An e-mail circulating through cyberspace warns pet owners not to use cocoa mulch because it can cause serious health problems--or even death--in dogs. But is the message true? Or is it an Internet hoax?

ConsumerAffairs.com, which received a copy of the e-mail, learned pet owners should heed this warning. That's because cocoa mulch contains a compound called theobromine. This naturally occurring compound--found in many plants, including cocoa beans--can be harmful to dogs.

"Cocoa bean shell mulch can result in adverse reactions in dogs," said Dr. Steven Hansen, veterinary toxicologist and senior vice-president of The American Society for the Prevention of Cruelty to Animal's (ASPCA) Midwest Office. That office houses the ASPCA's Animal Poison Control Center.

Dr. Hansen said many dogs are attracted to the smell of cocoa mulch.

"Some dogs will eat large amounts of fresh mulch, which can lead to intestinal upset and if the amount is high enough increased heart rates and trembling," he told ConsumerAffairs.com.

But he added: "Death is very unlikely with current products as the residual theobromine is very low."

A few years ago, the ASPCA investigated several cases in which dogs ingested cocoa mulch. The organization studied those cases in response to the growing number of reports about dogs eating that type of mulch.

The ASPCA's study revealed:

• Vomiting was reported in 50 percent of the cases;

• Tremors were reported in 33 percent of the cases. In these cases, the amount of cocoa mulch ingested by the dogs was described as "large or significant;"

• Tachycardia (rapid heart rate), hyperactivity, or diarrhea were reported in 17 percent of the cases;

• High amounts of cocoa mulch can cause tachycardia, muscle tremors, seizures, and even death. One dog died after eating a large amount of cocoa bean shell mulch that contained 0.46% theobromine;

• There were no clinical signs of illness in 33 percent of the cases;

• 67 percent of the cases came from dogs in California.

"Pet owners should avoid (the) use of cocoa bean mulch in landscaping around dogs with indiscriminate eating habits," the ASPCA said when it released its Cocoa Mulch Report.

Some companies that make cocoa mulch warn pet owners about using the product around dogs.

The maker of Blommer's Cocoa Shell Mulch, for example, has a warning on that package that states: "Note: contains trace amounts of theobromine, a compound that dogs can be allergic to, so use caution when using around dogs."

But not all cocoa mulch products carry that warning, according to the latest e-mail about this problem.

That e-mail describes how a dog named Calypso ate a large amount of cocoa mulch--because it smelled so goodand then became gravely ill.

"She vomited a few times which was typical when she eats something new, but wasn't acting lethargic in any way," the e-mail states. "The next day, Mom woke up and took Calypso out for her morning walk. Half way through the walk, Calypso had a seizure and died instantly."

The e-mail adds: "Although the mulch had no warnings printed on the label, upon further investigation on the company's Web site, this product is highly toxic to dogs and cats. We are passing this on not to scare you but to make you aware of a commonly purchased item that may have a potentially fatal effect on your pets."

The e-mail is signed: "Your Family at Deepwood Veterinary Clinic."

ConsumerAffairs.com tried to contact that clinic, but it did not respond to our inquiry.

Veterinarians, however, aren't the only ones warning pet owners about products that contain theobromine.

The Hershey's company--the largest maker of chocolate and sugar candies in North America--also cautions pet owners about that compound.

"Dogs metabolize theobromine very slowly," the company states on its Web site. "As a result, theobromine can have a serious effect on the animal's heart, kidneys and central nervous system. It carries the same risk as does a dog's consumption of other common household items such as coffee, tea, cola beverages and certain houseplants."

Meanwhile, experts say other types of mulch--including cedar chips and straw--are less toxic than cocoa mulch. But some may contain oil and resins that can cause gastrointestinal problems in their pets.

Consumers who suspect their pets have eaten these or other toxic products should contact their veterinarians or the ASPCA's Animal Poison Control Center at 888-426-4435.