Hirst's sheep gets an armed guard

If you thought Damien Hirst's pickled animals had lost the power to shock, think again.The embalmed sheep that created a sensation and swept the Young British Artist to superstardom is at the centre of a mounting controversy in Los Angeles, after being given its own armed guard.

Visitors to the Broad Contemporary Art Museum, the city's new $120m (£61m) gallery, which opened in February, have expressed disquiet at the presence of three gun-carrying security officers, one of whom now stands a few feet in front of Hirst's 1994 Away From the Flock.

The guard has been criticised for interfering with the viewing experience of the sheep-in-formaldehyde and preventing visitors feeling welcome to linger over the exhibit.

Formaldehyde, a carcinogen, is toxic and the museum is increasingly concerned that vandals may attempt to smash the tank in which the sheep is housed and create an environmental disaster. The Broad was evacuated for an hour in April after Hirst's sheep sprang a leak.

Across the globe, vandalism has become a problem for galleries housing modern art.

In recent years, visitors have urinated on a Marcel Duchamp urinal at the Tate Modern in London, vomited on Mondrian's Composition in Black, Red and White in New York, and frolicked in Tracey Emin's My Bed.

Hirst's sheep has been a target in the past. In 1994, when Away From the Flock was first displayed at the Serpentine in London, the artist Mark Bridger poured black ink into the tank, relabelling it "black sheep".