Dogs are ideal hosts -- to worms and other parasites, that is. Animals that sniff, slurp, lick, and gobble anything in their paths, including dirt, trash, and poop, are bound to pick up pests.

A recent study of 288 dog parks in 30 cities around the U.S. found that 85% of the parks were contaminated with canine intestinal parasites. Of the 3,006 dogs that visited these parks and were ...