Tacoma’s Point Defiance Zoo & Aquarium is opening its gates to canines for its Dog Days event on March 6. From 9 a.m.-3:30 p.m., dog owners who are over the age of 18 can bring their dog to wander various paved paths with stops at the aquarium and habitats for insects, walruses, polar bears, muskoxen, and more. In order to participate, all dogs must be well-behaved, up to date on vaccinations, kept on a nonretractable leash no longer than 6 feet, and registered in advance with a $20 online ticket. Dogs are limited to one owner…