You shouldn’t have your pet sleeping with you in your bed. It’s unsanitary. It seems like common sense but many people do it. Now there’s a study explaining the health risks.

Sleeping alongside your pets can make you sick.

It’s rare, but it happens. That’s why good hygiene means keeping Fluffy and Spot next to the bed, not on it, two experts in animal-human disease transmission say in a forthcoming paper.

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Chomel and co-author Ben Sun, chief veterinarian with the California Department of Public Health, did an extensive search of medical journals and turned up a hair-raising list of possible pathogens.

There’s plague (yes, bubonic plague, i.e. the Black Death); chagas disease, which can cause life-threatening heart and digestive system disorders; and cat-scratch disease, which can also come from being licked by infected cats.

Though many people love getting licked or planting a kiss on a pet, it may not be such a good idea, the authors say.

The researchers found several cases of various infections transmitted this way.

“The risk is rare, but when it occurs it can be very nasty, and especially in immuno-compromised people and the very young,” says Chomel, who specializes in zoonoses, the study of disease transmission between animals and humans.

Larry Kornegay, president of the American Veterinary Medical Association, called the article “pretty balanced.” These cases are “uncommon if not rare,” but even so, pet owners should use common sense to reduce risks.

Think about your health the next time your pet jumps into your bed.