There are many causes of over-excitement.
Your dog seeing prey-like bunnies, squirrels, birds can cause an excited response. Just being off-lead can excite for some dogs, listening to noises and sniffing the smells. Dogs rely on their senses for survival so with high sensory ability they can have little impulse control.
Impulse control is a learned behavior it needs to be controlled by the human from day one. A bit of time and consistency and expectation from the human is what is needed. Ask yourself this question, how do I want my dog to act around other dogs or people?
Do I want them to sit or to just look and walk by people and other dogs. Whatever it is can be accomplished by you making sure the wanted behavior at any given time occurs. Bad behaviors do not get any attention just correction.
The goal here is to prevent the dog from getting all worked up, meaning over-barking, jumping up on you or other people, racing around the house and jumping on counters. When a dog is in an over excited state they are not listening. As the Leader and teacher the process of correct and reward falls on our shoulders. Do you react to the situation by tightening up your body and pulling on the lead, this is just going trigger the unwanted behavior in your dog.
To change the dog’s behavior you as the human need to change you habits and reactions. The reason I say this is because your dog becomes tensor with each warning, each pull and each negative response from you they are learning to react. These responses from you train your dog to become over-excited and unruly. Change you’re process and the dog’s responses change.
One of the most common behaviours is created in the home with doorways. Over-excitement at the doorway encourages rushing and pushing past to see who’s there or worse making a bolt out of the door and jumping up, biting at heels, even growling and snapping.
It should be discouraged in a way your dog understands which is giving me space. All this over excitement is caused by the dog’s confusion as to what is wanted at the door. So again, ask what behavior it is you want exhibited at the door and train it.