Agitation, hyperactivity and gastrointestinal upset have been noted when a dog ingests 20 mg per kilogram of body weight. Gastrointestinal upset can include drooling, vomiting and diarrhea that will smell like chocolate. Theobromine toxicity has been fatal when your dog ingests 200 mg per kilogram of body weight.

Theobromine is the main toxin found in chocolate. It is similar to caffeine and has been used medicinally in humans as a heart stimulant, diuretic, blood vessel dilator and muscle relaxant. Dogs are unable to metabolize theobromine and this makes it toxic to them. The darker the chocolate or the more bitter the taste, the more toxic it is to dogs. Gourmet dark chocolate and baking chocolate contain a highly concentrated amount of theobromine which is between 130-140 mg per ounce. Milk chocolate is not as toxic as it only contains about 44 mg per ounce. White chocolate contains 0.25 mg per ounce of theobromine; therefore it does not pose a large risk of theobromine toxicity.

The symptoms of theobromine toxicity in dogs will vary depending on the amount of chocolate that has been ingested and the size of the dog. If you suspect your dog has eaten chocolate, it is best to seek veterinary assistance to ensure that he does not suffer life-threatening effects from the chocolate. Symptoms can take several hours to present after your dog has eaten the chocolate. These symptoms can last for several days. Signs to watch for include:

Theobromine toxicity in dogs occurs when dogs eat chocolate. This toxin is similar to caffeine and has similar effects on the body. Dogs do not metabolize theobromine and can cause severe illness and even death. Dogs should never be fed chocolate of any kind or in any amount. All chocolate should be kept out of reach of your dog. Children should also be made aware that chocolate is dangerous for dogs. 

Dark chocolate, baking chocolate and gourmet dark chocolate are the most toxic to dogs; however, milk chocolate in large doses can cause your dog to become sick. The more cocoa solids that are in the chocolate the more theobromine will be present in the chocolate.

When you bring your dog in for your veterinary appointment, they will ask you about your dog’s medical history and what clinical symptoms that have been noted. If you actually saw your dog eating chocolate, bring the packaging with you to your appointment. 

Your veterinarian will perform a physical examination as well as a complete blood count, biochemistry panel, urinalysis and fecal exam. This will help your veterinarian determine if your dog’s body is suffering adverse effects from the theobromine found in chocolate.

Your veterinarian will suggest a treatment plan with you and if the theobromine toxicity is severe enough, hospitalization may be necessary. Theobromine, once absorbed by your dog’s body, can be difficult to flush and can even be re-absorbed into the body from the bladder.

If you see your dog actually eating chocolate, contact your veterinarian immediately. They may have you induce vomiting right away if you live a far distance from your veterinarian. Inducing vomiting must be done within two hours after your dog eats chocolate. To induce vomiting, you will administer 3% hydrogen peroxide per 10 pounds of body weight. Your dog should vomit within 10 minutes of administering the hydrogen peroxide. Your veterinarian will use a drug, most likely apomorphine, to induce vomiting when you bring your dog into their office.

After inducing vomiting, your veterinarian may administer an activated charcoal solution by mouth. The activated charcoal will absorb any theobromine that is still present in the gastrointestinal tract. 

Your dog will require supportive care including intravenous fluids to dilute the theobromine that has entered the bloodstream. The IV fluids will help flush the theobromine from the body. Anti-arrhythmic medications can be given to stop any heart arrhythmias that are occurring. Valium may also be given to control muscle tremors and seizures.

While it is unlikely your dog will die from eating chocolate, unless he eats a large amount, he can become very sick and require supportive care until the symptoms pass, which can take several days. Do not simply hide chocolate from your dog, place it in a sealed container, or freezer bag, and put it in an upper cabinet where your dog cannot reach.