DOWNTOWN LOS ANGELES - At the corner of Towne and Seventh streets in Skid Row, Officer Scott Brown sits tall in the saddle atop one of the horses from the Los Angeles Police Department's mounted unit.

His horse clops up onto the sidewalk and promptly relieves itself, a load of manure falling to the middle of the walking path. As Brown and another officer on horseback trot away, a middle-aged man strolling toward them expresses his disapproval with a raised voice and waves angrily at what the horse left in its wake.

It is a situation Skid Row denizens say is common. Neighborhood activists claim that the police do not clean up after their animals, even when their waste hits the sidewalk, which in this area is more than a pedestrian path: It's where hundreds of homeless people lay their heads at night.

"Basically, they're [defecating] on peoples' homes," said Jeff Page, Skid Row's representative on the Downtown Los Angeles Neighborhood...