Chocolate and Companion Animals
Chocolate and cocoa are derived from the beans of the Theobroma cacao tree, which is of South American origin. Chocolate and cocoa contain two toxic methylxanthine stimulants, theobromine and caffeine, which can be fatal to domestic animals if eaten in excess. Dogs are especially sensitive to theobromine, and cats are slightly more sensitive to caffeine. Unsweetened baking chocolate is the most dangerous to companion cats and dogs, because it is so highly concentrated. Baking chocolate often contains more than 400 milligrams of theobromine per ounce, while ordinary milk chocolate only contains between 44 and 60 milligrams per ounce. Reported sources of theobromine include:
||Concentration (mg of theobromine/ounce):
|Unsweetened baking chocolate
|Dark semisweet chocolate
|Cacao bean hulls
|Cacao bean mulch
Dogs are more likely to become poisoned by eating chocolate than cats, for several reasons. First, dogs seem to be especially fond of the taste of chocolate. They also tend to get into garbage, “counter-surf” and rummage through grocery bags, backpacks, cupboards and purses in search of tasty tidbits, which may include chocolate. Dogs are fairly indiscriminate eaters and can easily consume an entire bag of chocolate candy or a plate of chocolate cookies very quickly. Cats, on the other hand, tend to be much more discriminating about their dietary selections. In addition, toxicological studies have shown that dogs are especially sensitive to theobromine when compared to other domestic animals. Dogs metabolize theobromine very slowly, which causes the substance to stay in their blood streams for an unusually long time. This may be true to a lesser degree in cats. However, because cats are less apt to eat chocolate, less research on feline chocolate toxicity has been published. Pets – especially dogs - can also become poisoned if the eat the cacao bean hulls that are frequently used as landscape mulch or bedding, although fortunately most of those cases aren’t fatal.
What Chocolate Does to Pets
Both theobromine and caffeine stimulate the central nervous system and heart muscle. They also relax smooth muscle, especially bronchial muscle, and increase the production and excretion of urine by the kidneys. Even small amounts of chocolate can cause adverse reactions in our cats and dogs. Most of the time, the signs of chocolate poisoning come on suddenly (acutely) and include:
- Nervous system stimulation
- Elevated heart rate (tachycardia; marked)
- Irregular heart beat (arrhythmia; premature ventricular contractions)
- Rapid breathing (tachypnea)
- Open-mouth breathing (panting)
- Difficulty breathing (dyspnea)
- Frequent urination
- Urinary incontinence
- Bluish discoloration of skin and mucous membranes (cyanosis)
- Muscular rigidity
- Lack of coordination (ataxia)
- Sudden death
Clinical signs of chocolate toxicity may not appear for several hours after the animal has eaten the chocolate. However, the onset of symptoms usually will be obvious within 4 or 5 hours, and will continue for 12 to 36 hours. A dose of 250-500 milligrams of theobromine per kilogram of body weight is considered to be potentially lethal to dogs; the lethal dose in cats ranges around 200 milligrams per kilogram of body weight. The signs of chocolate poisoning usually progress rapidly. Death from respiratory and/or cardiac failure can occur up to several days after the chocolate was consumed.
If given the opportunity, many dogs and some cats will eat as much chocolate as they can find. For this reason, all foods containing chocolate, including candy, cake, cookies, cocoa powders and chocolate beverages, should be safely stored in places that are inaccessible to pets. This is especially important during the holidays and on other festive occasions such as birthdays, Easter and Halloween, when many people set out candy dishes and platters of baked goods. When a pet is known or suspected to have gotten into chocolate or cacao-containing products, its owner should consult with a veterinarian immediately. Blood tests can detect dangerously elevated levels of theobromine, although many times the presumptive diagnosis is made based on the animal’s clinical signs and history of access to chocolate. Treatment goals including providing basic life support and stabilization, preventing further absorption of theobromine, increasing the excretion of theobromine and providing supportive care for patients with seizures, respiratory distress and/or heart abnormalities. The veterinary team can induce vomiting to empty stomach contents if the chocolate was eaten recently. Sedation and use of a ventilator can help stabilize respiration. Activated charcoal is commonly used to bind the chocolate, prevent further absorption of theobromine and increase its excretion. Intravenous fluids can be administered to speed up the excretion of theobromine in the urine. A number of different medications are available to help regulate heart and respiratory activity. Even with quick veterinary attention, it may take a pet several days to recover completely, and unfortunately not all of them will survive.