Regular worming is a crucial aspect of caring for horses and ponies. Unless wormed regularly, some horses will develop serious health problems which could have lasting consequences. All owners should develop a worm control plan which best suits their animals and ensure it is routinely followed. If pasture is shared, then this will involve cooperation between different owners. If possible, seek advice from a local vet. Lots of local factors will influence the worming requirement, so a vet will be better able to advise on worming products and systems. Ideally submit a dung sample to a laboratory periodically to build up a picture of the internal condition of your horse. This can dramatically improve the effectiveness of your worming plan, and might well result in fewer worm treatments needing to be given.