Maureen Fitzpatrick is a graduate of The Academy for Dog Trainers and owns Seven Cedars Dog Training on beautiful Whidbey Island, Washington.
Leash reactivity is when leashed dogs bark, lunge, or aggress at other dogs. In her book Fight! A Practical Guide to the Treatment of Dog-Dog Aggression, Jean Donaldson paints a masterful picture of how this often develops, starting with perfectly normal healthy pups:
A puppy is removed from his litter and, because of disease risk, is quarantined away from other dogs until he has been sufficiently vaccinated, which, depending on the vet, may be at around age 3, 4, or 5 months. The owner then starts walking the dog on the street and encountering the occasional dog on leash. The dog’s intense excitement, sudden non-responsiveness to the owner and pulling on leash make the owner feel out of control. The concerned owner starts avoiding other dogs, choking up on the leash, jerking the leash or otherwise attempting to discipline the dog, all selectively in the presence of other dogs.
The dog’s motivation is increased – partly through deprivation and partly through leash frustration: being rarely able to approach and investigate the other dogs he sees. When he does make contact, his excitement and inexperience cause him to commit social gaffes – he is too much in the other dog’s face and fails to read the other dog’s body language. Occasional scuffles result. The owner is now more alarmed and escalates the avoidance of dogs, mechanical control procedures as well as the warnings and punishments around other dogs.
The motivation is still off the charts, the skills no better, the dog older and bigger and another element is now added: a growing association of other dogs with frustration, punishment and a tense owner. This grim picture may be further worsened in the dogs he encounters do not have fantastic social skills either.
This spiral continues until [the dog] is frankly aggressive to other dogs, often even in other contexts, such as off leash. There are variations on this history and varying degrees of severity, but the combination of limited experience, hyper-motivation, few or no off-leash opportunities, barrier frustration and conditioned association of other dogs with punishment and owner tension are usually present to some degree.
How to Prevent Leash Reactivity
Give your puppy lots of safe, supervised, off-leash play opportunities with other puppies as soon as they have had their first DHPP and initial dewormer. Continue to allow these opportunities throughout their puppyhood. My bias is that this is the most important bit!
Continue to socialize your dog with other off-leash dogs throughout their adult life. Occasionally, in spite of all of our best efforts, genetics has something to say about the matter and we end up with a dog who can’t go to the dog park. In that case make the effort to curate a play group for your dog (perhaps all female friends for the adult male who can’t abide other male dogs, or all large dogs for your prey driven sight hound). Keep your dog socially tuned up. Consult a positive reinforcement trainer with an interest in dog-dog socialization if you need help.
If your dog is able to go to the dog park, by all means enjoy! You can also consider a reputable day care once a week.
When meeting on leash
Select dogs you know, or at least non-reactive dogs to meet
Keep slack in the leash
Keep meetings brief – watch the dogs. Don’t get lost in a human conversation such that early signs of tension are missed. Say hello, allow 20-30 seconds of sniffing and then move along with a food lure and some happy talk.
Consider parallel walks with dog friends rather than face to face leash greetings. If you’d like to socialize your dog on-leash this is a much better choice.
Don't mix off-leash and on-leash dogs. Remember the on-leash dog is "trapped" by the leash. It's not fair to expect them to keep their cool when they are at such a disadvantage.
Associate the sight of other dogs on leash with happy talk and treats as opposed to leash tension and stern reprimands.