The harm depends on the type of chocolate, the intake of pets and the size of pets. Enough chocolate or cocoa products are fatal to pets.

The toxic ingredient in chocolate is theobromine. Humans can metabolize theobromine easily, but cats and dogs metabolize theobromine much more slowly, so it is easy to accumulate in the body to a toxic level.

A small amount of chocolate may only make dogs feel stomach upset, vomiting or diarrhea. A large amount of theobromine can cause muscle tremor, spasm, arrhythmia, internal bleeding or heart disease. The typical symptom of theobromine poisoning is severe ADHD.

Theobromine contained in chocolate is the main factor leading to dog poisoning. A dog weighing one kilogram may die if he eats 9 grams of pure chocolate.

The symptoms of chocolate poisoning include vomiting, diarrhea, frequent urination, anxiety, hyperactivity, rapid heartbeat and breathing, and even ataxia (unstable walking), cyanosis, arrhythmia, spasm, and even death due to loss of cardiovascular function.

Extended data:

Chocolate is made from cocoa beans and contains many derivatives of methylxanthine, including caffeine and theobromine. These substances will combine with some receptors on the cell surface, thus preventing natural substances in animals from combining with receptors.

Taking a small dose of this substance, dogs will vomit and diarrhea, while humans will have euphoria. Chocolate contains a lot of theobromine and a little caffeine. If the dog eats too much chocolate, it will have muscle spasm and even shock. After taking theobromine and caffeine, the dog's heart rate will suddenly rise to more than twice the usual level, and some dogs will run around like drinking a large cup of espresso.

Sugar-free baked chocolate contains more than six times as much methylxanthine as cream chocolate. According to experts, for some small dogs, 4 ounces (about120g) of cream chocolate may be a fatal dose. If you only eat a small amount of chocolate, the puppy can resist and not bother the vet.

If you eat too much, you have to force it to eat activated carbon to remove methylxanthine from chocolate and avoid entering the blood circulation through the digestive system. Although chocolate can't kill the dog instantly, the owner should feed the dog less chocolate.

References:

People's Network-Dogs can't eat chocolate. Is it a deadly poison?