A lurcher is "traditionally" a sighthound (grey, whippet, saluki, afghan(!), borzoi (!) etc etc crossed with a working or pastoral dog (collie, Alsation, Beddy,) etc etc. and a long dog is Lurcher to Lurcher mating or sight hound to sight hound, ie Saluki/Grey or so I was brought up to believe. Cheers, D.