My older dog keeps getting random sticky substance all over him (top of head, chest, back, legs). It seems very random (meaning not always in the exact same place) and doesn’t seem to be coming from within. Is there some sort of weed or grass that he may be coming in contact with that could leave a sticky residue? I’ve Googled but not found anything. It’s like he got honey on his coat or something. Very strange. Could this be some sort of health issue that I’m overlooking? Or do you think it’s external??