Chocolate Toxicity
By Dr. Karen Burgess

Chocolate while tasty to humans can be toxic to dogs and cats.  Found commonly in candy, baking products, and cocoa bean mulch, it is often not difficult for household pets to be exposed.

What makes chocolate toxic?
Chocolate contains the toxic methylxanthines theobromine and caffeine.  Both of these agents medically dilate blood vessels, relax smooth muscles, stimulate the heart, and act as diuretics.  Theobromine tends to be the more toxic.

What products contain chocolate?
Cocoa powder, semi sweet, dark, white, and milk chocolate all contain varying amounts of theobromine/caffeine.  More recently the use of cocoa beans as mulch has also caused problems for dogs.

What problems does chocolate cause in dogs?
Methylxanthines stimulate the nervous system, cause fluid changes in the body, and affect contractility of heart and skeletal muscles.

How much chocolate does it take to cause problems?
As little as 9 mg of theobromine per pound of body weight can result in milder signs of toxicity.  Toxicity is severe above 25 mg of theobromine per pound and may be life threatening at doses of 130 mg of theobromine per pound of body weight.  As a reference, baking and some dark chocolates contain 130 to 450 mg of theobromine per ounce of product.  At the other end of the spectrum, milk chocolate typically contains 50 mg of theobromine per ounce and mild chocolate a mere 0.25 mg of theobromine per ounce.  This means that even a half pound of milk chocolate can cause major health problems for a dog.  Two small squares of Bakers chocolate would be a major concern in a dog as big as 60#.

Signs of chocolate toxicity
Common signs include vomiting, diarrhea, increased thirst/urination, agitation/restlessness, elevated heart rate, and seizures.  Sudden death can occur in particular in pets with underlying heart disease.

What to do if your pet ingests chocolate
Contact your veterinarian, animal emergency hospital, or animal poison control immediately.  Be prepared to provide specific information regarding ingestion; product name, amount/weight, ingredients including type of chocolate.  Unfortunately it may take several hours for symptoms to develop and they may then last for several days.  Theobromine is re-absorbed through the bladder wall allowing for re-introduction of the toxin to the body.  Do not induce vomiting unless under the direction of a veterinarian as aspiration may be a concern.  Decontamination, hospitalization, intravenous fluid therapy, indwelling urinary catheterization, and heart monitoring may all be indicated.