Dogs love chocolate. However, because they do not have the proper enzymes to break down the components, it is a poison when ingested.
Chocolate is made from the beans of the cacao tree. Within the beans is Theobromine which is toxic to dogs. Theobromine stimulates the Central Nervous System as well as the cardiovascular system. It also increases blood pressure and causes nausea and vomiting.
Certain types of chocolate are more toxic than others. The most dangerous is unsweetened chocolate commonly used by bakers which contains eight to ten times the amount of Theobromine as milk chocolate. White chocolate contains the least Theobromine, and therefore, poisoning from white chocolate is highly unlikely.
According to the Merck Veterinary Manual 8th edition, unsweetened chocolate consists 290-450 mg of Theobromine per ounce where milk chocolate only consists of 44-60 mg. A toxic dose of Theobromine is approximately 100-200 mg/kg. However, the ASPCA (American Society for the Prevention of Cruelty to Animals) reports having incidents of toxicity where much less amounts were consumed, 20 mg/kg. According to these figures, if a 50 pound dog consumed 5 ounces, there is risk for poisoning.
Signs of toxicity are generally seen within twelve hours. They include nervousness, excitement, trembling, vomiting, diarrhea, excessive thirst, urination, muscle spasms, seizures, coma, and death. While comas and death are rare, they do occur normally due to an abnormal heart rhythm.
If a dog is suspected of ingesting chocolate, a veterinarian should be consulted for advice. Since the toxicity of chocolate is dependent upon the dose, factors such as the type of chocolate, amount eaten, and size of the pet need to be taken into consideration.
While there is no specific treatment, actions can be taken to reduce the negative symptoms. An IV can be started to provide fluids and help prevent dehydration while simultaneously assisting to rid the Theobromine from the body. Emetics which induce vomiting are effective when consumption has occurred within the past four hours. Activated charcoal can be effective for consumption which has occurred beyond the past four hours. Anti seizure can also be of assistance in treating seizures or muscle tremors, and cardiac medication can help regulate a more normal rhythm.
Chocolate is not poisonous to humans because they have the proper enzymes to break down the molecules in Theobromine and digest it properly. Since dogs do not have these facilities, caution must be taken to ensure a dog does no ingest chocolate.