In fact, the only pack animal in North America prior to Columbus was the dog, and some native villages had as many dogs as people.
Dogs were used to guard and alert villages and camps, as well as for pulling travois, and as a food source by at least some tribes. Native dogs were distinguishable from wolves by their curved tails.
Today, "Rez dogs" are a staple in Indian territory out west.
These animals are not always feral, but many are maintained in a way very different from the way dogs are kept in the East or even in nearby towns.
Vehicle impact, injury and death due to severe winter elements and disease are treated philosophically, as if the dogs were part of the landscape, the same as deer.
Few dogs are spayed or neutered and not too many are vaccinated.
Dog pack predation on deer, cats, sheep, goats, and even horses is fairly common. People too get atacked.
It's easy to paint too broadly. There are many reservations and many cultures. But when the land is without bound, and the people are poor, dogs rarely do well except in the area of reproduction. That's as true in Macon, Georgia as it is on the Rosebud Reservation of South Dakota.
Hat tip to "Prairie Mary" Scriver for this video on rez dogs, and their people, on the Blackfeet Reservation in Montana.
Rez Dogs from Sancho Ex on Vimeo.