Baby oil! My paddock has several huge pine trees that the horses LOVE to rub on :( For years I would be devastated when they got sap on them because I knew that it would be a long time before that spot eventually fell out and new hair grew. The oil works best on new sap spots that haven't dried yet, but even some older ones are salvagable. Just saturate the area with the oil and let it sit. You can do this several times until it comes out-- works best in the hot weather for some reason. It also won't damage the coat. Good luck!