Intelligent Worming

We have just had the whole yard tested for worms.  We sent a small sample of droppings from each horse to our vet.  The results have shown that most of the horses have no worms but two have a high 'count' (0-150 is acceptable, our two are over 1000!).  So now instead of worming the whole yard using expensive chemicals (it is thought that some worms are becoming resistant to the wormers due to over use) we only have to worm two.  We will test the whole yard again in three months.  Seems 'intelligent' to me!