I've never heard of the National Park Service having canine units, but the U.S. Forest Service on the Angeles National Forest had a unit or two some years back. With the severe cutbacks the Forest Service has had, I'm not sure if they still have one now. They no longer show the law enforcement units on the Angeles CAD. I just looked up the San Bernardino National Forest CAD and they do show one "King" unit. The Cleveland National Forest might have one also, but their CAD rarely shows unit status at all. With all the illegal immigration activity on that Forest, it would seem like a good candidate for one.