Throw rollers for a while. Small dogs can take a bit longer to develop the spacial coordination required to catch flyers and even floaters. You can get small-sized frisbees which are even regulation in IDDHA (not sure about the other competitive orgs and series). These are better than soft frisbees, which can teach some bad habits and also make your dogs unwilling to play with anything else. Not to mention the fact that floppies fly like rocks.
Get a Hyperflite and you will never want to toss anything else - here's a source for pupper size Hyperflites: http://www.mightymitedoggear.com/discs.html
Becca Shouse
Maggie and Zhi (queen bees), Ben, Gus, Cord, Rocky, Ted (BCs), Lu and Tully (Maremma flock guardians)
Irena Farm, Semora, NC
