Why does my dog get aggressive when other dogs are on leash?

Leash aggression is actually pretty common. When an animal feels threatened or scared they need fight or flight. When they are on leash you have now removed the option of flight so you are way more likely to have a fight reaction and this is why you are noticing this on leash vs. off leash. This is something that needs assistance of a professional trainer, working under the dogs threshold to address the issue. You can see varying amounts of improvement depending on the severity of the case but it's going to take a lot of work and commitment on your part. Please seek help from a qualified professional. Not addressing this issue now will only make it worse and harder to deal with later.

Leash aggression is a complex behavior issue that is best handled by a professional who can give you some hands-on guidance. I would recommend making an appointment with a veterinary behaviorist (www.dacvb.org) or a good reward-based trainer who has experience working with aggression issues in dogs (www.ccpdt.org) The general approach to treatment for this problem is to reward the dog for calm behavior in the presence of his triggers (people, other dogs, etc.), starting at a distance where the dog is able to be successful, then gradually moving closer as long as things are going well. For some dogs, this means that you may need a lot of distance at first! Having a professional to work with is very helpful, since they can help you set up controlled training sessions with "helper" dogs or people to practice until you and your dog have the hang of things. Punishment of any kind for this behavior (including verbal corrections, leash corrections, shock collar, etc.) is not recommended because it often makes the problem worse over time. Steer clear of any trainer who recommends these techniques, and look for an educated reward-based trainer instead.

I'm sorry to hear that your dog is having this problem! Behavior issues like this are quite complex, and often very difficult to handle successfully on your own if you don't have any training experience. And particularly with an aggression problem, it may not be safe to attempt to work on this without professional assistance. If at all possible, I would strongly recommend making an appointment with a veterinary behaviorist who can evaluate your dog in person and help you put together a detailed plan to work on the problem. Although the initial visit may be somewhat expensive, in many cases owners are able to stay in contact with the behaviorist via phone or email about how things are going without the need for repeated in-person sessions - which cuts down tremendously on the long-term cost vs. working with a trainer every week. The behaviorist may also recommend medication or other adjunct treatment options that could be helpful in addition to the training plan. You can search for a board-certified veterinary behaviorist here: www.dacvb.org If your dog is mainly aggressive to other dogs when she sees them on-leash (the most common form of this problem, in my experience), I would also suggest the short book "Feisty Fido" by PhD behaviorist Patricia McConnell - it has very sound, useful advice for dealing with this issue that may help to get you started.

This is a case for a professional trainer. I suggest you work with a professional trainer or join a dog club where you can do obedience training with your dog and work on the aggression issues. You can also have your dog evaluated by a veterinary behaviorist who can help you with behavioral modification tips as well as medication if necessary. Here is where you can find a veterinary behavioral specialist: https://www.dacvb.org/search/custom.asp?id=4709

It sounds like your pups may be a little under socialized and may need some extra help. Tugging on a extra short leash can just create more tension and stress which may encourage the barking and aggressive behavior. It is best to contact a local trainer or behaviorist in your area who can work with you on dog on dog aggression, usually with a training technique of BAT or desensitization to get your dogs used to being around and positively interacting with other dogs. It is important to work with someone in person that can be there to step in if there is a problem and observe/teach what behaviors are happening. If your dogs are able to, a basic obedience class may also be useful to teach some loose-leash walking manners, and help you and your dogs understand and work better together.

Your question is cut off, but if Igor is showing aggression toward other animals, I highly recommend talking to and working with a trainer or behaviorist near you. Usually, training related to nerves/aggression around other animals is worked on with Behavioral Adjustment Training (BAT) or other desensitization techniques to keep your dog from reacting negatively toward other animals (or the object that is causing the trigger.) While this site is mostly US-centric, there are listings for behaviorists world-wide that may be able to help. http://www.dacvb.org/about/member-directory/

Sounds like she is becoming overprotective of you. You really need to stop this behavior ASAP. It is best if you work with a a professional, in-home dog trainer. I like the company Bark Busters. I suggest you contact them for a consult. ( https://www.barkbusters.com/dog-training-queens )