Chocolate Poisoning in Dogs

I've heard that chocolate is toxic to dogs? Is this true?

Yes, chocolate is toxic to dogs (and cats). Eating chocolate often results in illness, and if the dog eats enough, it can be fatal. Chocolate is toxic because it contains the alkaloid theobromine. Theobromine is the predominant toxin in chocolate, and its actions are similar to caffeine. Theobromine may be used medicinally as a diuretic, heart stimulant, blood vessel dilator, and a smooth muscle relaxant. Dogs cannot metabolize theobromine or caffeine as well as people can. It can be poisonous in large amounts, and the toxic dose depends upon the size of the dog. 

chocolate_poisoning-1_-_2009How much chocolate is poisonous to a dog?

The ASPCA poison control center reports that if a dog eats as little as 20 mg/kg of body weight (or 10 mg/lb), it can show significant signs of illness. Toxic doses of theobromine are reported to be about 100 mg/kg (approximately 50 mg/lb) and fatalities occur at around 200 mg/kg (approximately 100 mg/lb). 

The amount of toxic theobromine varies with the type of chocolate. The darker and more bitter the chocolate is, the more dangerous it is to the dog. Baking chocolate and high quality dark chocolate are highly concentrated in theobromine, and contain between 15-20 mg of theobromine per gram of the product (130-450 mg per ounce), while regular milk chocolate only contains about 1.5 mg/gm (44-58 mg/ounce.  White chocolate barely poses any toxic threat as it only contains trace amunts of theobromine (about 0.25 mg/ounce). However, dogs can still get a severe case of pancreatitis from eating white chocolate because of all the fat and sugar.

Doing the math, a healthy small dog, weighing 4.5 kg (10 pounds), could show signs of mild illness if it ate 5-6 gm (1/6 oz) of baking chocolate or a 2 ounce milk chocolate bar. The toxic amount of chocolate for the same 4.5 kg (10 pound) dog would be only 28 gm (1 ounce) of baking chocolate or gourmet dark chocolate, or 330 gm (12 ounces) of milk chocolate.

A healthy medium sized dog, weighing 23 kg (50 pounds), would show signs of illness if it ate about 28 gm (1 ounce) of baking chocolate or 300 gm (10.7 ounces), while the toxic dose for this size of dog would be around five ounces (140 gm) of baking or dark chocolate or 3.25 pounds (1.5 kg) of milk chocolate. 

However, the toxic dose of chocolate for a pet that is older or has other health problems will be lower (i.e. a dog with a pre-existing illness or a geriatric dog may be more sensitive to the effects of theobromine).

What are the clinical signs of chocolate poisoning?

Clinical signs depend on the amount and type of chocolate that is eaten.

At doses of around 20 mg/kg, agitation or hyperactivity (panting or restlessness), and gastrointestinal signs (such as drooling, vomiting, and diarrhea - all of which may smell like chocolate) predominate. At doses over 40 mg/kg, cardiac signs will be seen, including a rapid heart rate, elevated blood pressure, and in some casese heart arrhythmias (abnormal beats). At doses of more than 60 mg/kg, neurologic signs such as tremors, muscle spasms, twitching, and even seizures are common. Fatalities occur in healthy dogs that eat 200mg/kg of theobromine, or in dogs that have other pre-existing illnesses or are geriatric. Complications, such as developing aspiration pneumonia from vomiting, can worsen the prognosis. 

Clinical signs of chocolate poisoning can take up to twelve hours to develop, and can last for days due to the long half-life of theobromine. Once theobromine is absorbed into the body, it may remain in an active form for up to twenty-four hours. It is important to seek medical attention, either from your veterinarian or by calling the Pet Poison Helpline (available 24/7 for a fee at 1-800-213-6680) as soon as you suspect that your dog has eaten chocolate. 

Are there other problems associated with eating chocolate?

Yes. if the product contains a high amount of fat or a lot of sugar, it can trigger a bout of acute pancreatitis, an inflammatory condition of the pancreas (for more information, see our handout "Pancreatitis in Dogs"). Symptoms of pancreatitis include nausea, vomiting, fever, lethargy, abdominal pain, diarrhea and decreased appetite. If acute pancreatitis develops, more intensive treatment will be needed.

What should I do if my dog eats chocolate?

Since chocolate is potentially toxic to dogs, you should contact your veterinarian to see whether your individual dog is at risk for developing toxicity or other complications. If you suspect that a toxic amount of chocolate was eaten, you must have your pet examined by a veterinarian immediately. The sooner the theobromine is removed from the body and the dog's condition is stabilized, the better your dog's prognosis.

What is the treatment for chocolate poisoning?

Treatment depends on the amount and type of chocolate eaten. If treated shortly after eating the chocolate, the only treatment that your veterinarian may give will be to administer medications to induce vomiting so that any chocolate in the stomach will be vomited up, and to give activated charcoal to block absorption of any chocolate that is in the intestinal tract. In cases where the chocolate was ingested several hours earlier, activated charcoal may be administered to block further absorption of theobromine in the stomach and small intestine. Since theobromine can be re-absorbed from the bladder, your veterinarian will recommend that your dog be put on intravenous fluids and taken for frequent walks to dilute the urine and promote elimination by urination. Activated charcoal may be administered every four hours for the first twenty-four to thirty-six hours to reduce the continued resorption and recirculation of theobromine. 

It is very common to provide supportive treatments such as intravenous fluid therapy to stabilize your dog, dilute the toxins and promote its excretion through urination. All dogs that have eaten chocolate should be closely monitored for the first twenty-four hours for  continued vomiting or diarrhea, nervousness or other neurologic signs, or increased or irregular heart rate. It may be necessary to give heart medications if the heart rate is abnormal. 

If there is evidence of acute pancreatitis, your dog may require more intensive treatment.

I saw a treat made for dogs that contained chocolate. Isn't that dangerous?

Many gourmet dog treats use carob as a chocolate substitute. Carob looks similar to chocolate and the two are often confused. Some specialty dog bakeries will use a small amount of milk chocolate in their treats. Since the amount of theobromine is so low in milk chocolate, this MAY be safe for most dogs. However, most veterinarians recommend that you avoid giving your dog chocolate in any form.

If you enjoy eating or cooking with chocolate, particularly if you are a fan of dark chocolate, you should be extremely careful to keep these products out of raach of your pet. Also, be very careful if you enjoy dietetic chocolate or any other candy that is sweetened with xylitol, as xylitol is EXTREMELY TOXIC TO DOGS. 

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