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Canine Behavior/Boxer agression


Hi, In Feb. we brought two male Boxer/Shepard mix puppies to our home.  Very attached to each other, snuggle most of the time with each other etc.  They are currently 9 months old and still get along well, but we have had two incidents where they have very aggressively attacked each other to the point we could hardly separate them.  Both incidents occurred outside our house in our yard (they have only had typical puppies wrestling in our home).  The first incident over what appeared to be a dog toy that was left in our yard by another neighbor.  The second time we are unsure what sparked the aggression.  Afterward, they seem "concerned" over the other and whine if kept apart.  We don't want to even think about having to re-home either or both, but are concerned as we have children.  Ideas?  Note: both dogs have been neutered.

Thank you for your question. What you're describing sounds like resource guarding behavior. This is when one dog has decided that some thing (toy, bowl, food, bone, person, space, doorway, leaf, etc) is a valuable treasure and is concerned that another individual may try to steal it. So, due to this fear of losing their prized treasure, they guard it from anyone they think may be trying to take it. They will direct this guarding behavior toward another dog, a person, another animal - anything they think might be 'making a play' for their treasure.

So, the first incident you describe was a toy found in the yard that had been tossed their by a neighbor. That makes the toy new, exciting and very valuable. Perhaps one dog thought "this is mine!" or perhaps both dogs had that thought. If just one dog was guarding, the other may have been curious and gotten too close or may have just been walking by when they were essentially ambushed by the guarding dog - in both these scenarios, the other dog is suddenly forced to defend himself.

If they both thought "this is mine!" then a it could lead to a full blown fight as they both try to guard and take/keep possession of the toy.

In all likelihood, this is also what happened the second time, though you may not have noticed what was being guarded.

We definitely want to address this before it escalates further. There are some basic management to put in place to start.

1. Supervise all toy time. Give them toys to play with, but when play time is over, put the toys away out of sight and out of accessibility to they have nothing to guard. If this is only an issue outside, then have a bin with a lid and put the toys in there as you head back inside.

2. The children are NEVER alone with the dogs. Not even for a second to answer the phone or the door or put something in the microwave or to go pee. If the room will be empty of adults, then either the children go with the adults or the dogs go with the adults. But children and these dogs are NEVER alone together.

Please understand - I'm not trying to be alarmist here. I have the same rule for all dogs, even if we trust them implicitly. The reality is that we can't trust the children, and the dogs have a right to defend themselves. Children tend to invade the personal space of dogs, stare at dogs, try to take toys from dogs, lay too close or on the dog's bed, etc. So, when there is no human there to make sure the children respect the dog and the dog's space, then there should be a barrier between the kids and the dogs. Period. In this situation, because there is a resource guarding issue developing for at least one of the dogs, it's possible to generalize to guarding against a human as well and children have delicate skin. As mentioned above, dogs can guard anything they feel is valuable. They may guard one of your kids from the other dog or they may decide they're guarding a doorway or their bed, or whatever. In any of these cases, whether that guarding is directed at each other (dog-to-dog) or at a human, the kids could get hurt.  So... always supervise when the kids and the dogs are together.

3. There are things we can do to help the dogs feel better about being near each other when something "valuable" is around. This is best done with the assistance of a professional who can observe the dogs in person, help determine what the triggers are and create a protocol that's tailored to your dogs and your home. Essentially, it's a counter conditioning and desensitization protocol to help the dogs better tolerate each other in that circumstance (desensitization) and change their emotional response from one of "I must guard this from you" to one of "Oh cool! you're here! It's better when you're here!! (counter conditioning). The process should be tailored to your dogs and your home. And it's a bit more involved than a simple walk-through here as you need to make sure your starting distance is sufficient, that the timing of rewards is solid and that the timing of moving closer together (and how much closer) is accurate.

I saw that you're in Wisconsin. One of my favorite people in this industry, Sarah Kalnajs, is a world renowned author/DVD of canine behavior and speaker. She's a Certified Dog Behavior Consultant in the Madison area. I believe she's in Israel right now lecturing, but will be home soon. You could contact her about setting up a consultation.

If you're not convenient to Madison, I expect Sarah will be able to point you toward someone local to you who uses positive reinforcement techniques, who has an understanding of canine behavior, body language and can help you create a protocol that will help these two boys be comfortable when outside with each other, even if they find a cool toy.

Nothing is 100% and there may still be something that is just too valuable to one of them, but with patience and consistence and a positive approach, you can teach them that even when valuables are present, great things happen when they're near each other, AND nobody loses their prized possessions.

You can also search on the APDT website for a trainer local to you. Just be sure that they do not utilize aversive techniques such as electronic/shock/vibration collars, physical force (kicking, poking, so-called 'alpha' rolls), spraying or startling the dogs. You want to work with someone who is setting the dogs up for success, rather than setting them up for corrections.

Some reading that you may find helpful:

Mine! A Practical Guide to Resource Guarding in Dogs by Jean Donaldson. This is a good book to help you better understand the motivation behind resource guarding and how to deal with it when it's directed toward humans. It is adaptable to dog-dog guarding behavior, but you have to keep both dog's comfort and stress level in mind and you have to adjust how you're setting it up, using leashes, barriers and usually one person per dog, in order to make it work - which is why it's useful to have a session or two with a local professional who can teach you how to work through the issue with your dogs.

<Fight! A Practical Guide to the Treatment of Dog-Dog Aggression</b>, Jean Donaldson. This walks you through various reasons why dogs fight and how to work through those issues. There is a chapter on resource guarding.

The only thing I would change is her recommendation for breaking up a dog fight. If loud noise just above their head doesn't work, rather than grabbing the base of the tail (especially for dogs who have little or no tail), I would hook the dogs at their hip (top of the thigh), lift and wheelbarrow them away from each other.

Hopefully some of this will prove useful to you. Please feel free to followup if I can be of further assistance. If you do happen to contact Sarah, please let her know that I referred you.

Los Angeles Behaviorist  

Canine Behavior

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Jody Epstein, MS, CPDT-KA


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 8 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 and many other issues. 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 a professional obedience trainer for 9 years, and specializing in behavior modification for 8 years. I have owned dogs my entire life. I own my own dog training and behavior modification business called Nutz About Mutz.

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

Publications ; ; Multiple articles in the local pet magazine Pet Press (found across Southern California)

I have a masters degree (MS) in Animals and Public Policy, with a minor in Animal Behavior, from Tufts Cummings School of Veterinary Medicine. I also have 3 years of graduate education in Animal Behavior and Learning from UM-Missoula and UL-Lafayette. I continue to educate myself to canine-specific behavior through extensive reading, online interactive workshops, vidoes and attending canine behavior conferences, workshops and seminars. Beginning in March, 2017, I will be the Behavior & Training Manager at Second Chance Center for Animals in Flagstaff, AZ.

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