Letting your dog take a dip in a lake or pond on a hot day is one of the joys of summer. A number of dogs, however, have died recently after becoming exposed to toxic algae, highlighting the deadly threat posed by microscopic bacteria lurking in these waters. In North Carolina, three dogs died earlier this month after swimming in a Wilmington pond and becoming exposed to toxic algae. Their owner posted on Facebook that the dogs “contracted blue-green algae poisoning” after their swim, and that the algae killed the pets within…