Tag Archives: aggression


This will be a fairly lengthy post, as this is a complicated subject. Aggression in large-breed guardian dogs (in this case, especially focusing on Mastadors) can have several different causes or sources. We will attempt to delve into each one. How you deal with it relates to what the cause is, how long it’s been since it started, and how you’ve dealt with it up to this point (or just hoped it was a passing phase that would go away over time). Let me add that I am not an expert on dog training, but I rely on several professional trainers for advice and referral.

Overall Philosophy of Training

Mac, son of Lorna Doone & Charlemagne

People are fond of saying “dogs are people, too!” And refer to them as “fur babies” and “my kid”. But they are absolutely not. If you try to apply human or child psychology to dog training, you will fail miserably! Dogs do not react based on human emotions of love, anger, jealousy, etc. That’s why you can’t understand “why my dog is acting this way.” Your dog responds to things based on two aspects of his or her life: primal instinct and training, and how that causes him to react to any given stimuli. For instance, we call it “jealousy” when one dog comes up to you for attention, when you’re giving the attention to another. It is, technically, but it is not childlike jealousy. Canine jealousy is an instinct that attention from you is rewarding, and seeing another animal or person getting it, triggers the desire for the attention in his or her own primal interests. It’s actually quite different than a “feeling”, it’s a primal reaction or response. Some dogs respond to that “jealousy” more radically than others.

I know that folks hate this kind of direct assessment of dog behavior, but it is critical to understand when dealing with a serious behavioral issue like aggression. We have a funny saying here about this subject: “Don’t anthropomorphize your dogs. They HATE when you do that!” 

Onset of Aggression

Don’t put off dealing with this! The point at which the onset of the aggression happens will often steer you into the correct method of dealing with it. It is very important to assess this as quickly as you can after the very first signs. These would be growling or snapping at people or dogs that he or she already knows (including siblings), or with strangers; or showing that behavior on walks or at the dog park, when it was never a problem before. An aggressive dog can be scary when you have little ones in the house, and you start feeling that there is a possibility that it could get dangerous. 

To try to make this easily understood, I’m going to break this down into just two categories. The first is male dogs at the age of puberty (in Mastadors it is from 9-14 months of age, and aggression occurs in 20-25% of them). The second is male or female dogs at any other time in their lives.

Aggression in Female Dogs or Male Dogs Not Near Puberty

Female Mastadors or English Mastiffs rarely ever show signs of aggression. Males at any other time of life but around puberty, is also uncommon. When they start showing aggressive behavior, it usually has one of two causes, either environmental or medical.

Environmental: Have you just had any major change or upheaval in your life and circumstances? A new move can generate significant stress in a dog, and some don’t handle it as well as others. Having a stressful or chaotic home life can really jeopardize your dog’s feeling of safety and security, putting him or her in a “wary” state of mind, ready to jump into action at any perceived threat (whether you understand why it’s a perceived threat or not). I have seen aggression in a home that became a daycare, and had a half-dozen 2-4-year-olds creating a chaotic, high-stress environment their sweet dog just couldn’t handle. It’s happened with a couple whose marriage was disintegrating, and the toxic environment in the home deeply affected the dog to the point of aggression. A new environment without that stress level was the beginning of a new life for that dog. It wasn’t the owner’s fault, it’s just the way their dog handled that level of stress.

If you have a chaotic home life, it will affect your dog, because they are usually fairly sensitive creatures. The question is how they will deal with it. Some are easy-breezy and can just handle anything. Some will go off to a remote place in the room or house to escape it. Some will be very stressed, and that stress can build, waiting for a trigger.

Medical: A show of aggression can be the expression of persistent pain and discomfort, oftentimes not detectable by any other signs. If you cannot determine any other cause for the late onset of aggression, it would be wise to bring your dog to the vet, and have a blood panel done to see if there is anything obviously amiss. This kind of aggression is an easy fix, if the medical problem can be dealt with.

If your dog is not near puberty, is showing signs of aggression, and none of the above conditions apply to him or her, then the next step is to approach it the way I will describe below.

Aggression in Male Dogs Near Puberty

About 20-25% of male Mastadors will start to show aggressive behaviors at some point during or right after puberty. This is simply due to the genetic predispositions of the English Mastiff side of the family. English Mastiffs are a guardian breed, and they were bred for that job for centuries. There is no need to panic if this happens, but it also something you should NOT ignore, or think of as a “passing phase”. It rarely is. If you deal with it early and consistently, you can usually curb the behavior fairly easily. The longer you wait to deal with it, the more likely it is that you will need a professional trainer to get a handle on it.


I love positive reinforcement training as an option for nearly everything. Except aggression. Positive reinforcement training involves incentive and reward for good behavior. This is great for teaching commands, and controlling most behavior. It works well for general obedience, and for pesky stuff like jumping up on folks and for learning commands. It is probably superior in most areas of training.

Aggression though, is triggered by something in their genetic makeup and breed history. When it is triggered, commands are not heard or heeded many times, there is just a following of their primal instincts which have existed in their breed from the beginning. It is rare that positive reinforcement training can fix aggressive behavior. You generally have to provide a negative reward to get the desired results. I am aware that there are many professional trainers that are “positive only”, and criticize all training that involves negative stimulus. but they will nearly always tell you they may not be able to help with aggression. I use professionals that came from a background of training dogs for military and law enforcement, and who give guarantees concerning correcting aggression. The following are my suggestions to try chronologically, as they increase in intensity as you progress through the necessary steps.

Find The Method That Works

Starting with the least dramatic, these are the steps I recommend . You may luck out, and have the behavior disappear after the first level of attempt.

Muzzles are available as metal, nylon or leather and combinations.

Important: Safety First!  If your dog is already at a stage where he has growled or nipped at people in your own household, or friends that are frequent visitors, or on walks, it’s really important that you take danger out of the equation. Invest in a muzzle! I know, muzzles have a bad connotation to them. But they are an excellent tool to use, both in your training and whenever you can foresee a possible scenario that might trigger aggression, like a walk in the neighborhood or dog park, or folks coming over to visit. Get a proper-fitting one and use it!

There is a professional trainer that works with the outfit I mention below, who also owns one of my purebred English Mastiffs, Caesar. I have used Caesar as a stud for my Lab female. I will be posting an article from him soon (and linked here) all about the benefits and uses of a muzzle for training. It’s a great tool!

[Our trainer, Carl Griffith of Off Leash Canine Training, recommends e-collars by E-Collar Technologies.]

Spray Bottle: I keep an adjustable-tip spray bottle of water under the sink to this day, to deal with some of my girls growling at each other over food bowls when they’re in the house. Adjust the nozzle to a medium spray, not a stream, and not a mist. A good soaking spray. Spray directly in your pup’s face, accompanied by your verbal correction. If your dog doesn’t respond to this, or treats it like playtime, change from plain water to a solution of 2 parts water to 1 part distilled white vinegar. It is completely harmless, but will momentarily sting your dog’s eyes and get their attention.

Important: No touching during correction!

Your touch is always viewed by your dog as a positive thing, and therefore a reward. If you are trying to calm your dog down by touching him, petting or stroking while you talk to him, whether in a forceful or kind voice, your dog will view this as approval of his behavior! So each time you do that, you are actually rewarding your dog for his bad behavior, thus reinforcing it, rather than curbing it. You cannot hold your dog’s face and reason with him about his behavior, You have just done the opposite!


Training with an e-collar.

And electronic collar is the next step. This is not a “shock collar” which is what is used for electric fence systems, although they are sometimes erroneously referred to that way.  They have many levels to pick from, starting with just electronic tones, to a buzz or “nerve stimulation” (in adjustable levels). You may correct the problem without ever getting to the buzz level. I have had one of these collars on me, and jacked it all the way up. It was very uncomfortable. I would not call it “pain” but it reacted with my nervous system in a way that immediately got my attention without inflicting true pain or any kind of damage.

The internet is loaded with info and training videos for e-collars. It is extremely important to use these the right way. I personally have never used them, but you must use it correctly, or you could do more harm than good, as far as your attempts at training are concerned. Professional trainers that specialize in correcting aggression always use these. It will require patience and diligent consistency. Every episode with your dog needs to be responded to, and responded to in the same, consistent way.

Don’t be put off by internet pages showing grisly photos of injured dogs with burns. There is no way those injuries can ever happen with responsible use of these collars.  EVERY kind of training collar can cause damage by abuse. Use all the standard precautions, and there is no risk to your dog. For a really good, brief explanation of what these collars do, and how they work, check out this page.

Professional Training

If the spray bottle and educated use of the collar have not worked well enough, you will need to seek out professional training. You need to find someone who specializes in aggression, not just in behavioral training. The recommended route is to use their boarding/training program, which is usually two weeks long. I have recommended Off Leash K9 Training for many years, and watched several families get their loving dog back. These particular trainers have offices all over the country, having started here in Virginia years ago. They do guarantee their work, and will come back for extra training for both you and your dog, if the success is short-lived, and the behavior quickly returns.

Confidence training for an aggressive dog, in public.

The most important thing to understand about any training, but especially this specialized training, is that you MUST be consistent in doing the things, and using the commands that your trainer has taught you, consistently. It’s all about consistency! Once you get your dog home from professional training, and you are shown your dog’s new obedience and behavior, success or failure from that point on is almost entirely on you.
The most common reason for long-term failure of professional training comes from owners not applying everything the trainer taught them, and applying it daily and consistently.

It is a rare thing that an aggression problem cannot be straightened out. In 15 years of dog breeding, I have only seen professional training not work twice, once in a Lab, and once in a Mastador. Since I give lifetime support to all my puppy owners, I require that folks contact me before re-homing a dog, or whenever there is an issue I can advise on. I don’t ever want one of my dogs to end up surrendered to a pound or shelter. I will not re-home a dog that has bitten people, unless the adoptive person is fully knowledgable about the aggression AND has some experience dealing with it successfully.  In the case of both of these dogs, it was the vet recommendation to put them to sleep, and a neurological problem was thought to be the reason training did not work. In a case like that, it may well be the only option. 

Won’t neutering fix aggression in males?

This is a common misconception, though oft-repeated by some veterinarians. The answer is a simple “maybe”. My health guarantees are tied to a requirement that your dog not be spayed or neutered until they reach 24 months of age. This requirement is explained in another blog post. Puberty is too young to de-sex a dog, and given the possible side effects of early spay/neuter, is not worth the risk unless you’re in a last-ditch effort and the methods explained above are not working.

In my own experience doing one-on-one counseling folks dealing with aggression in a pup they got from me, of the ones that went ahead and neutered before 24 months, the aggression was curbed in less than half of those cases. I have approved neuter at 18 months (without sacrificing my genetic guarantees), as there is less than 10% of growth yet to come, and the danger is minimized at that age. Neutering is NOT a “silver bullet” for aggression. I don’t recommend it for puberty-age aggression, except as a truly last resort.

This maybe sounding to you that I have had “lots” of aggressive dogs come from my program. But considering that we produce an average of 100 puppies a year, and been doing that many for over a decade, it’s a fairly  small percentage. It is enough, however, for me to feel responsible to educate folks before they buy, and help them afterwards, should they run into any issues.

As I said, I am not an expert, and I welcome any comments, additions, or corrections from anybody more knowledgeable than I am, and will revise this post as appropriate. This is written to give owners of dogs that are showing aggression, a place to start.