Using a dip to apply flystrike treatments is generally not advisable, whether for prevention or treatment of strike.
Cyromazine—the only flystrike chemical registered for use in dips—is suited to prevention rather than treatment of strikes.
However, preventative treatments are best applied when there is a high flystrike risk—that's usually on longer wool.
Since sheep have been bred to resist rain penetrating the fleece, the dip fluid, likewise, does not penetrate the fleece sufficiently to provide good protection. These types of treatments are not formulated to provide good effect from a surface application (like pour-on or spray-on treatments) and are best applied by jetting into the fleece.
The advantages and disadvantages of shower, plunge and cage dipping are provided in the table below.
Notes on best practice shower dipping.
Notes on best practice plunge dipping.