Generally, gundog handlers use the whistle for three main commands:
The ‘Stop’ command – normally a single tone of varying lengths
The ‘Turn’ command – normally two or three pips
The ‘Recall’ command – normally a quick series of pips, depending on whether you are handling a close hunting spaniel or a far-ranging pointer.
As already mentioned, the most common whistle used is the plastic type. It comes in three different pitches, and this can help your dog in situations where there are a lot of handlers and dogs all being commanded by the same kind of whistle. The plastic whistle is a pretty universal whistle being used by most breed handlers.