as my dog has been scratching and bitng herself and we,ve tried to discover what,s causing it someone has said it may be mites all i know is she,s worse when she,s been out for a run So if it is mites how do i get rid?

If you're thinking Sarcoptic mites (which can live without a host for a few hours so no need for your dog to come into contact with an infected animal) then Stronghold from your vet's would clear it up :)