You may be able to file a personal injury lawsuit against the dog owner for your son's injuries. Depending on where your son's accident happened, the non-bite dog attack law of that state will apply.
PA Non-Bite Dog Attack Law
In Pennsylvania, dog owners need to keep their dogs under proper and adequate control. This is also known as PA's "leash law." Dogs do not necessarily need to be leashed per se, but they need to be:
If the dog that lunged at your son escaped from his yard due to a broken gate, then the dog was not confined to the owner's properly. If it was not the first time that the dog escaped from his home/yard due to the broken gate, then the owner may be responsible because he/she knew that the dog can escape. The owner should have fixed the broken gate to prevent the dog from escaping.
See related PA dog attack legal article: What You Need To Know If You Were Attacked And Injured By An Unleashed Dog In Pennsylvania
NJ Non-Bite Attack Law
In New Jersey, dog owners may be held strictly liable for injuries caused by their dogs in dog attacks and non-bite attacks.
If the dog was being walked by his owner and the dog lunged at your son which caused him to fall and hurt himself, the owner may be held strictly liable if the owner knew of the dog's playful propensity to jump and lunge at people.
The dog does not have to show a dangerous propensity for the dog owner to be liable. For non-bite dog attacks, if the dog has a playful or mischievous propensity and hurts someone without biting as a result, the dog owner will be strictly liable for the victim's injuries. Therefore, the dog owner may be liable for your son's injuries.
In order to determine which state law applies, we would need to discuss the details of your son's accident. As you can see, I need to know all of the facts and details surrounding your son's accident in order to properly assess his case.
Feel free to give me a call to schedule a FREE consultation. 877.944.8396. You can also get more information about dog bite/attack cases in a book I wrote on serious and catastrophic dog attack cases. The book provides information you need to know before you decide to hire a lawyer. Click here to order a FREE copy of the book. The Pennsylvania and New Jersey Dog Bite Book.