Over the weekend the doting owner of two young lab mixes purchased Cocoa
Mulch to use in their garden. They loved the way it smelled and it was advertised to keep cats away from their garden. Their dog Calypso, decided that the mulch smelled good enough to eat and devoured a large helping. She vomited a few times which was typical when she eats something new but wasn't acting lethargic in any way. The next day, Mom woke up and took Calypso out for her morning walk. Half way through the walk, she had a seizure and died instantly.

Although the mulch had NO warnings printed on the label, upon further
investigation on the company's website, this product is HIGHLY toxic to
dogs.

Cocoa Mulch is manufactured by Hershey's, and they claim that "It is true
that studies have shown that 50% of the dogs that eat Cocoa Mulch can suffer
physical harm to a variety of degrees (depending on each individual dog).
However, 98% of all dogs won't eat it."

True information about the mulch can be found hereon snopes.com. This site gives the
following information:

Cocoa Mulch, which is sold by through a variety of stores, contains a lethal ingredient called "Theobromine". It is lethal to dogs and cats. It smells like chocolate and it really
attracts dogs. They will ingest this stuff and die. Several deaths already
occurred in the last 2-3 weeks. Just a word of caution, check what you
are using in your gardens and be aware of what your gardeners are using in
yo ur gardens.

Theobromine is the ingredient that is used to make all chocolate
especially dark or baker's chocolate which is toxic to dogs.

Cocoa bean shells contain potentially toxic quantities of theobromine, a
xanthine compound similar in effects to caffeine and theophylline. A dog
that ingested a lethal quantity of garden mulch made from cacao bean shells
developed severe convulsions and died 17 hours later. Analysis of the
stomach contents and the ingested cacao bean shells revealed the presence of
lethal amounts of theobromine.