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Canine Behavior/Large Dog Kills Small Dog


The dead dog
Pomeranian (Jinx) 5yrs Old Serious un-addressed medical issues.
On day of attack Jinx has a torn ligament in her knee and is described of barely being able to walk.
Owners state that Jinx has always had a fear of other Dogs.
Jinx lives at Home with a Cat Owner describes the Numerous Fights between these pets as the animals pretending to hate each other.

The killing dog.
Mastiff/Pointer cross 9 years old Neutered for 7 of those years. 140lbs  In perfect health as certified by a Vet the day after the attack. Mastiff walked daily through town and is described as being a quite friendly polite and lovable dog by other townsfolk.

The scenario:
On a public street in a town far from Jinx's home, where there is plenty of dog traffic. The owner of Jinx has the dog under a park bench that is part of a large flower planter. (No escaping out the back as the planter is there) Jinx is not on a leash. The mastiff walks down the street on leash and gets to beside the bench where Jinx  darts out barking and snapping at the Mastiff.
The mastiff takes one snap and Jinx is dead. There was no ripping chasing tearing rending or other action. It was just so fast. Jinx came out the big dog acted. All this faster than you can blink.

The mastiff cross is walked daily and has weekly pack walks. The mastiff is submissive and you can see it in the way he walks around with his head down  and actually looking sad all the time. I know this to be submissive behaviour. I am the owner of the mastiff. I am the alpa and there is no argument ever about that.

Anyhow question I have is my mastiff now a dangerous dog? Was it one before? It never bit any other dog in the past. In fairness though there was an attack on my dog by 2 french bulldogs also off leash. I saw those 2 coming and asserted myself and my mastiff got bit a couple times but he did not act out as like i said I am the alpha.

Does my mastiff now have a fear of other dogs? He never displayed anything like this in the past even after the duel attack. Things seemed normal. I actually took him right from that fight to his "weekend" pack and left him with them for a few days just in case he wanted to develop or harbour some ill wiil.

Or was this just a calamity of events that could only have one outcome?

My dog is now undergoing a 21 day behaviour assessment. So i am just asking what you think?
The owners of Jinx are not interested in anything they may have done wrong that brought this about. But i would like to know if there was or is something i can do in the future. not only for my dogs safety but also the safety of other dogs or people in the community.
Animal control asked me to voluntarily

Thank you for your question. What a horrible situation to find yourself facing. I'm sorry that you and your dog and the other family are having to go through this.

Your question ended mid-sentence so I'm not sure what it is that animal control asked you to voluntarily do...

But to address your description of events, I will start with some behavior observations you made. You said that your dog "walks around with his head down and actually looking sad all the time." I would not describe that as submissive. I would more likely describe it as insecure and possibly even timid or fearful. This is a potential issue because most bites are caused by fear. I am not a fan of working for a dog to be "calm/submissive" as this usually means insecure and unpredictable. I always work toward a calm/confident dog. A confident dog is easy going and takes things in stride, is not easily rattled and is rather diplomatic in social interactions. This is just a note for future - I would work on confidence building exercises rather than exercises to enforce submission.

As for your dog's past experience, he was attacked by two small, off leash dogs prior to the incident in question. This past history has likely sensitized him to the sudden approach of small dogs - he's been assaulted in the past by a particular "type" and is now a little more hypervigilant about that "type". If he were a human who was mugged by a 5'5" white person wearing a hoodie, he might get nervous whenever he sees a short-ish white guy in a hoodie because he has a history of bad encounters with that 'type'. So in your dog's case, "small dog" was the type that now makes him nervous.

The Pomeranian was not on leash, but since you describe that you and your dog walked right along side the bench, a leash wouldn't have made a difference in this case. They could have had him on a 6-foot or 10-foot leash and their dog would still have darted out all teeth and noise. That dog also had an ongoing fear of big dos, and also felt vulnerable due to poor physical health and pain. Although I might have not brought a dog in that condition to a public park, I also can't judge them for wanting to give their dog some off property time.

So, their dog who is fearful and in pain darts out defensively and startles your dog who is fearful of small dogs. Your dog reacts and a single contact likely broke the neck, killing the little dog. That particular encounter probably had no other outcome option.

Now, to your main question - is your dog 'now dangerous' or was he all along... The reality is that any living dog who has teeth is potentially dangerous. Your dog now has a known history of killing another dog. Whether it was in perceived self defense, simply a startle reflex with no intention of causing harm, or with outright intent to kill is actually irrelevant at this point. He reacted to the threat with a fatal bite which indicates minimal skill at bite inhibition. And it is possible for him to do this again.

Please know that I am not saying your dog is vicious or bad. I don't know your dog. I wasn't there. I have no way of knowing what your dog's intention was when he made contact with the little dog. I can only look at the outcome. As a responsible dog owner, your only two options are to either never take him off property again (which severely limits his quality of life and yours with him), or to teach him to love wearing a muzzle and then always, ALWAYS have him wearing a basket muzzle when he's off property, or will be around other dogs.

The reality is that this could have been a one-time, perfect storm situation that will never ever present again. But now that he has a history, we cannot ignore it. If he ever bites again and you did not take steps to prevent it, you will be liable, no matter what the circumstance is surrounding the situation.

So, I don't know what the 21 day behavior assessment consists of. In the US it's a quarantine meant to ensure the dog doesn't have rabies, but doesn't involve a behavior assessment. So I'm not sure what is involved in such a thing in Canada. I don't know if they're going to push his boundaries until he snaps again (every living thing has a breaking point and will snap if pressed far enough), or if they're just observing his "normal" behavior to see what he's like generally. You also didn't indicate if this is an at-home quarantine or if he's at a kennel somewhere.

Assuming that he passes his quarantine and is returned to you (or you're allowed to keep him), you absolutely MUST teach him to love wearing a basket muzzle and then have him wear it without fail every time he's in public for the duration of his life. A muzzle does not mean he cannot cause harm. He can still plow into someone/something and cause blunt force damage, but he cannot bite with the muzzle on and that's the goal.

Below is a link to my favorite muzzle and a link to a video to teach you how to teach him to love wearing it. Do not think of the muzzle as a punishment. Think of it as a safety net. If he's wearing the muzzle, both you and he can relax and enjoy your outings and others will be able to decide for themselves if they want to keep their distance. If he's not wearing it, you will always be wondering if a little dog is going to come running up and your dog will kill another one...

Baskerville Ultra muzzle

How to acclimate your dog to wearing a muzzle

Again, I'm sorry that you and your dog have to face this issue. But I commend your efforts to be responsible and take steps to avoid a similar event in the future.

Worcester, MA Behavior Specialist
Masters Candidate - Animals and Public Policy (Animal Behavior)
Tufts Cummings School of Veterinary Medicine

Canine Behavior

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Jody Epstein, CPDT- KA, APDT


IF YOU BELIEVE YOUR DOG IS ILL OR INJURED, PLEASE CONTACT YOUR LOCAL VETERINARIAN IMMEDIATELY. THIS IS NOT THE FORUM TO ADDRESS URGENT MEDICAL ISSUES. I AM NOT A LICENSED VET AND HAVE NO DIAGNOSTIC SKILLS. ***I have been answering questions on All Experts for over 5 years now. I enjoy being able to offer assistance in this forum. I do need to be clear, though. If you’re looking for free advice about a specific behavior question, you MUST submit your question to me via All Experts. If you bypass All Experts and write to me directly through my website, I will ask you to submit via All Experts. On the flip side, if you’re local to Los Angeles and you wish to speak to me privately about an in person consultation, please go through my website. I appreciate your assistance in keeping my volunteer work on the volunteer site.*** I can answer questions about the following canine behavior issues: obedience, timid/fearful & fear-based aggression, nuisance behaviors, families that are expanding with either new human or new animal members. If you have potty training questions please first read my trio of blogs at If you still have questions after reading the blogs you can post your specific questions here. PLEASE be as specific as possible when asking a question. Give me a detailed example of the situation - dog's behavior, body language, circumstances surrounding the issue, what the consequences are (another dog's response, your response), etc. I can only provide insight if I can get a picture of the whole scenario. If I ask for further details, please provide them. In person I would normally observe for at least 90 minutes to assess the situation and the dynamics before offering tools and suggestions to modify it. In writing it is ever so much more difficult. Thank you for your participation in the process.


I have been professionally modifying behavior and training obedience for 7 years. I have owned dogs my entire life. I have just changed the name of my business. It is no longer Good Dog! Dog Training. The new name is Nutz About Mutz!. If you see previous questions with the Good Dog! website information, that is my response.

I am a Certified Profession Dog Trainer - Knowledge Assessed (CPDT-KA), #2133301 ; I am a member in good standing with the Association of Professional Dog Trainers (APDT), #77763 ; I am an AKC certified Canine Good Citizen evaluator (CGC), #71253

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I have a graduate education in animal behavior and learning. (While I completed my coursework and did the requisite research, I did not defend a dissertation. I am qualified, but not certified and so technically not a doctor. This is commonly referred to as Ph.D.-ABD which means All But Dissertation.) My educational focus was with non-human primates, but my personal interest is with domestic dogs and their relationships with humans and other animals. I continue to educate myself to canine-specific behavior through extensive reading, online interactive workshops, vidoes and attending canine behavior conferences.

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