Cocoa mulch: still toxic to dogs

In recent years, cocoa mulch began appearing as a bagged product in garden centers. The mulch consists of the shells of cacao beans, a byproduct of the chocolate industry. The product has been valued for its environmental aura, and for its pleasant, chocolaty scent (which unfortunately is lost with time and watering). It should come as no surprise that the shells contain theobromine, the active alkaloid in chocolate. What is a bit surprising is that the percentage of theobromine in cocoa mulch varies over a range overlapping with medium to heavy-duty chocolate products: up to 85 milligrams of theobromine per ounce of mulch, compared to theobromine content of 58 milligrams for milk chocolate and 138 milligrams for semi-sweet. Unlike the scent, the theobromine content of cocoa mulch does not diminish over time.

As most dog owners know by now, theobromine is toxic to dogs. Chocolate also contains caffeine, another compound toxic to dogs. Chocolate poisoning signs begin within several hours after ingestion and can include vomiting, diarrhea, hyperactivity, racing heart, high blood pressure, and ultimately coma. Death occurs most often from cardiac or respiratory failure.

Dr Tina Wismer of ASPCA says that if a 20 pound dog eats cocoa mulch, it takes only “0.16 to 2.6 ounces to cause vomiting, 0.33 to 5.2 ounces to cause high heart rates, 0.48 to 7.8 ounces to cause seizures”. The higher ends of the quantity ranges for each level of damage represent “dog-safe” cocoa mulch, which has had most of the toxic alkaloids removed—but is still toxic.

Cocoa mulch is relatively bulky and fibrous, so that it would take some commitment to eat a large quantity. However…you know how dogs are. They will eat anything, and of course they are attracted to the sweet smell of chocolate. Smaller, greedier dogs will be more at risk; the ASPCA has documented numerous poisonings and at least one canine death from cocoa mulch ingestion.

The “dog-safe” cocoa mulch may be a somewhat less toxic alternative for those determined to have (temporarily) cocoa-smelling garden beds. However, the canny gardener will note that cocoa mulch, whether quasi-safe or unsafe, is a spendy product and confers no benefits over the many cheaper, safer mulching alternatives available.

*Thanks to Tina Wismer, DVM, ASPCA Poison Control Center, for her insights.