Cocoa bean shell mulch is an attractive mulch that people are increasingly using for landscaping around their houses. It looks good, smells great, but can pose a problem for dogs who can’t resist its smell or taste.

Cocoa bean shell mulch is a by-product of the chocolate industry and so contains some of the chemicals found in chocolate. These chemicals, called methylxanthines, include caffeine and theobromine. They are part of the reason why people like chocolate, but they can make dogs sick. A research study by the American Society for the Prevention of Cruelty to Animals poison control center has confirmed what veterinarians have been suspecting, that dogs will ingest the cocoa bean shell mulch and it can cause illness.

Dogs with methylxanthine toxicosis may show vomiting, muscle tremors, elevated heart rate, hyperactivity and diarrhea. Some dogs appear to find the mulch attractive and preferentially ingest it.

“The ASPCA advises pet owners that they should avoid using this mulch around unsupervised dogs, and dogs with indiscriminate eating habits,” said Dr. Steven Hansen, senior vice president of the poison control center.