Theobromine, a naturally occurring alkaloid fond in the cocoa bean, can be harmful even in small amounts. Theobromine can cause vomiting and restlessness in pets. Larger doses can be fatal.
The lethal dose of theobromine depends on the size of the dog and the type of chocolate. Ounce for ounce, baking chocolate has 6 to 9 times as much theobromine as milk chocolate.
Estimates of the smallest amounts that can be fatal are:
4 to 10 ounces of milk chocolate or ½ to 1 ounce of baking chocolate for small dogs, including chihuahuas or toy poodles.
1 to 1 ½ pounds of milk chocolate or 2 to 3 ounces of baking chocolate for medium sized dogs, including cocker spaniels and bulldogs
2 to 4 ½ pounds of milk chocolate or 4 to 8 ounces of baking chocolate for large dogs, including collies and labrador retrievers.
Some of these signs noticed in your pet should be seen by a veterinarian immediately:
Vomiting or diarrhea
Cats have much different eating habits and seldom are poisoned by chocolate. Cat owners, nonetheless, should keep chocolate well out of reach.