We use Heartgard Combo (covers heart worm and all the other worms) packs for my boys. There is cheaper out there but my boys have always been on heartgard so we decided to keep using it. (When you have 6 dogs weighing from 50 to 75kg it does get expensive). I did think about switching to Proheart which is cheaper but after reading bad reports about the product I decided to stick to the one we know our dog's don't have a problem with.
As far as ticks and fleas - we wash our dogs weekly in the hydrobath with Fido's Itch Free Rinse. When fleas/ticks are really bad in an area where the dogs are working then we may use frontline (but not used regularly). Our boys rarely have fleas but ticks are something they tend to pick up in the work environment.
