HOA's and Invisible Dogs

I have a lovely golden retriever named Jack.  Our neighbors directly across across the street from us have two labs, Dax and Sadie.  Next door to them my mother-in-law has a lab named Blu.  So we have four large dogs in a three house radius.  Blu has received a number of complaints from the neighbors for leaving his droppings on the yard (and I mean multiple complaints).  Today Dax and Sadie's owner approached me stating that they had received a letter from the HOA insisting that anywhere that their dogs urinate, including on their own yard, must be replaced with fresh grass.  Their owner approached me this morning to ask if I too had received a letter, which I informed him I have not.  So Jack continues to skate by unnoticed all though is clearly the most flamboyant of the dogs, for further proof see the attached photo.