There are many different formulations of chocolate, with varying amounts of caffeine and theobromine. The mildest form is sweet milk chocolate, and the strongest form is the dark bitter product called baker's chocolate. The lethal dose of sweet milk chocolate for a dog is two ounces per kilogram of body weighs. For an 11-pound dog, this would be about 10 ounces. A lethal dose of milk chocolate for a 55-pound dog would be about 50 ounces, or just little over three pounds.

The darker baker's chocolate is at least ten times as lethal. A 55-pounddog could die from the methylxanthines in 5 ounces of baker's chocolate.

A typical poisoning incident happens around Easter or Christmas, when there are a lot of chocolates around the house. 

Symptoms of methylxanthine poisoning include vomiting, hyperactivity, restlessness, hypersensitivity to touch (the dog will jump when touched), very rapid heartbeat and breathing rate, a loss of control of leg muscles, muscle tremors, then seizures, general weakness, coma and while rare, death can occur, usually due to the adverse action of methylxanthines on the heart. 

The vet works to clear the chocolate from the dog's stomach, administers activated charcoal and other substances to absorb the poisons, keeps the dog's fluids under control and applies other supportive measures if necessary

Keep These Numbers Handy

The National Animal Poison Control Center can be reached at 1-800 548-2423. If you call this number, have your credit card ready. The flat fee for following your case is $30, which can be reimbursed.

Another way to reach the NAPCC is to call 1-900-680-0000 This really is the number!). The first five minutes is $20, with a charge of $2.95 per minute there after. These charges are not reimbursable.

The NAPCC asks that you always call the 800 number first. They will direct you to the 900 number if need be, but they say this is generally not necessary.

Both numbers get to the same place. When you call either one of them, you will be put into immediate contact with a veterinary toxicologist, and you will be asked to provide the following information:

On a personal note, even though the darker, baking chocolate contains more theobromine, my mini long, who is a "chocoholic" and seeks it however she can find it, did manage to get a jumbo sized Hershey Kiss off the counter.  (How? we figure one of the dogs levitated her somehow or assisted in the plan since there was no conceivable way she could have gotten it herself) But, even though it was a milk chocolate, she ingested enough so that when we came home we witnessed a mini running tracks around the house, up walls, up furniture, bouncing higher than a pogo stick. The only clues were some red foil in a little tiny ball, chocolate colored and smelling vomit everywhere,  and the most powerful "chocolate breath" exhuding from her little hyperactive body.  We found no remains of the jumbo kiss, and with the clue that she had to have eaten it, and her amazing strength she had trying to wiggle out of my arms, I called the emergency clinic (yes, it was 11:00PM) and told them I was on my way.  Have you ever seen a dog run circles in a carry crate? Chocolate will do it!   The Vet, having listened to her vitals, said her heart was racing, she was having a caffeine overdose, was so hyperactive she was impossible to even hang on to, her eyes were showing nastagma (rapid movement back and forth), but, he felt she just needed to get it out of her system because she was actually coming "down" from her chocolate binge and therefore didn't feel we needed to pump her stomach or administer the charcoal treatment. (she had vomited quite a bit)  My duty was to watch her and make sure she continued to return to normal, but if there was a change to a negative effect, then to get her right back in there. Fortunately, he was right and she was beginning to calm down, and by morning she had become her normal, silly, self.  In hindsight I probably would have been smart to have strapped pledge and a dust rag to her so she could have done a little cleaning while she was in her "up on everything, around the walls" mode.