mate i had the same thing years ago,a neighbour,thats all the info i was told,reported that my two dogs were chained up in the garden with no shelter so the rspca made a visit,now are the days id just f**k them off out of it but being naive at the time i showed them in,the two dogs were kept in a complete purpose built kennel,the guy laughed it off even to the point of saying they probably being taken care of better than they would be in the rspca kennels,you will not find out who reported you but likely to be a disgruntled neighbour for what ever reason,f**k them and enjoy your dogs mate