MOLOSSO PRESA MAYO
BREED STANDARD

GENERAL APPEARANCE

The Molosso Presa Mayo is a large, powerful and athletic molosser, combining substantial bone and muscle with strength, agility and functional movement.

The head should be large and imposing, with a broad, powerful body, deep chest and strongly developed musculature. Despite its considerable substance, the dog should never appear cumbersome, excessively heavy or incapable of athletic movement.

The overall impression should be of a serious, physically capable working-type molosser — powerful, confident and imposing while remaining balanced, mobile and functional.

Strength and substance should come from correct construction, bone and muscle, not excessive weight or exaggeration.

HISTORY & ORGINAL PURPOSE

The Molosso Presa Mayo is a modern American breed-development project created by Chad Mayo, rather than an ancient established molosser breed. Early published material described the aim as producing a powerful, athletic and functional molosser-type dog with strong working ability.

Published accounts of the early project consistently identify English Bull Terrier among its foundations, with Presa Canario and American Bully also commonly reported. However, accounts of the exact foundation crosses differ, reflecting the breed’s relatively recent and developing history.

Bullbreeds United therefore recognises the Molosso Presa Mayo as a developing modern molosser, with emphasis on preserving its intended combination of power, athleticism, sound construction and working capability rather than exaggeration.

HEAD & MUZZLE

The head is one of the most distinctive features of the Molosso Presa Mayo, showing a clear English Bull Terrier influence rather than the conventional square-headed molosser appearance.

The head should be long, powerful and well filled, with a characteristic curved profile running down towards the nose. There should be strength and width through the skull and muzzle without losing the distinctive shape.

The jaws should be broad and extremely powerful, with a strong, deep muzzle and well-developed cheek and jaw muscles.

The nose should have large, open nostrils, and the overall head must remain functional, allowing unrestricted breathing despite its considerable size and power.

The eyes should be relatively small, well set and expressive, complementing the distinctive shape of the head without appearing prominent or bulging.

The ears should be small to medium in size, set high and carried naturally, contributing to an alert and powerful expression.

Eyes and ears should remain healthy and functional, with no excessive loose skin or eyelid problems interfering with vision or comfort.

EYES & EARS

MOUTH & BITE

The jaws should be broad, deep and extremely powerful, with strong, well-developed teeth appropriate to the size and strength of the dog.

The bite should be functional and correctly aligned, allowing the dog to grip, eat and use its jaws normally. Excessive undershot or overshot bites, severely misaligned jaws or exposed teeth caused by poor construction are undesirable.

The distinctive head shape should never compromise the function of the mouth or jaw.

SIZE & PROPORTIONS

The Molosso Presa Mayo is a large, heavily built and exceptionally muscular dog, with substantial bone, width and physical presence while retaining athletic ability.

Early published descriptions place the breed at approximately 45–65 cm (18–25.5 inches) at the withers, with adult weights reported at approximately 55–70 kg (121–154 lb).

The body should be powerful, broad and well proportioned, with sufficient leg and correct construction to allow strong, unrestricted movement.

Size and weight should come from bone, structure and muscle rather than excessive body fat, with balance, mobility and function always taking priority.

BODY & CONSTRUCTION

The body should be broad, deep and extremely muscular, with a powerful chest, well-sprung ribs and a strong, substantial frame.

The front should be wide and heavily boned, with strong forelegs capable of supporting the dog’s considerable weight and muscle. The rear should be broad, muscular and well developed, providing powerful drive.

Despite its heavy build, the Molosso Presa Mayo should remain athletic, balanced and mobile, with sufficient leg and correct angulation to move freely.

The dog should give an overall impression of immense physical power without becoming cumbersome or structurally exaggerated.

TAIL

The tail should be natural, strong and proportionate to the dog, balancing the heavily muscled body without interfering with movement.

It should remain mobile and functional, with severe deformity or restriction considered undesirable.

And from here on I'll make sure every section is Molosso Presa Mayo-specific, not generic molosser filler.

COAT & COLOUR

The coat of the Molosso Presa Mayo should be short, smooth and close fitting, clearly showing the dog’s powerful muscular development.

A variety of colours and patterns may occur within the breed, with colour considered secondary to correct type, construction, temperament and function.

The skin and coat should be healthy, with excessive loose skin or exaggeration undesirable.

MOVEMENT

Movement should be powerful, purposeful and surprisingly athletic for a dog of such substantial build.

The Molosso Presa Mayo should move freely with good reach in front and strong drive from the rear, maintaining balance and control without appearing cumbersome.

Heavy muscle and bone must never restrict normal movement. Stiffness, weakness, poor coordination or construction that prevents the dog from moving freely should be considered undesirable.

The dog should demonstrate that its power is functional, not simply visual.

The Molosso Presa Mayo should be confident, stable, alert and self-assured, with the strong character expected of a powerful guardian-type dog.

It should form a strong bond with its handler and family while remaining watchful and naturally reserved with unfamiliar people.

Nervousness, extreme fearfulness, unpredictability or uncontrolled aggression are unacceptable. With a dog of this size and physical power, a stable, manageable temperament is essential.

TEMPERAMENT

Faults should be assessed according to their effect on breed type, health, soundness, temperament and function.

Poor breathing, weak or unsound construction, restricted movement, excessive body weight, structural weakness, poor balance or exaggeration that compromises normal function should be penalised.

The distinctive English Bull Terrier-influenced head shape should remain clearly evident; however, exaggeration of the head must never interfere with breathing, vision, eating or normal jaw function.

MOLOSSO PRESA MAYO
BREED STANDARD

GENERAL APPEARANCE

The Molosso Presa Mayo is a large, powerful and athletic molosser, combining substantial bone and muscle with strength, agility and functional movement.

The head should be large and imposing, with a broad, powerful body, deep chest and strongly developed musculature. Despite its considerable substance, the dog should never appear cumbersome, excessively heavy or incapable of athletic movement.

The overall impression should be of a serious, physically capable working-type molosser — powerful, confident and imposing while remaining balanced, mobile and functional.

Strength and substance should come from correct construction, bone and muscle, not excessive weight or exaggeration.

HISTORY & ORGINAL PURPOSE

The Molosso Presa Mayo is a modern American breed-development project created by Chad Mayo, rather than an ancient established molosser breed. Early published material described the aim as producing a powerful, athletic and functional molosser-type dog with strong working ability.

Published accounts of the early project consistently identify English Bull Terrier among its foundations, with Presa Canario and American Bully also commonly reported. However, accounts of the exact foundation crosses differ, reflecting the breed’s relatively recent and developing history.

Bullbreeds United therefore recognises the Molosso Presa Mayo as a developing modern molosser, with emphasis on preserving its intended combination of power, athleticism, sound construction and working capability rather than exaggeration.

HEAD & MUZZLE

EYES & EARS

MOUTH & BITE

SIZE & PROPORTIONS

The Molosso Presa Mayo is a large, heavily built and exceptionally muscular dog, with substantial bone, width and physical presence while retaining athletic ability.

Early published descriptions place the breed at approximately 45–65 cm (18–25.5 inches) at the withers, with adult weights reported at approximately 55–70 kg (121–154 lb).

The body should be powerful, broad and well proportioned, with sufficient leg and correct construction to allow strong, unrestricted movement.

Size and weight should come from bone, structure and muscle rather than excessive body fat, with balance, mobility and function always taking priority.

BODY & CONSTRUCTION

BODY & CONSTRUCTION

TAIL

COAT & COLOUR

MOVEMENT

Movement should be powerful, purposeful and surprisingly athletic for a dog of such substantial build.

The Molosso Presa Mayo should move freely with good reach in front and strong drive from the rear, maintaining balance and control without appearing cumbersome.

Heavy muscle and bone must never restrict normal movement. Stiffness, weakness, poor coordination or construction that prevents the dog from moving freely should be considered undesirable.

The dog should demonstrate that its power is functional, not simply visual.

The Molosso Presa Mayo should be confident, stable, alert and self-assured, with the strong character expected of a powerful guardian-type dog.

It should form a strong bond with its handler and family while remaining watchful and naturally reserved with unfamiliar people.

Nervousness, extreme fearfulness, unpredictability or uncontrolled aggression are unacceptable. With a dog of this size and physical power, a stable, manageable temperament is essential.

TEMPERAMENT

Faults should be assessed according to their effect on breed type, health, soundness, temperament and function.

Poor breathing, weak or unsound construction, restricted movement, excessive body weight, structural weakness, poor balance or exaggeration that compromises normal function should be penalised.

The distinctive English Bull Terrier-influenced head shape should remain clearly evident; however, exaggeration of the head must never interfere with breathing, vision, eating or normal jaw function.

Extreme fearfulness, instability or uncontrolled aggression are serious faults.

Above all, the Molosso Presa Mayo should remain a powerful, athletic and functional dog with its distinctive breed type clearly preserved.

FAULTS

MOLOSSO PRESA MAYO BREED STANDARD

GENERAL APPEARANCE

​

The Molosso Presa Mayo is a large, powerful and athletic molosser, combining substantial bone and muscle with strength, agility and functional movement.

The head should be large and imposing, with a broad, powerful body, deep chest and strongly developed musculature. Despite its considerable substance, the dog should never appear cumbersome, excessively heavy or incapable of athletic movement.

The overall impression should be of a serious, physically capable working-type molosser — powerful, confident and imposing while remaining balanced, mobile and functional.

Strength and substance should come from correct construction, bone and muscle, not excessive weight or exaggeration.

HISTORY & ORGINAL PURPOSE

​

The Molosso Presa Mayo is a modern American breed-development project created by Chad Mayo, rather than an ancient established molosser breed. Early published material described the aim as producing a powerful, athletic and functional molosser-type dog with strong working ability.

Published accounts of the early project consistently identify English Bull Terrier among its foundations, with Presa Canario and American Bully also commonly reported. However, accounts of the exact foundation crosses differ, reflecting the breed’s relatively recent and developing history.

Bullbreeds United therefore recognises the Molosso Presa Mayo as a developing modern molosser, with emphasis on preserving its intended combination of power, athleticism, sound construction and working capability rather than exaggeration.

HEAD & MUZZLE

​

EYES & EARS

MOUTH & BITE

​

SIZE & PROPORTIONS

​

The Molosso Presa Mayo is a large, heavily built and exceptionally muscular dog, with substantial bone, width and physical presence while retaining athletic ability.

Early published descriptions place the breed at approximately 45–65 cm (18–25.5 inches) at the withers, with adult weights reported at approximately 55–70 kg (121–154 lb).

The body should be powerful, broad and well proportioned, with sufficient leg and correct construction to allow strong, unrestricted movement.

Size and weight should come from bone, structure and muscle rather than excessive body fat, with balance, mobility and function always taking priority.

BODY & CONSTRUCTION

BODY & CONSTRUCTION

TAIL

​

COAT & COLOUR

​

MOVEMENT

​

Movement should be powerful, purposeful and surprisingly athletic for a dog of such substantial build.

The Molosso Presa Mayo should move freely with good reach in front and strong drive from the rear, maintaining balance and control without appearing cumbersome.

Heavy muscle and bone must never restrict normal movement. Stiffness, weakness, poor coordination or construction that prevents the dog from moving freely should be considered undesirable.

The dog should demonstrate that its power is functional, not simply visual.

​

The Molosso Presa Mayo should be confident, stable, alert and self-assured, with the strong character expected of a powerful guardian-type dog.

It should form a strong bond with its handler and family while remaining watchful and naturally reserved with unfamiliar people.

Nervousness, extreme fearfulness, unpredictability or uncontrolled aggression are unacceptable. With a dog of this size and physical power, a stable, manageable temperament is essential.

TEMPERAMENT

​

Faults should be assessed according to their effect on breed type, health, soundness, temperament and function.

Poor breathing, weak or unsound construction, restricted movement, excessive body weight, structural weakness, poor balance or exaggeration that compromises normal function should be penalised.

The distinctive English Bull Terrier-influenced head shape should remain clearly evident; however, exaggeration of the head must never interfere with breathing, vision, eating or normal jaw function.

Extreme fearfulness, instability or uncontrolled aggression are serious faults.

Above all, the Molosso Presa Mayo should remain a powerful, athletic and functional dog with its distinctive breed type clearly preserved.

FAULTS

MOLOSSO PRESA MAYO
BREED STANDARD