I have been using a plan I think maybe on the information section of new rider (not forum), when you worm spring, summer , autumn and winter... Now if they havent been wormed, if your quick I would probably get some normal wormer down and some stuff for tapeworm (they are supposed to be got Sept/Oct time I think, and then again in the spring wormer)... I used the Equimax I think its called - but you need one that covers roundworms etc as well as tapeworms, or use a couple to get them all covered. The winter will just be for roundworms, and then this autumn one again in the spring... Pramox do a year box I think, about £50 get a roundworm and tapeworm down them now (About £13 for Equimax online), and get a year box for next year