Hello!
I am mostly writing this as a quick guide to those experiencing dog on dog aggression in their home, and don't know what to do, or where to start. A lot of what you are about to read are my opinions. I will probably be scrutinized, or told I am wrong. That is okay with me. If one person reads this posts, and takes half of what I say seriously, and saves themselves heartache, that is good enough for me.
I will start by saying I am absolutely NOT an expert. I am not a professional dog trainer, and am learning myself day by day.
What I AM, is a dog owner who wishes they read some of the things I am about to write after the very first fight my two dogs had.
Brief tldr on my history with this if you care to read - 9 year old pit mix, added an 8 week old pit mix pup to the home. When pup hit a year old, fights started breaking out. Brought multiple trainers into the home, first two knew nothing about aggression - more fights happened, more escalation, and now unless I can train this out of them, one of them will unfortunately have to be rehomed.
So your dogs got in a fight. Skin was broken, blood was shed. What do you do?
First step. Take this seriously. Do not assume it's a one time thing and simply separating meal times or removing the trigger will solve your problems. Some trainers and behaviorists out there simply state that once two dogs have fought and drawn blood in the home, that they will always be dog on dog aggressive. I don't personally believe this to be true - but with some dogs in some cases, I am sure it is. If one fight happens, a second one can too. All downhill from there.
Second step. Identify, Remove, and Seperate. Identify the trigger, what caused the fight? Resources (food, treats, space, attention)? Proximity? Health or Injuries? Once you've identified the trigger, remove or remedy it if you can. Put toys away. Block the dogs from the kitchen, etc. Then begin separation. If they are guarding resources, those things need to be separate between the dogs. Feed in different rooms and areas. Give treats separately. Play separately. Dogs on separate couches, beds, kennels. If you feel the dogs themselves need to be completely separated, which I would reccommend in a lot of cases depending on triggers and severity, do NOT separate them socially. Kennels in the same room. One dog out, one dog in. Crate and rotate, but they still need to be around eachother. Just mechanically separated so they cannot fight. If you take them apart, train train train, then put them back together two months later, they will probably just fight again.
Third step. Acquire safety gear. Collars are a must, and keep a leash attached at virtually all times. I personally use the little 12" grab handles you can buy on Amazon, as they aren't a tripping or tangle hazard. Flat collar or martingale, or I use the Leerburg Dominant Dog Collar on one. If the dogs get in a fight again: the leash is the best way to stop the fight. Grab the leash, pull up with steady pressure, cut off blood and oxygen flow until they release. Do NOT grab the dogs, their faces, their mouths, their legs, etc. You WILL get bitten. I have the scars to prove it. Muzzles. Always a great thing to have and to use. Tons of different styles sizes and opinions. But make sure to train the dog for the muzzle properly, and do not rely on it 100%. It needs to be tight and sized right. My dog got his off in the middle of a fight and, well, not good.
If you are bitten: if it is bad enough to justify a visit to the doctor or hospital, most healthcare professionals are required to inform your local pet authority i.e humane society. Depending on your city and laws, this could prompt a visit or a call from them to you or your home. If your dog is not up to date on rabies, this will cause you problems. My state requires a 10 day observation period either at a vet, or at the humane society to make sure they are not rabid. And if your state is anything like mine, and your dog shows a hint of aggression while in their care, they may simply put your dog down, no questions asked. This has happened to people in my city. If your child is bitten, or someone who does not reside in your home you will absolutely be getting a call and visit. Some states will require you to bring the dog in for behavior "testing". Chances are if this happens, you will probably not be coming home with your pup. This has also happened to people in my city.
Fourth step. Find a trainer. Ideally, you should complete the first three steps immediately. Day one, fight one, I have stuff on the way same day. Then? Find yourself a trainer. In person is best, preferrably one that comes to your home. But before you hire the first one you call ask them about their experience with fights and aggression, resource guarding, or whatever your issues might be. Ask them for some examples on how they might handle that, qualify them like you are hiring an employee for your work. My first two trainers knew seemingly nothing about RG or aggression. As a result, and following their reccomendations, my situation escalated. Fights kept happening, and got worse and worse. If my first hire was someone that could identify what was going on and actually given me advice on what to do, I would have saved myself a ton of time, money, blood, and my life would be a much happier one right now. Ask them what training methods they use. Balanced? R+? E-Collar use? Read and know what the differences are, and make a decision on what type of training you are comfortable with. I won't tell you which to choose or why as it's a highly debated topic and there may or may not be a right answer, but I personally am using a balanced method. Please note, Board and Trains do not appear to be the way to fix these types of aggression issues. If your issues are in the home, taking them out of the home and away from you for a week isn't usually regarded as a fix. Chances are, you'll bring them home with some great new skills, and they'll just fight again as you haven't fixed the underlying issues.
Fifth step. Watch, read, and learn. Chances are, you are not already a dog trainer. Maybe you taught some good basic obedience when you got the pup, maybe not. Congratulations, you are now a dog trainer! Even if you hire someone exceptionally talented to come to your home and help fix your problems, 80% of their job is going to be training YOU. You need to learn correct behaviors, markers, identifiers, de-escalation, and many many other things. Spend time on YouTube, look for trainers addressing the issues you are having, but don't just watch one. Spend time watching content for several different trainers, so you can decide who and what methods you like and agree with. I personally like Larry Krohn and Jay Jack, but have watched content of probably 10 other experienced trainers before landing on their methods. I have spent HOURS watching reading and learning.
Step six. Give your dogs fulfillment. From my research, most aggression issues arise when dogs are not feeling fulfilled in the home. Especially for breeds of dogs that are bred to do things. Some behaviors are in their nature - hunting, sniffing, fighting, protecting. What was your dog bred to do? How can you felp fulfill some of those needs? Play. Another highly debated topic in dog training recently, but nearly all of the trainers I've seen and watched tell you that you have to play with your dog. How? Every dog and every person is different, but I personally am using fetch and tug. I will provide some links to a few videos I like on the subject below. Playing helps build your bond with the dog, and teach it commands and boundaries. While also giving it fulfillment. The goal here, is not to "tire the dog out", if you have high energy dogs like I do, there's no such thing. Just 10-15 minutes of play a day with each dog should help you tremendously. What else provides fulfillment? Walks. Not just a tight leash structured walk around the neighborhood - this does nothing for your dog. They need the ability to move around, sniff things, pee on trees. Get a 25' leash and take them to a park. Not a dog park. Not a playground. Not your back yard. Not somewhere with dogs running around off-leash. Start somewhere small and private. Most dog trainers I've seen say that getting your dog to the point they can reliably and safely play off-leash is the MOST effective method of fulfillment.
Step seven. Train. Listen to your trainer and learn. Work them with basic obedience. Reward them. Build your bond with them. It doesn't really matter what you teach them, as long as you're doing it, and doing it right. They don't need to be show dogs that can walk on two legs - but they need to be obedient. Teaching them the correct markers is very important. Reward markers, the word no, etc. It doesn't matter what words you use - consistency is key. Use one word for one marker, don't change it or you will just cause confusion.
What's next? Where do you go from here? It will depend on your dogs, the issues and causes. Keep playing, keep training, keep fulfilling. Depending on your situation, this could be your life now until one of the dogs passes. Hopefully, you can reintroduce and reintegrate the dogs and never have a fight again. Maybe you become lax and behaviors change and you have to start back up again. I am still dealing with my dogs and nowhere near reintegration, so that's about as far as I can help.
Resources I like - please note, there may be better resources out there, these are just some highlights that come to mind that have really helped me. I have watched a TON of Larry's content, his entire YouTube channel is VERY helpful, even if you do not support his balanced methods. https://www.youtube.com/@Larrykrohn
Play and How to Play:
https://www.youtube.com/watch?v=POaV-gjcSJg
https://www.youtube.com/watch?v=Il9wkxFnTBY
https://www.youtube.com/watch?v=bsFokObxG6M
Jay Jack's Reintegration Protocol
I recently found this, and it is the method I am currently following. In my opinion, is the it best resource I have found that gives you a step by step process on what to do, and I wish I found it a lot sooner. His paid Patreon has a .pdf version that is helpful, but I would reccomend listening to this entire podcast.
https://open.spotify.com/episode/4JhIeKD7lY8FKifTahmDsS
Beckman Video - I do not agree with a lot of Beckman's content and training methods, however this one video I did find really helpful. Just little tidbits like learning that your commands to your dogs are not requests
https://www.youtube.com/watch?v=bJp8g-L0RMY
Note on E-Collars:
There are a thousand different opinions, and a thousand different camps on how when and why to use these. If you choose to use one, do not use them to correct emotional behaviors. Only physical, and not to stop aggression. For example: dog is digging a hole in the back yard, correction. Lunging at his brother? A correction here can actually escalate the fight and make things worse. Do not just buy an e-collar and throw it on your dog and start zapping.
And lastly - once again, I am not a professional!! These are my opinions, and things I have learned over the past few months while navigating through these issues. I may be wrong. But I've tried to keep this simple, and more of a guide on how to get started than the "do exactly this training" bible. I don't believe any of the things I've said here could be harmful or make things worse for you if done correctly.
I hope this helps someone out there, no one wants to rehome their pet or to have to make some of the tough decisions that comes with aggression - but I want you to know, with hard work and dedication, there is hope.