CHICAGO (CBS) — If you see raccoons in the forest preserves – or in your neighborhood – acting like zombies, your dog’s health might already be in jeopardy.

WBBM’s Steve Miller explains.

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It’s the middle of the day. You notice a raccoon in your back yard. You might notice how sleepy it looks.

“What you are most impressed with is these animals walking extremely slowly, and not seeming to care about their surroundings,” said Dr. Donna Alexander, administrator for Cook County Animal & Rabies Control.

Alexander said such zombie-like appearance in raccoons could mean canine distemper.

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“They are not showing any fear of humans. They are walking around during the daytime. Sometimes they lie down, even though they are completely awake,” she said.

Right now, county officials are finding a significant number of dead raccoons with the virus; even more than 12 years ago, the last time there was a distemper epidemic in pet dogs in Cook County.

Dr. Alexander said raccoons are everywhere these days, including right in the heart of Chicago, and leave traces of the virus, which your dog can pick up.

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She said the key is to vaccinate your dogs for canine distemper.