On the Yahoo "Click to Calm" list recently, Jen asked "why do other [non-herding] breeds chase things?"
Prey drive was mentioned, dogs or wolves in the wild would have to chase prey in order to catch food. Through selective breeding, certain parts of the hunt sequence have been modified or truncated to suit the purpose of the breed. Liz Shaw gave these examples -
"Herders orient, eye, stalk and chase
Retrievers are good at the chase, grab-bite
Terriers have strong chase, grab-bite and kill-bite"
A herding dog who grabbed at stock excessively or killed stock would not be suitable for a farm. A retriever doesn't need to stalk prey that has been shot. Terriers were originally bred for hunting or pest control, and were required to kill.
These days, with some exceptions, our herders, retrievers, pointers, sight-hounds and terriers are not used for their original purposes. However, understanding their original purpose can give us some idea of how to use satisfaction of their prey drive as a powerful reinforcer and can go a long way to explain certain behaviors or tendencies within a breed.
The Yahoo "Click to Calm" list is for people training reactive dogs using the methods described in Emma Parson's excellent book of the same name. More information on Click to Calm can be found here. The Yahoo "Click to Calm" list can be found here.