I too give our pups an occasional bit of chocolate - usually as part of something else, like cake. Before I did I checked with Cornell University's vet school publication on it:
Chocolate toxicity: What should I do if my dog eats chocolate?
24/7 emergency hotlines:
Pet Poison Helpline: 855-764-7661
ASPCA Animal Poison Control Center: 888-426-4435
One of the most common toxicities in dogs is caused by chocolate ingestion. Dogs cannot metabolize chocolate in the same way people can, so keeping chocolate or products containing caffeine in a secure location out of your dog’s reach is essential. The amount ingested that can cause toxicity depends on the size of the dog and the type of chocolate, with darker and more bitter chocolates being the most toxic. If your dog accidentally ingests chocolate, contact an emergency veterinarian immediately.
Cause
Two toxic components to dogs found in chocolate are caffeine and theobromine, which predominately cause stimulation of the central nervous system and heart. They also act as diuretics, which can quickly lead to dehydration. Dogs may also be at risk for developing gastrointestinal distress or even pancreatitis because many chocolate products are high in fat and sugar.
The amount of theobromine and caffeine in a chocolate product varies, but generally, the darker the chocolate, the higher the risk to dogs. The potential for toxicity is highest in cocoa powder, followed by unsweetened (baker’s) chocolate, semisweet and sweet dark chocolate, milk chocolate and cocoa bean hulls. For example, one ounce of milk chocolate per pound of a dog’s body weight can be deadly compared to unsweetened baking chocolate, where as little as 0.1 ounces per pound of a dog’s body weight may be lethal. For this reason, even ingesting small amounts, especially in a smaller dog, should be treated as an emergency.
Even the worst chocolate - baking chocolate - (who gives their dog baking chocolate) requires a fair amount to be lethal. Our 85lb lab would need 8.5 oz of the worst kind. Reality, like JRHILL, they actually get something like .1oz in a chocolate cookie or piece of cake.