This isn't an isolated incident. According to a study conducted by Stephen Herrero and Hank Hristienko, both leading authorities on bear behavior, dogs were involved in more than half of all black bear attacks between 2010 and 2013. The study didn't mention grizzlies. Bears aren't the only issue for dogs in the backcountry. Moose have also injured hikers while out on the trail with their dogs. Here and here are two relatively recent incidents in Colorado alone.
I don't understand why Shenandoah National Park continues to allow dogs in the backcountry. I believe it is the only national park to do so. This incident highlights why pets do not belong in areas with abundant wildlife, particularly where there are predators. The Great Smoky Mountains has prohibited dogs in the backcountry since its establishment in the 1930s. The park website explains this policy with these reasons:
• Dogs can carry disease into the park's wildlife populations.If you look at other park websites they also cite similar reasons. If these are legitimate factors in the Smokies, and nearly every other national park, why aren't they factors in Shenandoah National Park? Or in all of our national forests for that matter? U.S. Secretary of the Interior Sally Jewell should implement a consistent policy that protects wildlife, visitors and pets across all backcountry areas managed by the agency.
• Dogs can chase and threaten wildlife, scaring birds and other animals away from nesting, feeding, and resting sites. The scent left behind by a dog can signal the presence of a predator, disrupting or altering the behavior of park wildlife. Small animals may hide in their burrow the entire day after smelling a dog and may not venture out to feed.
• Dogs bark and disturb the quiet of the wilderness. Unfamiliar sights, sounds, and smells can disturb even the calmest, friendliest, and best-trained dog, causing them to behave unpredictably or bark excessively.
• Pets may become prey for larger predators such as coyotes and bears. In addition, if your dog disturbs and enrages a bear, it may lead the angry bear directly to you. Dogs can also encounter insects that bite and transmit disease and plants that are poisonous or full of painful thorns and burrs.
• Many people, especially children, are frightened by dogs, even small ones. Uncontrolled dogs can present a danger to other visitors.