movement. Weak pasterns, curved forearms, turned elbows, narrow stance or insufficient bone are faults.
Hindquarters
Hindquarters are powerful, broad and strongly muscled, providing strong drive and supporting the heavy body. Thighs are long, very muscular and well defined. Stifles are strong with moderate angulation. Lower thighs are broad and solid. Hocks are strong, low-set and straight, without weakness or rotation. Metatarsi are short and vertical. Feet are large, compact and thick-padded. Rear structure must provide powerful, steady and typical movement. Cow-hocked, bow-legged, weak joints, extreme or insufficient angles and narrow or close-set limbs are faults.
Gait and Movement
Movement is powerful, free and steady with good reach and strong rear drive. At the walk the dog moves confidently with a level topline. At the trot movement is straight, without body roll, with good front extension and strong propulsion from the rear. All movement must be harmonious and balanced, reflecting correct bone and ligament structure. The Mastiff should not move stiffly or heavily; massiveness must not hinder functionality. Toe-in, toe-out, high front lift, short steps, weak rear or instability are faults. Movement must confirm the breed’s strength and calm confidence.
Coat
The coat is short, dense and close-lying, with a coarse texture. The undercoat is well developed, especially in cold weather, providing protection. The outer coat is straight, medium in thickness, without waves or curls. Coat length is uniform, with slightly denser hair on the neck and shoulders. The skin is thick and elastic with moderate folds on the head and neck typical for the breed, but not excessive. Coat should appear clean, healthy and tight. Too soft, long, sparse, wavy coat, absence of undercoat or signs of poor condition are faults.
Permissible Colors
Permitted colors include fawn, apricot and brindle. Fawn and apricot shades may range from light to rich tones. Brindle features dark stripes on a lighter background. All colors require a black mask, characteristic of the breed. Ears should preferably be darker. A small white marking on the chest is allowed but its absence is preferred. White on other parts, diluted masks or lack of mask are undesirable. Color must be clean, saturated and even, emphasizing strength and nobility. Non-standard colors are disallowed.
Size
The Mastiff is among the largest dog breeds, and its size is an essential part of type. Males typically exceed 75 cm at the withers; females reach around 70 cm or more. Weight is substantial, but the dog must remain functional, avoiding excessive heaviness. Harmony of construction is more important than absolute measurements: the body must be powerful, deep and proportional to long limbs and a large head. Bone must be very strong, musculature developed but not coarse. Too light type, insufficient height, weak bone or excessive mass hindering movement are faults. Size must enhance the impression of strength, nobility and stability.
Faults
Faults include deviations affecting functionality, expression or balance. Weak bone, narrow chest, loose body, insufficient musculature or signs of exhaustion are serious issues. Weak pasterns, turned elbows, weak hocks, incorrect limb angles or poor bone quality are faults. Coarse head, excessive wrinkling, weak mask, light eyes or incorrect ears reduce type. Large white patches are faults. Any traits distorting the breed’s expression of calm strength are considered faults of varying severity.
Disqualifying Faults
Disqualifying faults include traits that fundamentally violate breed type or functionality. Unprovoked aggression, panic-like fear or unstable temperament eliminate a dog from breeding. Severe bite faults, missing multiple teeth, jaw deformities or pronounced head abnormalities are unacceptable. Blue or split eyes, severe entropion or ectropion disqualify. Absence of black mask, white markings in prohibited areas and non-standard colors are disqualifying. Cryptorchidism, docked tail, severe limb deformities, paralysis or coordination defects are disqualifying faults. Any indicators compromising health or true breed origin are grounds for exclusion.
Important Notes
The Mastiff combines impressive size with a calm temperament; evaluation must consider natural massiveness and structural features. Puppies and young dogs grow unevenly, and temporary disproportions should not be judged harshly if functionality is unaffected. Adult Mastiffs move smoothly and steadily, without sudden or rapid motion, which is typical for the breed. Moderate skin folds on head and neck are permissible, but excess is incorrect. Particular attention is given to mental stability, confidence and absence of unwarranted aggression. Assessment must consider health, functionality and breed type as a whole.
Conclusion
The Mastiff is an ancient and majestic breed, combining impressive power, calm disposition and a steady character. Its type was shaped over centuries by the selection of working dogs bred for guarding and protection. The modern Mastiff retains these qualities: confidence, balance, devotion to family and the ability to act decisively when needed. Its appearance should harmonize massive structure, strong bone, expressive head and stable movement. The breed requires respectful handling, early socialization and attentive care to fully reveal its qualities. A correct Mastiff embodies strength, nobility and calm — an ideal guardian and family companion.
