Humans love chocolate. In fact, some people love it so much they have it in their landscapes--as mulch, that is. Over the past few years, the use of cocoa-bean mulches has become more popular. They not only prevents weeds, they also looks attractive and smell wonderful. However, dogs are also attracted to this sweet, chocolatey smell, and that can be dangerous for your pooch.

Research has shown that this mulch may be ingested as dogs dig through it. Of course, this may not be an issue if your dog is well behaved and understands that gardens are to be appreciated from a distance. My dog, however, loves to be directly involved with any gardening activity. She also loves to dig and will put just about anything in her mouth. My guess is that she is more the rule than the exception. So what happens when dogs ingest cocoa mulch?

Chocolate contains two compounds that are toxic to dogs. They are methylxanthines, specifically theobromine and caffeine, and each has an LD50 of 100 to 200 mg/kg. The LD50 is the quantity of a chemical calculated to be lethal to 50 percent of the organisms in a specific test situation. It is expressed in weight of the chemical (milligrams) per unit of body weight (kilograms). However, severe and life-threatening clinical signs may be seen well below this dose. Seizures can occur at 60 mg/kg, and mild signs such as vomiting, diarrhea, bloating, and restlessness can occur at only 20 mg/kg (ASPCA/APCC Database: Unpublished data).

So how much is too much for a pooch? The amount of methylxanthines in cocoa hulls is substantial at 255 mg/oz. And that's just the theobromine; no data was available for caffeine. In comparison, milk chocolate has only 64 mg/oz of methylxanthines, and less than 1 oz of milk chocolate/lb (2 oz/kg) is potentially lethal to dogs. So 65 oz (4 lb) of milk chocolate would be potentially lethal for my 65-lb dog. But, if she were to eat cocoa-hull mulch, by my calculations, it would only take about 2.25 oz to produce mild signs and 12 oz to be potentially lethal. Of course, these amounts would be much less for a smaller dog. Some manufacturers do include a warning statement on the bag. So, if you have dogs or wandering neighborhood dogs, another type of mulch should be considered.

For more information, call your local veterinarian or animal poison control center. You can reach a link to the center by clicking on http://www.aspca.org. Also at this site is an article on chocolate intoxication (http://www.aspca.org/site/DocServer/toxbrief_0201.pdf?docID=111) that gives detailed information on clinical signs and treatment, as well as an example for calculating the methylxanthine dosage. At the above Web address, you'll also find information on protecting your pet from pesticides and fertilizers, as well as a list of plants that are toxic to pets.