The Riverside Police Department in suburban Chicago, Illinois is warning residents to look out for "zombie raccoons" stumbling through the area, the Chicago Tribune reports. The raccoons get their spooky nickname from a disease that causes them to walk upright, stagger aimlessly, and bare their teeth [PDF]. Despite resembling furry members of the undead, the scariest thing about them is their potential to spread a deadly disease to dogs. Distemper is a virus that infects certain mammals like raccoons, foxes, coyotes, and skunks. Domesticated dogs are also susceptible to the disease. When a dog has distemper, it discharges watery pus from its eyes, starts coughing, develops a fever, loses its appetite, and becomes lethargic. The virus attacks the respiratory, gastrointestinal, and nervous systems, and complications such as seizures and pneumonia can lead to death in dogs. Distemper can easily spread from wildlife to dogs through the air. That means living near a diseased raccoon is enough to expose a dog to the virus. Fortunately, there is a vaccine for distemper, and if you've taken your dog to the vet for routine care it's likely already protected. Most dogs receive their distemper vaccine at the same time as their parvovirus, canine adenovirus, and rabies shots. Dogs who haven't been vaccinated and older dogs with weakened immune systems are at the greatest risk of contracting distemper. As long as the distemper outbreak persists among the raccoon population in Riverside in Chicago, local police recommend that pet owners keep a close eye on their dogs. Pets should always be supervised when outside to keep them from interacting with wildlife. And when taking them to places with other dogs, like pet daycare centers, it's safest to choose businesses that require all canine guests to be vaccinated. Regardless of whether or not they own pets, Riverside residents can help pet owners in their neighborhood by looking out for sick raccoons. If they spot a raccoon displaying zombie-like behavior, they can alert the police to have it removed. [h/t Chicago Tribune]