Our local, state and national parks are precious resources accommodating many living things, dogs included. But man's best friend can also become nature's enemy if taken off a leash and allowed to run free.

A dog on the loose can be a nuisance and even dangerous. It's time for owners to take more responsibility and keep their animals tethered and safe.

"My dog is nice, he'd never hurt a flea" is one excuse that the park rangers often hear. But dogs off their leashes have been known to disrupt small animal habitats, attack other species such as ducks, and even confront rattlesnakes, which have been known to strike back with deadly consequences.

If left to run free on the open trail, a dog could become trapped or injured. A dog on the run also can be exposed to ticks, poison oak and other plants that have thorns and burrs.

The reasons to keep your dog on a leash are many. Who, for example, wants to assume the liability if his rambunctious pet attacks and hurts another person? Some people, particularly children, are afraid of dogs-even friendly ones. Please be respectful.

Just because we live in an area with bountiful open spaces doesn't mean we can ignore the rules of the road. Dogs are allowed on National Park Service and Santa Monica Mountains Conservancy trails, but not on the backcountry trails of the California State Parks, including Topanga, Malibu Creek, Leo Carrillo and Point Mugu. Leashes, even retractable ones, must be six feet in length or less, and keep the leash around Fido's neck. It does no good to take it off and leave it around yours.

Every dog owner enjoys watching his pet run free and there are several dog parks in the area that are perfect for that purpose. Rule of thumb: if you're not at a dog park, put your pet on a leash and keep it under control.

It's the law.