Drives in dogs are survival-related needs. Dogs can encounter many different situations. If a situation or condition requires a dog to take action to increase the likelihood of its survival or the survival of its species in general, it has a need for action.
We consider this need for action a negative state of tension that the dog can only satisfy by taking the needed action. The need proceeds the action. For this reason, the need is often said to motivate or drive the action. Because of this motivational characteristic of needs, they are regarded as producing primary drives in dogs. This is not unique to dogs. It applies to all animals.
Example: A Squirrel Runs Up a Tree
A dog sees a squirrel move. The movement of a small animal is the situation.
Catching and eating prey is a survival requirement. So chasing, catching, and killing it is the needed survival action.
The behavior triggers, regardless of whether the dog is hungry or not; that is irrelevant. Dogs genetically enjoy all survival-relevant activities by themselves. Until the dog starts chasing it, it will be in a negative state of tension. Only engaging in chasing will relieve the negative tension. This particular behavior is part of what is considered prey drive. There are other drives.
Drive Theory
Drive theory is based on the principle that organisms are born with certain psychological needs and that a negative state of tension is created when these needs are not satisfied. When a need is satisfied, the drive is reduced, and the organism returns to a relaxed state. – Clark Hull, Principles of Behavior, 1943)
For more on dogs, read our articles The Dog: A Brief History and Dogs: The Canine Model. You can also read the book Principles of Behavior (PDF) by Clark Hull, 1943.