Death by Chocolate
by Graham Peck
Rags was a boisterous four-legged dustbin easily mistaken for a Labrador. I had the privilege of learning all about chocolate poisoning from him shortly after I qualified as a veterinary surgeon. Rags had pulled an overnight raid on the family Christmas tree. As it was the weekend before the big event the tree was still festooned with tinsel, lights and most important about ten chocolate father Christmases plus a box of similar confectionery delights nestled at its base. The tree had been "felled" and the chocolate plus foil wrappers devoured. Discovered, Rags had been suitably chastised, exiled to his basket and the worst punishment of all - no breakfast.
Later that morning his owner phoned the surgery to report a very unhappy Rags, who had been acting odd, drinking a lot and was now starting to vomit. But the owner advised she was not at all surprised considering the various items that had been consumed. It was decided that a check-up during the morning consultations would be sensible and duly arranged.
By the time Rags was presented an hour later it was evident that we were not facing just another "dustbin tummy" but the makings of a serious problem. Rags was now showing marked excitability with some muscle tremors and a heart rate that was so high I couldn't believe my ears. Rags was quickly admitted. A word with a more experienced colleague put me wise to the problem. Rags was suffering from theobromine or chocolate poisoning. Potentially a lethal situation for a dog as they are much more susceptible to the toxic effects of chocolate compared to people.
The major problem is that there is no antidote for chocolate poisoning and the outcome is mainly governed by the amount of chocolate that was initially eaten. The veterinary surgeon confronted with this scenario can at best attempt to limit the most serious signs of convulsions and circulatory failure and simply has to wait for the dog to metabolise and eliminate the theobromine.
The next three days for Rags consisted of large amounts of intravenous fluids, intensive nursing and an awesome list of drugs to try and stabilise his condition. Despite almost being comatose at one stage he eventually turned the corner and pulled through to make a full recovery. Rags was a very lucky dog as subsequent similar cases have tragically resulted in less happy outcomes.
Chocolate a poison? - Come on!
Well yes. Specifically it's the theobromine in chocolate and cocoa that dogs metabolise much more slowly than humans. The amount of chocolate that will give your average "chocoholic" a buzz will be more than enough to make a small dog ill or at worst kill it.
The Handbook of Poisoning in Cats and Dogs by Alexander Campbell and Michael Chapman suggest the fatal doses of theobromine for dogs is in the range of 90-250mg/kg body weight. The various types of chocolate and cocoa products contain different amounts of theobromine with white chocolate (0.009mg/g) containing the least and cocoa beans containing the highest (up to 43mg/g). Plain chocolate sits about mid way between the two. See the link at the bottom of the page for more details.
To put it into relative terms a small bar of plain chocolate (100-150g) will be enough to kill your average sized Yorkie. A medium sized bar (200g) an average sized Spaniel and a large bar (400g) an average sized Labrador. In some susceptible individuals it may be significantly less!
In case you still feel complacent about the risk, the Veterinary Poisons Information Service (VPIS) in the UK reported that in 1997 they received 50 enquiries about chocolate implicated in poisoning cases and 55 in 1998. Representing over 1% of the total enquiries they received. Several deaths have also been reported. Chocolate has appeared in the VPIS top 20 list of pet poisoning cases since its inception.
Hey Who Ate My Chocolate Bar?
Absorption of theobromine from chocolate and cocoa is slow in the dog compared to their owners. The onset of clinical signs is usually seen within 24 hours but more likely within four hours. Once seen the signs may persist for up to 72 hours because of the relatively slow metabolism of theobromine in the dog.
The common signs first seen following chocolate poisoning include vomiting, abdominal pain, restlessness, excitability, hyperactivity, salivation, increased thirst and a high heart rate.
In more severe cases there may be muscle tremors, convulsions and severe disturbances to the heartbeat that can lead to circulatory failure.
Treatment
There is no antidote. At best, treatment aims to control the severity of the signs until the dog can metabolise and eliminate the theobromine itself.
If chocolate poisoning is discovered and treatment begun within three hours before any overt signs have developed the veterinary surgeon will often empty the stomach by giving a drug to produce vomiting. This may be followed by an adsorbent charcoal mixture into the stomach. This will help stop further absorption of the theobromine and reduce the signs that subsequently develop.
Once the signs of poisoning are manifested then treatment is given depending on the signs seen. Drugs can be given to control sickness, seizures and fluids to prevent dehydration.
In severe cases intensive care may extend over a number of days with no guarantee of the outcome. This level of care will also result in a very considerable cost to the owner both financially and emotionally.
The Take Home Message
Chocolate poisoning is a very real threat to your dog. Don't encourage it to develop a taste for any type of chocolate even the "safe" forms by feeding them as treats. Secure loose chocolates and partially eaten bars. Have a look around, I'm often amazed at the amount of chocolate based goodies lying about when I visit friends' homes. This is particularly important during the various holiday seasons of Christmas and Easter, plus don't forget Valentines Day!
If you suspect your dog has eaten a significant amount of chocolate don't mess around. Get hold of your veterinary surgeon and get the dog seen. After three hours, especially once signs of poisoning have developed you move from a problem that can be relatively easily managed to an emergency that may well kill your pet. Time is of the essence in these cases.
Never forget "death by chocolate" really does happen in dogs!
