There’s some ruff news for those who enjoy cuddling cute puppies.

If you’re shopping around for one at pet stores this holiday season, take extra caution, the Centers for Disease Control and Prevention has warned, since the furballs have been linked to a bacterial outbreak across the U.S.

Puppies have been tied to 30 cases across 13 states of people being infected with Campylobacter jejuni — a bacteria that’s the most common cause of food poisoning — the CDC said in an outbreak advisory this week. There have been four resulting hospitalizations, but no reported deaths.

“Epidemiologic and laboratory evidence indicate that contact with puppies, especially those at pet stores, is the likely source of this outbreak,” the CDC stated.

Even if they appear healthy, pets may carry the bacteria that can make people sick, the CDC said. But infected animals will typically appear tired or sluggish, won’t eat and have diarrhea.

In humans, the bacteria can cause diarrhea, fever and abdominal cramps, and may also cause nausea and vomiting, the CDC said. Symptoms typically appear within two to give days after exposure and last for around a week. While most cases will clear on their own without antibiotics, in some cases, people may require medication or hospitalization.

The CDC advises that those choosing a pet to bring home select one who is “alert” and “playful,” and if a puppy appears to get sick after being brought home, that they should be taken to a vet.

Additionally, the CDC urged people to practice good hygiene when coming in contact with animals, including washing hands thoroughly after handing and cleaning up after them.