Waste of money
I spent nearly $200 on this product for my four Shelties. No idea how it's working for worms, but can tell you it's completely ineffective on killing fleas. Found this out during a recent trip to the Outer Banks of North Carolina. Stayed in a rental home, which on the surface was very clean. Two days into our vacation my Sheltie Zoey started biting and scratching like mad. Fleas were crawling all over her. Had to buy a flea collar and bath her twice before returning home. Poor dog is rid of the fleas but her skin is still red and irritated. Will never use this product again.
SusanH231
Crofton, MD