In character and function, the Spanish Mastin is a classic LGD or Livestock Guardian Dog and is very similar in many ways to his cousin; the Anatolian Shepherd Dog. Please note that like most LGD breeds, Spanish Mastiffs are in general, quite independent by nature, not very affectionate dogs in the same way a Golden Retriever, Poodle or Boxer (they could care less most of the time whether they are being petted/cuddled or not and often don't give much in return of affection) and are rather aloof, even to their owners. They are also dignified, noble and not overly demonstrative. Females can be even more aloof and less affectionate than males and the males do tend to be a bit sweeter tempered. However, females are a bit more cunning and better thinkers. However, in spite of that, these dogs are loyal and really do love you, will sacrifice his/her own life to protect you, your family or your livestock, when necessary. They want to be close to you at all times and follow you EVERYWHERE. They are highly territorial and need some re-assurance from the owner when visitors come on to your home so they know they are no threat, unwelcome guests will have absolutely no chance of stepping onto your property. However, being independent-minded, they may not take your orders and refuse to let a stranger in your home, regardless if the person (s) is a threat or not. Some individuals seem to have the ability to distinguish between a friend and foe. Unlike some LGDs such as the Caucasian Ovtcharka and South Russian Ovtcharka, the Mastin always gives warning with much threatening, deep barking and growling, which shows clearly their intentions, before going into action, there are no unprovoked attacks. They also have a somewhat lower "trigger" in that they do not react as quickly to stimuli and are also more laid back than CO and SRO, which makes them easier guardian dogs to own. Although the Mastin may appear lazy and even slothful at times, they are always watchful and alert to everything that goes on around them and always ready to protect/defend.

They seem to become even more alert and defensive at night than in the daytime and darkness seems to sharpen their senses (probably because predators in Spain tend to be most active at night). Can be surprisingly quick and agile in spite of breed's massive size and bulk. They will often choose the highest spot they can find (such as a small hill, etc.) on your property, from which to survey their domain for potential danger. In general, the Spanish Mastiff is very mistrustful of strangers; both human and canine. Any degree of shyness or fearfulness is to be discouraged in the breed, as shall overly aggressive or mentally unsteady dogs. Mastines possessing such traits should be excluded from the breeding program. A good Mastin should be a strong, utterly fearless, self-confident and stable minded dog. Extensive socializing and training in early puppy hood (during the critical stage between 3 and 12 weeks of age) is a must if you want your Mastin to become reliable out in public and around other dogs. However, when Podero (my own Spanish Mastiff) was a young pup, he didn't have any socializing at all until I adopted him at 16 months of age and yet he is very reliable out in public and good with other dogs and animals. They are very intelligent and are capable of making their own decisions and solving problems on their own, especially females. Although smart dogs, the Mastin can seem stubborn (though in a rather sweet way) and is not the easiest breed to obedience train, due to their independent nature. They learn quickly, but may only respond to a command the first time and then become bored of it and not want to respond to it any longer. They also have "selective deafness" tendencies; in that may only respond to you on their own terms and can be slow to respond to a command, especially if they don't feel like doing it. Do not expect this breed to become as tractable/reliable in obedience as a German Shepherd, Border Collie or Labrador Retriever. Clicker training with treats (these dogs are usually quite food-motivated) and a loving, consistent approach will have the best results on the Mastin. Avoid repeating the same commands too often during training sessions, or the dog is likely to become bored of it.

Do not pressure or force the Mastin. Training advice from someone who understands LGD temperament is a very wise idea. These characteristics are due to the fact that the Spanish Mastiff, like most LGDs, was bred to work independently from, rather than along with their human owners. These are generally dominant dogs and should have an owner who is consistent and knows how to display a strong leadership, becomes submissive to owners once the Alpha role has been established and is usually submissive towards their "pack" members (the flock or herd it lives with). A rough approach will bring undesirable characteristics to the surface. The Mastin always sticks close to his flock or herd, keeping wolves and other predators at bay. They do not chase predators away that approach, but rather warns them with fierce, deep barking and growling to keep their distance. However if the enemy decides not to back down, the Mastin will fearlessly and determinedly fight that predator/intruder (be it man or beast), to the death to defend what he calls his own. In Spain, shepherds often put traditional Carlancas (spiked collars) on their Spanish Mastiffs to protect their neck incase they get into a fight with a wolf while defending their flock/herd. They are and were never used to herd livestock, only to guard them. They have also been used as draft dogs; pulling heavy carts over difficult terrain and with excellent results for guarding property, such as Spanish vineyards, fruit orchards, homes, large estates and in the past during Spanish civil war, for guarding munitions. They are relatively calm dogs when adults, but as with all breeds they can be rather "turbulent" (energetic) at times when young, but once mature they are quite low-keyed and calm dogs. The Mastin like many large/giant breed dog, is very slow to mature, especially the males which do not reach their prime until 2 1/2 to 3 years of age. They are generally very tolerant of and patient with children, pets and all other family members, but must be carefully introduced to new comers. Being so big and strong they can unintentionally hurt a young child, especially young dogs have a tendency to play rough. They can be very aggressive towards unfamiliar dogs, especially to ones of the same sex and they certainly will NOT take kindly to strange dogs that trespass on to their territory. The Mastin is also very assertive and will not back down if challenged or dominated by another dog. In general, they do not enjoy chasing a ball, stick, etc. or games of fetch, due to their relatively low prey instinct, although they love being chased by you, games of tug-a-war and wrestling.