Chocolate Poisoning in Dogs

Chocolate – it is often listed as one of our many favourite foods, well, at least for some of us that is. However, it contains a particular substance that is toxic to animals. Toxicity or poisoning is usually common in dogs than in cats and other animals. This is because most dogs often have a habit of rapid consumption (now you see it, the next you don’t). So, it is important in this festive season not to over feed your pets and most importantly to keep your chocolates, chocolate-based cakes and goodies safely away from your beloved pets.  

What makes chocolate so toxic to animals?

Chocolate is made from the fruit (beans) of the cacao tree. The ingredient of most concern with chocolate ingestion in small animals is theobromine, which is a methylxanthine alkaloid. Other related compounds are theophylline and caffeine but are present in much smaller amounts in chocolate.

Poisoning with these drugs affect many organ systems in animals of all ages. The most toxic effects of theobromine toxicity is the stimulation of the Central Nervous System (CNS) / the brain. Other effects include cardiovascular stimulation, increased blood pressure (mild), nausea and vomiting. It is important to know that there are many different types of chocolates and some are more toxic than the others.

Baker’s chocolate (unsweetened chocolate) is the most toxic as it carries about 8-10 times the amount of theobromine more than milk chocolate. The amount of theobromine present in semi-sweet chocolate falls between baker’s chocolate and milk chocolate. White chocolate contains theobromine as well, but in such minute amounts that theobromine toxicity is unlikely.

The following is a quick reference guide based on theobromine levels found in two particular types of chocolates:

1. Baker’s chocolate (unsweetened chocolate) = 392 to 450 mg of theobromine per ounce
2. Milk chocolate = 44 to 60 mg of theobromine per ounce Theobromine toxic level in dogs begins at as low as 20mg per kilogram. 

In other words, a 4kg dog would start to show signs of toxicity after ingesting: 11 ounces of milk chocolate, OR 1.25 ounces of baker’s chocolate

Signs of toxicity

In the first 2 to 4 hours after chocolate ingestion, nausea, vomiting and diarrhoea becomes evident. Quite often, chocolate in the vomit can be seen. Gradually, the following signs are commonly seen over the following 6 to 8 hours after chocolate ingestion:

- Hyperactivity
- Nervousness
- Tremors
- Seizures (fits)
- Muscle spasms
- Fast and irregular heart beats
- Excessive urination may be seen due to the diuretic (water clearing) action of theobromine
- Weakness, coma, heart failure and death can occur 12 to 36 hours after chocolate intake at a toxic level

How is chocolate poisoning diagnosed?

Basically, chocolate toxicosis often looks similar to many poisonings such as pesticide and some rodenticide poisonings. If there is a combination of chocolate ingestion, nervousness, vomiting and/or weakness seen, take your dog with a sample of the vomit immediately to the nearest veterinary clinic / hospital. The vomit sample may help in rapid identification of the toxic substance.

How is chocolate toxicity treated?

There is no antidote for chocolate toxicity.
Treatment usually involves:

- Intravenous fluid therapy to treat underlying dehydration caused by vomiting and to induce urination to “flush” theobromine out of the system.

- Inducing vomiting especially if chocolate has been consumed within the previous 2 to 4 hours.

- Stomach tubing and fluids to clear stomach contents followed by activated charcoal treatment to prevent any remaining drug from being absorbed.

- Anti-seizure medications given to control seizure episodes if any.

What can be done while waiting for transportation to the veterinary clinic / hospital?
Stay calm. Panicking will not resolve your problem! If your dog is vomiting, do not try to stop this process for the time being. Allow your pet to clear its stomach contents. If your dog has violent seizures, keep its immediate surroundings well padded with towels so as to prevent head injuries.

Talking to your dog at this stage serves no purpose at all, so just keep its immediate environment as noise-free as possible and transport it to the arranged nearest veterinary clinic / hospital as soon as possible once transport has arrived.

If you happen to find some left over ultracarbon tablets from your previous visit to your general practitioner, you can feed 1-2 ultracarbon tablets to your dog provided it is not seizuring or vomiting.

What is the expected prognosis for chocolate poisoning?
Prognosis is usually good if the chocolate is removed within 2 to 4 hours of ingestion. However, if seizures and serious heart dysfunction is evident, the prognosis for recovery / survival is often very poor.

Contributed by Dr Christopher Tham Jireh Veterinary Clinic Pte Ltd
Image by Jenniferphoon via Flickr