Why Do Dogs Get Sick From Eating Chocolate? It's a known fact that dogs can get sick and even die from eating chocolate, yet in humans a chocolate fix doesn't seem to do much harm. Every year, when holidays like Christmas, Easter, Valentine's Day and Halloween are around the corner, veterinarian hospitals and animal emergency centers are flooded with phone calls of dogs who have eaten chocolate. Understanding why chocolate adversely affects dogs can help dog owners recognize the importance of keeping chocolate away from their beloved companions.
A Matter of Methylxanthines
Chocolate toxicity in dogs is due to the presence of "methylxanthines"a class of alkaloid moleculesfound in caffeine and theobromine, both key components of chocolate. According to an article from Interdisciplinary Toxicology, the most problematic toxin is the methylxanthine alkaloid theobromine, the compound that mostly characterizes chocolate, which is particularly concentrated in cocoa powder and baker's chocolate. Caffeine is far less problematic considering that there is six to ten times more theobromine in chocolate than caffeine. Generally, the darker and richer in cocoa solids the chocolate, the more dangerous to dogs. A list of the total concentration of methylxanthine in chocolate can found here: Table 1.
A Slower Metabolism
Why does chocolate hurt dogs when humans can generally eat it without suffering any adverse effects? Turns out, it's a matter of metabolism. Dogs metabolize theobromine more slowly compared to humans and they fail to excrete it efficiently.
This allows theobromine to stick around the dog's system longer and cause harmful effects. According to Nancy Lowry, a Professor of Chemistry at Hampshire College, Amherst, MA, the half-life (the time it takes for half of a substance to be eliminated from the bloodstream) for theobromine in dogs is 17 to 18 hours, while in humans it's 6 to 10 hours after consumption. According to the Merck Veterinary Manual, theobromine and caffeine are quickly absorbed from the gastrointestinal tract and are widely distributed throughout the dog's body.
Effects on Dogs
Once ingested in a toxic amounts, theobromine wrecks havoc in the dog's body. While theobromine is a mild stimulant in humans, in dogs it stimulates the central nervous system and cardiovascular system, triggers a diuretic effect and slightly increases the dog's blood pressure. Symptoms are likely to occur within two hours of ingestion, but, because theobromine is metabolized slowly, symptoms may show up even as long as 24 hours.
At low levels, affected dogs may exhibit the following symptoms: nausea, vomiting, diarrhea, increased drinking, increased urination and hyperactivity. Some susceptible dogs may develop symptoms of pancreatitis from the fat content in chocolate. At higher levels, symptoms may progress and dogs may develop nervous system disorders and electrolyte abnormalities, muscle twitches, seizures and cardiac arrhythmias which can turn fatal. Symptoms of chocolate toxicity generally show up in dogs within 6 to 12 after ingestion.
Treatment is Supportive
There is no specific antidote to give to a dog who has ingested chocolate. If the ingestion was fairly recent, generally within one to two hours, before symptoms appear, the dog can be induced to vomit by giving hydrogen peroxide as outlined by veterinarian Dr. Adrienne Mullinger. Other than inducing vomiting, treatment for dogs who have ingested toxic amounts of chocolate include supportive care through the administration of activated charcoal, oxygen, and intravenous fluids. Dogs with seizures are given benzodiazepines or barbiturates while dogs with arrhythmias are given antiarrhythmics. In severe cases, symptoms may persist for up to 72 hours. If your dog ate chocolate consult with your vet.
Did you know? According to VCA animal hospitals, white chocolate rarely causes chocolate poisoning. With only 0.25 mg of theobromine per ounce the risks for toxicity are quite low, but its fat content may still cause pancreatitis in susceptible dogs.