Calm and Cool on Both Ends of the Leash
If your dog is still a puppy, it's best to work on leash politeness right away. Puppy training classes present the opportunity to socialize your puppy with other dogs and with people (both on- and off-leash depending on class set up). A consistent schedule of sessions in doggie daycare is a great option for exercise and socialization, too! A puppy who is used to interactions, who knows that encounters with other dogs and people are simply normal, will be less likely to be overly excited, anxious, or aggressive when those encounters happen on a neighborhood stroll.
But what if you've adopted an adult dog with leash behavior issues? Or what if you're just noticing these troubles as your pet ages? Having a dog who growls, snaps, and lunges at other pets or at people during what should be a peaceful potty outing can be frustrating and scary.
First, we would recommend avoiding situations that could trigger this unwanted behavior until you are able to bring your dog in for a veterinary behavioral consultation.
Plans and results will vary depending on your dog's triggers, overall health, and other factors. Often it is anxiety or even fear at the root of the angry-looking pulling, barking, and snapping. Your dog could simply be unsure of how to behave in some animal and human social situations; he or she may feel afraid or defensive because of this uncertainty. The resulting anxiety manifests as pent up tension, and this is what can turn into aggression. Therefore, it is likely that your vet will recommend reinforcing basic commands in the calm and comfort of home, away from whatever ignites anxiety and aggression. In this "safety zone," work with your pet to develop quick communication and response to the "sit," "stay," and "come along" (or "heel") commands. Through positive reinforcement, help your dog become fully attentive to these commands so that he or she offers you an immediate and appropriate response. Your veterinarian and/or dog trainer can help you identify the best techniques for you. And in the meantime, schedule your walks for "slow times" in your neighborhood, and leverage your fenced-in back yard (if you have one) for play time and exercise.
Know that dogs sense our anxiety. If you spot a dog down the block and start worrying that your dog will try to "go after" it, you might tighten your grip on the leash and your breathing may become quick and shallow. This tension travels down the leash, and your dog will develop an even stronger association between that given situation and stress.
When your veterinarian and/or dog trainer gives you the green light, you might begin to introduce the trigger situations with some distance. Start with a short walk, staying close to home just in case, and give yourself the chance to cross the street or cut a wide arc into an off-path field if you encounter one of your dog's triggers. Ask for a "sit/stay," and offer a reward for the correct behavior. High value training treats double as distraction and positive reinforcement. With time and success, work on gradually decreasing the distance from other pets and people. The goal is desensitization; if your dog is focused on you (whether for a treat or, later on, for social and directional cues), he or she can let the triggers pass by until they just aren't triggers anymore.
Dog training for any issue--basic obedience, agility, or behavioral trouble--takes time. You'll want to check back with your veterinary and training team frequently for medical progress exams (yes, behavior issues are medical issues!) so that you can advance or adjust as needed. Don't be afraid to backtrack if you and your dog need to! It's better to be safe and go back a step or two than to try to introduce too much too soon and risk a fight or injury. Be patient and flexible, and make sure that you have a strong veterinary and training team in your corner. And, of course, be proud of yourself and your dog for your successes; shared victory is great for the pet-human bond!