My dog is aggressive. How to prevent fights when dog sitting?

I recommend that you keep them separate until you are sure they can get along when you are gone. Separating by a baby gate or keeping them on leashes would be fine. If they fight over toys, then all toys should be removed from the area. You also. Red to keep a close eye on them around feeding time. Here is a helpful article https://www.animalhumanesociety.org/behavior/how-introduce-dogs

You're right that there can sometimes be problems when introducing two dogs for the first time, especially if either of them has any history of aggression towards other dogs. I would recommend introducing them in a neutral place at first, like a park. Keep both dogs on leash, let them sniff each other briefly, then go for a walk together. This allows the dogs to get used to each other's presence without feeling pressured to interact. After the walk, take them both home and into the house together and if things are going well, let them off-leash to relax. If things don't go smoothly, it would be best to get help from a veterinary behaviorist (ideally) or a good reward-based trainer who can work with you in person. You can search for a behaviorist in your area here: www.dacvb.org or a qualified trainer here: www.ccpdt.org.

Hello and thanks for using PetCoach! I'm sorry to hear that Molly and your friends dog are getting into fights. Unfortunately it can be very difficult or even impossible to socialize them so that they will never fight. If they are both more dominant as you describe then allowing them to play together could result in a serious fight and injury. It is probably best to not allow them to play together in the future. If they must be together at times then they should both be leashed and wear basket muzzles to prevent injury. A dog can be easily trained to wear a comfortable basket muzzle by allowing them to put them self in a muzzle with treats. The handout here may help: http://info.drsophiayin.com/handouts-vol2-spring2011

Mealtimes are a common trigger for aggression between dogs in the same household - this may be a resource guarding issue related to the food itself, or could be redirected aggression that is happening when Harvey gets excited and/or frustrated while waiting for his food. The simplest solution would be to put both dogs in separate rooms with the door closed (or in their crates, if they are crate-trained) prior to getting their dinner ready. Feed them in their separate areas (again, in different rooms with the door closed if possible - separate parts of the same room isn't enough), then let them out once they have both finished eating. Pick up the bowls and put them away afterwards to avoid any resource guarding issues with the empty bowls. If this doesn't help, or if you are interested in a more detailed training plan to work on this behavior over time, I would recommend making an appointment with a veterinary behaviorist. He/she can evaluate both dogs in person to hep determine what is causing this problem, and put together a detailed plan for you to work on the problem. You can search for a board-certified veterinary behaviorist in your area here: www.dacvb.org

If Hondo gets into a fight every time he's at the dog park it would be best to discontinue going. For some dogs, the dog park is a high-stress place and it may not be for them. Other ways to exercise can include solo walks, fetch in secluded areas, and even focused activities that don't involve other dogs. If he's having trouble with the new puppy, or is severely dog aggressive/reactive it would be best to talk with a trainer or behaviorist in your area that can work with you on a plan to help get him more desensitized to other dogs, and potentially doing OK with some. In the mean time, if play gets too rough or one or both dogs seems agitated, taking a break and separating both dogs until they've calmed down is best. Make sure not to leave them unsupervised together as even the sweetest dog can accidentally injure another! Since aggression toward other dogs is a complex issue, it is best to work with a trainer who can supervise your techniques and plan in person.

The only way to stop this is to separate the dogs and not let them "play" together. Your aunt's dog is invading the territory of your dog, which your dog obviously does not appreciate. If your aunt's dog suffered bite wounds you may have to take him to a vet. This fighting is probably happening now because your aunt's dog had the "puppy advantage" when he was at your house the last time, but now he is starting to grow up and your dog will not give him the puppy advantage any more, so feels threatened in her rule of her territory. This is assuming your aunt's dog is the same age or younger than your dog.

Yes, some dogs can be very territorial and fighting can certainly cause damage. I would recommend that you are always close by to monitor their interactions and be available to separate them if needed. It is quite possible that as the puppy matures, it will find the boundaries set by your older dog and learn to respect them. However, some dogs never seem to get along. In this case you may have to confine them to separate areas of the house to keep them safe from each other. If the older dog is protective of toys or treats, you may just need to remove these all together to prevent fights. If it is during meal times, the dogs may need to be crated while eating or placed in different rooms. Here is some helpful information on fighting in dogs, including a section on training: http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=2303