How Often Are Animals Struck by Lightning?

Animals sometimes huddle together during storms, making them easy targets as lightning spreads. Roman Mikhailiuk/Shutterstock

In an eerie apocalyptic scene reminiscent of a horror movie, 323 reindeer were found dead in a national park in Norway. Officials believe the herd was likely huddled together during a severe thunderstorm and the animals were killed by lightning, National Geographic reports.

It's not the first time a large group of animals has been killed by lightning. Just days after the reindeer died in late August, 19 cows were killed in East Texas while taking shelter under a tree during a storm. Lightning struck the tree and the cows just fell, according to the Fort Worth Star-Telegram. In 2005, 68 cows died after a lightning strike in New South Wales, Australia, as National Geographic points out. And a few years later, lightning struck wire fencing in Montevideo, Uruguay, killing 52 of the cattle inside. During a 1990 thunderstorm, 30 cows were killed on a farm in Virginia.

As a human, your chance of being struck by lightning each year is about one in 1 million in the U.S., according to the National Weather Service. Odds of being struck in your lifetime are about one in 12,000. We have no idea what the odds are for animals because cases are not well-documented, but Brent McRoberts of Texas A&M; University says lightning accounts for 80 percent of all accidental livestock deaths.

"Unless there is a barn nearby, livestock are out in the open during thunderstorms, so their chances of being hit are greater," he says.

"And the types of injuries are about the same. One study shows that while about 70 percent of humans struck by lightning still survive, the fatality rate of horses and cattle is much higher. This is because no one is around to treat the injured animal, plus the body mass of the animal is larger than a human, meaning more tissue damage can occur. Often, a rancher will see a dead animal on his property and not see any apparent cause. A necropsy (animal autopsy) often reveals that the animal died from a lightning strike."

reindeer killed by lightning in Norway
More than 300 reindeer, including 70 calves, seem to have fallen over where they stood during a recent storm in Norway. Håvard Kjøntvedt/Norwegian Nature Inspectorate

How lightning kills

We always think of lighting as a bolt that comes down from the sky. But direct lightning strikes that hit and kill someone (or an animal) are rare, meteorologist Ron Holle of the National Lightning Detection Network tells the Washington Post.

However, a stroke of lightning can contain 20,000 or more amperes of current. And when that hits the earth, that electricity spreads out in the ground and can be potentially deadly. For a person standing on the ground affected by the current, it can travel up one leg, through your body and down the other leg. Along the way, it can potentially stop your heart or arrest your breathing. These ground currents can be particularly deadly for animals because the current passes through the animal's entire body between the front and rear legs. The greater the space between where the current enters the body and where it leaves the body, the greater the potential for serious damage.

There's also a type of lightning called "side flash" or "side splash," where lightning jumps from an object to a living thing or jumps from living thing to living thing.

As the Post explains:

Side splash occurs because lightning follows the path with the least resistance to electrical current to the ground. If you’re standing within a foot or two of a tree hit by lightning, the lightning is likely to jump from the tree to you because to a lighting stroke, you are a nothing but a bag of salty water with much less electrical resistance than a tree.

So one lightning strike to a tree or a strike to the ground can jump back and forth among all the animals nearby.

"Lightning can strike tall trees and spread to the animals sheltered beneath the branches," Dean Scoggins, DVM, equine extension veterinarian at the University of Illinois, tells The Horse. "Once there, the lightning bolt may bounce between animals, including several in the group. Also, lightning frequently goes down the tree, and if it's a shallow-rooted tree, it will travel out through the roots so the ground will be involved as well."

Keeping animals safe

Like people, animals are safest if they can get indoors to a well-grounded location. Avoid higher elevations, like hilltop pastures, metal (fences, gates, barns, feeders) and single trees, which attract lightning more than a group of trees.

It's not always possible to corral farm animals if a storm kicks up quickly, but if you're outside with your dog or another animal and a storm hits, the National Weather Service suggests these additional tips to stay safe:

  • Find shelter in an enclosed, grounded building.
  • Avoid open fields, the tops of hills or any high ground.
  • Stay away from tall, isolated trees or any tall objects. If you're in the woods, stay near a lower stand of trees.
  • If you're in a group, spread out to avoid the current traveling between you.
  • Stay away from water and wet items, and all metal objects. Water and metal don't attract lighting, but they are excellent conductors of electricity.