Easter baskets filled with chocolates and eagerly awaited by children could be lethal to pets.

Chocolate contains theobromine. Even small amounts can cause vomiting and restlessness in pets, and larger amounts can cause their death.What is a lethal dose of theobromine depends on the size of the animal and the type of chocolate. Ounce for ounce, baking chocolate has six to nine times more theobromine than milk chocolate.

The Journal of the American Animal Hospital Association reports the death of a springer spaniel after eating a 2-pound bag of chocolate chips.

Few pet owners realize the toxic potential of chocolate, Dr. Aaron Glauberg, a West Orange, N.J., veterinarian wrote in the journal.

"When pets are finally taken to veterinarians," he says, "they are often in more advanced states than if they had eaten something obviously toxic, like rat poison."

As little as 4 ounces of milk chocolate or one-half ounce of baking chocolate can be lethal for a small dog such as a Chihuahua or toy poodle, according to the journal.

Chocolate poisoning occurs less often in cats because their eating habits are different.