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Why Is Chocolate Bad for Dogs?

dog sick from chocolate
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Almost every pet parent can tell you that chocolate is bad for dogs. Yet, many are not actually aware of why exactly chocolate is bad for dogs. How can something that tastes so good to us be so harmful to our dogs?

Let’s discuss the science behind chocolate toxicity in dogs, what happens if a dog eats chocolate, and what you should do if you catch your canine companion with their paw in the metaphorical chocolate chip cookie jar.

Can Dogs Eat Chocolate?

No, dogs should absolutely never eat chocolate. Chocolate is a toxic food for dogs, and depending on your dog’s size and the type and amount of chocolate they ate, it could cause a serious medical emergency. 

While chocolate ingestion in dogs is rarely fatal, it can be if they eat enough. Even small amounts of chocolate can make your dog sick. 

Dog owners should avoid giving their dogs any people food that contains chocolate, or leaving their dog unsupervised around any tempting chocolaty goodies. 

Why Is Chocolate Bad for Dogs?

Different types of chocolate

Chocolate is bad for dogs primarily because it contains two methylxanthines compounds: theobromine and caffeine. 

Theobromine poses a more serious risk to dogs, but both are problematic. Dogs cannot metabolize these compounds easily like humans, so they build up in their system and cause clinical signs of chocolate toxicity. 

Some chocolate varieties and candies are made sugar-free and sweetened using a substance called xylitol, which is also toxic to dogs. 

Types of Chocolate and Their Danger Levels

Different types of chocolate contain different levels of theobromine and caffeine. Below is a breakout of the types and the dangers they pose to dogs:

Dark Chocolate and Baker’s Chocolate: Chocolate varieties that are more pure, such as dark chocolate and baker’s chocolate, contain higher levels of these compounds, making them more dangerous for dogs than other types of chocolate. These chocolates are often used when baking and cooking, so pet parents should take extra precautions when working with dark chocolate. 

Milk Chocolate: Milk chocolate contains less theobromine and caffeine per ounce, but can still cause serious illness if enough is ingested. Keep milk chocolate candy away from dogs to prevent ingestion.

White Chocolate: White chocolate contains hardly any theobromine or caffeine, and is not nearly as dangerous as other chocolate varieties.

While milk chocolate and white chocolate contain less theobromine and caffeine, they do contain higher levels of sugar and fat. Although not necessarily toxic themselves, these ingredients can cause gastrointestinal upset and trigger serious illnesses like pancreatitis

What Happens if a Dog Eats Chocolate?

Dog eating chocolate on counter

Ultimately, what happens if your dog eats chocolate will depend on their body weight, the amount of chocolate they ate, and the type of chocolate they ate. 

Both theobromine and caffeine affect nearly the entire body by increasing the heart rate, causing diuresis (increased urine production), dilating blood vessels, relaxing smooth muscle, and stimulating the nervous system. 

If your dog only consumes a small amount of chocolate (proportionately to their body size), the signs will likely be limited to the gastrointestinal system like vomiting and diarrhea

Larger doses of chocolate consumed by dogs will result in gastrointestinal upset in combination with more serious symptoms, such as:

  • Panting
  • Tremors
  • Restlessness
  • Increased heart rate
  • Cardiac arrhythmias
  • Seizures
  • Collapse
  • Death

Symptoms of chocolate toxicity do not show up immediately. Since dogs do not metabolize theobromine and caffeine efficiently, they continue to build up as they are released by the digestive system, and signs of chocolate toxicity can continue to worsen over time. Without treatment, these symptoms can last for days as the affected dog’s body slowly breaks down the toxins.

Dog Chocolate Calculator 

If you know exactly how much chocolate your dog ate, what type of chocolate they ate, and your dog’s weight (in kilograms), it is possible to calculate whether or not they will develop any form of chocolate toxicity. 

Step 1: Determine Theobromine Per Ounce

Type of ChocolateTheobromine Range (milligrams per ounce)
Cocoa Powder130 – 450 mg/ounce
Baking Chocolate130 – 450 mg/ounce
Dark Chocolate130 – 450 mg/ounce
Milk Chocolate44 – 58 mg/ounce
White Chocolate0.25 mg/ounce

Note: It’s best to always use the maximum amount of theobromine in your calculation so you don’t underestimate the dose. 

Step 2: Convert Pounds to Kilograms

To convert your dog’s weight to kilograms you divide their weight in pounds by 2.205. You can also use the chart below.

Dog’s Weight (pounds)Dog’s Weight (kilograms)
10 pounds4.53 kilograms
20 pounds9.07 kilograms
30 pounds13.60 kilograms
40 pounds18.14 kilograms
50 pounds22.67 kilograms
60 pounds27.21 kilograms
70 pounds31.75 kilograms
80 pounds36.28 kilograms
90 pounds40.82 kilograms
100 pounds45.35 kilograms

Step 3: Do the Calculation

Plug your numbers in using the following formula:

(Theobromine per ounce x ounces consumed) / Dog’s weight (in kilograms) = Dose of theobromine

Step 4: Understand Theobromine Dose Results

The result of your calculation can help you understand whether or not to go to the veterinarian. Any result greater than 20 mg/kg requires immediate veterinary intervention and treatment.

Theobromine Dose (milligrams per kilogram of body weight)Chocolate Toxicity Symptoms
100 mg/kgFatal (some dogs can die from lower doses)
20 mg/kgRestlessness, panting, cardiac abnormalities, gastrointestinal signs
10 mg/kgGastrointestinal upset such as vomiting and diarrhea

Chocolate Toxicity Calculation Example

Let’s say your dog weighs 22 pounds (or 10 kilograms), and you find out they ate a standard sized milk chocolate Hershey’s bar which is 1.55 ounces. 

Multiply the ounces of milk chocolate (1.55 ounces) by the concentration of theobromine in milk chocolate (58 mg/oz). This comes to 89.9 mg of theobromine consumed. 

Now you simply divide this number by your dog’s weight in kilograms (10 kg). So 89.9 mg of theobromine divided by 10 kilograms of body weight comes out to a dose of 8.99 mg/kg of theobromine. 

Here is the calculation example written out: (58 mg/oz x 1.55 oz) / 10 kg = 8.99 mg/kg.

At this dose, your dog will likely be okay, although you should expect them to have some vomiting, diarrhea, loss of appetite, or lethargy for a day or so since this is very close to the 10 mg/kg level of toxicity that causes gastrointestinal upset. 

What to Do If Your Dog Eats Chocolate

Dog at vet for chocolate poisoning

If your dog ate chocolate, do not wait and see whether or not they develop symptoms of toxicity. 

Start by calculating the ingested dose if you are comfortable using the directions above. If you are not comfortable performing the calculation or do not know how much chocolate your dog ate, call your veterinarian, the local emergency clinic, or Pet Poison Helpline for advice. Alternatively, you can simply bring your dog to a veterinary clinic or emergency veterinarian for evaluation and treatment if needed. 

Oftentimes, pet parents aren’t sure how much chocolate a dog ate, and a calculation of the dose they consumed isn’t possible. In these cases, it’s best to treat the dog quickly rather than taking a “wait and see” approach. 

When you are taking your dog to the veterinary clinic, be sure to bring any wrappers or packaging of what they ate, as that can help determine the maximum amount of theobromine they may have consumed. 

It’s always best to have dogs treated within the first hour of consumption, before digestion has taken place. This means the stomach contents can be emptied before the toxic compounds are released into their system. 

Treatment for chocolate toxicity can vary greatly depending on the dose a dog consumes, but starting treatment sooner rather than later always results in the best outcome for your pet and a lower cost to you. 

How to Prevent Chocolate Toxicity in Dogs

Chocolate toxicity in dogs can be easily prevented by ensuring that your dogs never have the opportunity to consume chocolate or chocolate-containing goodies. 

Here are some simple ways to keep dogs away from chocolate:

  • Never leave your dog unsupervised in an area where chocolate is within reach.
  • Teach your dog to “leave it” or “drop it” so you can intervene if you see them about to snack on dropped chocolate.
  • Store all chocolate items on the highest shelf in a closed off pantry. 
  • Put a dog gate at the kitchen door to keep dogs away from food.
  • Do not leave tempting chocolate treats in decorative bowls or under the Christmas tree during the holidays. 
  • Make sure your children and guests know that chocolate can be harmful to dogs so they don’t share anything potentially dangerous.

Dogs and Chocolate: FAQs

Can chocolate kill dogs?

Yes, if dogs consume chocolate in great quantities, they can die. However, death from chocolate ingestion in dogs is rare. Fast treatment can offer dogs a better prognosis and outcome. 

How much chocolate can kill a dog?

A fatal dose of chocolate for dogs is 100 milligrams of theobromine per kilogram of body weight. However, some dogs may die from smaller doses of theobromine. Different types of chocolate have different levels of theobromine. Dogs are more likely to die or experience serious complications if they consume dark chocolate, baker’s chocolate, or cocoa powder. 

Can dogs eat white chocolate?

While white chocolate is not as toxic as milk chocolate or dark chocolate, it is still not recommended for dogs. White chocolate contains high levels of fat and sugar, which can lead to pancreatitis and other gastrointestinal problems in dogs.