Why is Chocolate Bad for Dogs & Other Animals (+ How Much)?

Chocolates are a popular treat, and they give off an aroma that’s attractive even to our pets. However, you shouldn’t give chocolate to dogs, especially smaller breeds, and in this article we cover why chocolate is bad for dogs and how much can end up being fatal.

Note that if you are in an emergency situation where you pet has eaten chocolate, you should call your vet immediately and follow their advice.

Why Chocolate is Bad For Dogs

Chocolate contains caffeine and theobromine, both of which affect the central nervous system, cardiovascular system, and respiratory system. The effects of these stimulants are more potent in dogs, who have a smaller body weight and a metabolism that can’t process theobromine as well as ours can.

For context, the estimated half-life of theobromine in humans is 2 - 3 hours— in dogs it’s up to 18 hours. The stimulants can cause a dog’s heart to beat very quickly, inflame their intestines, increase blood flow, cause and exacerbate bleeding and bruising, induce vomiting, and eventually cause death.

Theobromine toxicity on dogs is different from a chocolate allergy.

In an acute toxicity study of male mongrel dogs, symptoms appeared within 4 to 5 hours of theobromine administration (a proxy for eating chocolate). The sample dogs given theobromine doses at 200 mg/kg body weight didn’t experience fatalities, however 3 out of 14 died from a sample of dogs given between 300-1000 mg/kg body weight.

What Happens if a Dog Eats Chocolate?

Chocolates are a source of caffeine and theobromine, both methylxanthines, stimulants that block adenosine from reaching the brain receptors which trigger sleepiness (caffeine is more effective at this). These stimulants also increase a dog’s heart rate.

Theobromine in particular is a diuretic, and causes them to become dehydrated. The dog can then become excessively hyper or irritable, lose balance or coordination, or develop muscle twitching.

If symptoms progress following a high dose of theobromine, it could lead to an irregular heartbeat rhythm, seizure, or even death within hours. Symptoms can appear as early as 2 hours from ingestion, and as long as 6 to 12.

The first signs of theobromine poisoning (chocolate poisoning) include vomiting, vomiting blood, and excessive thirst.

What to Do if Your Dog Eats Chocolate

If your dog has eaten chocolate, determine the type and amount of chocolate they’ve consumed. Knowing these will give professionals a rough idea as to how much theobromine was ingested. 

Do not wait. Call the vet immediately to confirm if the amount is unsafe, based on your dog’s breed and body weight. If the amount of chocolate the dogs consumed becomes a concern, bring them to a vet immediately. 

The vet may provide medicine to calm your pet’s restlessness, administer activated charcoal to trap some of the theobromine, attempt to induce vomiting, or place the dog on intravenous therapy to hydrate them and get them to urinate.

How Much Chocolate is Toxic to a Dog?

Chocolate toxicity in dogs can be determined based on the amount of theobromine consumed. As such, the type of chocolate and the amount become important indicators. 

Chocolate types vary in cocoa content, and therefore theobromine content. Plain chocolates contain roughly 15 mg/g, while milk chocolate contains about 2 mg/g.

If you can’t get ahold of your vet right away, an online chocolate toxicity calculator can help quickly assess your dog’s situation based on the previously-discussed considerations.

A reference from Merck Veterinary Manual (2006) suggests that 20 mg/kg of body weight exposure to theobromine in dogs is enough to trigger milder symptoms, such as vomiting and diarrhea. 60 mg/kg is said to be enough to manifest cardiotoxic effects.

Greater than 60 mg/kg exposure could result in seizures. The dose of theobromine that’s lethal to dogs ranges between 100 to 500 mg/kg of body weight. The lethal dose of theobromine that will kill 50% of the population of a sample of dogs (LD50) is 300 mg/kg, however deaths have been reported at doses as low as 115 mg/kg.

A 10kg (22lbs.) small breed dog would have a threshold of roughly 1150 mg, and 100 g of dark chocolate would exceed that limit at 1500 mg of theobromine.

Even though milk chocolate and white chocolate contain very small amounts of theobromine, they also contain fats and sugar that can contribute to pancreatitis.

Chocolate Toxicity in Dogs & Other Animals

A 2009 study on the effects of theobromine as a contaminant in feed described the effects of theobromine on a variety of animals. For livestock, adverse effects were found to occur in calves with amounts of theobromine as low as 45-90 mg/kg body weight.

Goats and sheep that were tested ended up with reduced body weights. 

Horses were pretty resilient, showing only dehydration and reduced appetite. For pigs, young pigs lost appetite, became lethargic, dirty, and showed signs of growth retardation. But even older pigs tested showed increased body temperatures, and abnormal behaviors before dying.

Chickens experienced lower appetite after consuming theobromine, leading to low weight and increased mortality. 80 out of a test population of 300 hens died of convulsions, while the remaining had decreased appetites and decreased egg production.

Rabbits became anorexic and experienced gastric problems and cardiac failure, eventually leading to their death, while their litters experienced malformations and increased mortality.

It’s said that theobromine has a greater toxic effect on cats, but it’s generally less of a problem since cats actively do not like chocolate. For fish, a study on tilapia and catfish theobromine exposure didn’t have much effect, and the decrease in weight was attributed to the high fiber content in the husks they were fed. 

However, it’s probably a particularly bad idea to give chocolates to a pet bird. A case report takes note of a male parrot found dead after ingesting about 20g of dark chocolate.

A Swedish study also took note of a red fox and badger being found dead on a golf-course after eating pig feed that incorporated waste chocolate. A 2005 test on using theobromine as a means to control the coyote population revealed that 385 mg/kg of body weight of theobromine ingestion had high lethality.

Chocolate and Dogs FAQ