Dogs throughout Latin America carry the Chagas parasite — and boost the risk of people catching it. And it's not just shelter dogs, like these in Mexico, who are at risk. Even family dogs get the deadly disease. Jose Luis Gonzalez /Reuters/Landov hide caption

itoggle caption Jose Luis Gonzalez /Reuters/Landov

In June, the 167th Patrol Dog Class graduated from their canine narcotics and electronic media detection training, held by the Connecticut State Police Canine Unit. At far left is Thoreau, who now helps police in Rhode Island find computer hard drives. Daniel Owen/Courtesy of The Hartford Courant hide caption

itoggle caption Daniel Owen/Courtesy of The Hartford Courant

A fish that knows the way to go: the Chinook salmon, which appears to use the Earth's magnetic field to navigate ocean waters and rivers. Jeff T. Green/Getty Images hide caption

itoggle caption Jeff T. Green/Getty Images

The sexually transmitted cancer is common in street dogs around the world. Noel Celis/AFP/Getty Images hide caption

itoggle caption Noel Celis/AFP/Getty Images