The dogs, loaded onto a Dodge cargo van marked “Mississippi Mutts On the Move,” like at least tens of thousands of others making the trip northward might once have died for lack of shelter space. Before the Oktibbeha County Humane Society shelter started shipping puppies and dogs north a decade ago, half the dogs and cats in its care were put down — a “kill rate” of 50 percent. Last year, when the humane society transported 3,000 dogs north, 93 percent of its animals left the shelter alive.“We are the epitome of the Southern shelter. We are too small for the amount of animals coming in,” said Michele Anderson, a humane society board member. The shelter was built in 2005 to hold 100 dogs and cats, but typically has 120, using crates in hallways to hold the excess. Every day brings in as many as 20 more animals.The trend of relocating animals began in the mid-2000s, when a slew of massive hurricanes devastated the South and left thousands of pets homeless. Shelter dogs, many lost or abandoned by fleeing residents, were moved around the country by volunteers hoping to eventually reunite them with owners. Animal rescuers took note, set up a travel network and since then, thousands of Southern animals have made treks north.