Thank you for reaching out to the Mastiff community. She is okay with women but runs from men she isn't familiar with. AGGRESSION TOWARD HUMANS. Discussion in 'General Mastiff Discussion' started by Slick561, Dec 19, 2016. Obviously a dog of this size and power is capable of seriously injuring or killing other animals. However, as with any breed, the Mastiff can become aggressive for varying reasons. My dog, Monty, who is a little over a year and a half has in the past few months, starting in March or April become increasingly aggressive. I've got an English Mastiff I've had since she was a puppy, shes about 3 now. At first when she was younger we thought she'd grow out of the timidness, but she hasn't. I have a 4 year old English mastiff, Mason, most lovable affectionate dog I have ever owned. She has been since we got her. At this time, Mastiffs do not yet appear on most lists of dogs that are on the homeowners insurance blacklist. The strong temperament. I hope you have lots of insurance. Question on English Mastiff aggression? Mastiffs tend to … A typical Mastiff's temperament, by nature, is one of gentle demeanor. The first of these fear periods occurs among puppy Mastiffs between eight to ten weeks old and the second among puppy Mastiffs between six to fourteen months old. Good luck, and I commend you for taking action now while he is young and pliable. And be aware that some Neapolitan Mastiffs display predatory behavior toward cats and other animals that run. I would not risk keeping a Neapolitan Mastiff with another dog of the same sex. Most English Mastiffs are polite with everyone, but there is timidity (even extreme shyness) in some lines, and aggression in others.. To ensure a stable temperament, English Mastiffs need earlier and more frequent socialization than many other breeds. Potential animal aggression. If they can manage to get close enough to pet her shes fine, but she jets as soon as they look away. Typically she hides from them. A Mastiff should not be aggressive toward people! Slick561 New Member. Aggression is both a learned and an inherited trait. A behavior specialist with experience with guarding breeds, whom by instinct tend to be wary of strangers, is in order. She was the runt, the last to go and is extremely shy and nervous. Mastiffs are inherently predisposed to having a higher level of “suspicion” then other dog breeds making them suitable for guard work. I try to walk her every day but she lags behind me and ties to turn around because she wants to go home. A giant dog that bites is a liability. Typically, aggressive behavior is a “learned response” and/or results from a lack of proper socialization during the dog's developmental stages. Often described as gentle giants, English Mastiffs weigh in at around 220 pounds or more and stand between 28 and 36 inches tall. Mastiff suddenly aggressive. Are Mastiffs Aggressive? Though the English Mastiff temperament makes the breed extremely gentle and loving with family members, the massive size of these dogs makes them best for a more experienced dog owner. I have had my 4 month old mastiff pup since she was 8 weeks old, Both her parents were friendly. Socialization is critical in shaping dogs’ behavior especially during these two “fear periods”. She is afraid of passing cars, bouncing balls, approaching people, just about everything. If you are breeding Mastiffs to be ferocious guard dogs -- you are making a huge mistake!