Chocolate Toxicity in Dogs

by Dawn Haas

How many times have you been eating that chocolate chip cookie when you look over and see those sad puppy dog eyes staring at you? You remember hearing that chocolate is toxic to dogs. But what makes chocolate toxic to dogs and why is it that some dogs ingest it and don’t get sick? Here are some facts to clear up some of the confusion surrounding chocolate toxicity in dogs.

Chocolate can indeed be toxic to dogs. In fact, it is one of the 20 most reported poisonings. The ingredient in chocolate that causes the toxicity is theobromine. The minimum toxic level of theobromine is 100-200mg/kg with 250-500mg/kg being the level at which half of the dogs would die as a result of consuming chocolate. So what does that mean as far as how much chocolate is toxic? The level of theobromine varies depending on the type of chocolate. The levels of theobromine are listed below:

Type of Chocolate Theobromine level
Milk Chocolate 60 mg/oz
Baking Chocolate 450 mg/oz
Semi-sweet Chocolate 260 mg/oz
Hot Chocolate 12 mg/oz
White Chocolate 1 mg/oz

Given these levels, 4 oz of milk chocolate contains about 240mg of theobromine. Considering that the average chocolate bar contains 2-3 oz of milk chocolate, it would take 2-3 candy bars to produce toxicity in a 10 lb dog. However, a single ounce of baking chocolate could produce severe toxicity in the same size dog.

So, how does chocolate make dogs sick? Theobromine causes the release of certain substances, norepinephrine and epinephrine, that cause an increase in the dog’s heart rate and can cause arrhythmias. Other signs seen with chocolate toxicity can include increased urination, vomiting, diarrhea or hyperactivity within the first few hours. This can lead to hyperthermia, muscle tremors, seizures, coma and even death.

What should be done if a dog does ingest a toxic amount of chocolate? If it has been less than 2 hours, the dog should be made to vomit. Unfortunately, chocolate tends to form a ball in the stomach and may be difficult to remove. Supportive care should be provided for any other signs the dog is exhibiting.

Though it may not be harmful to the dog in small quantities, it is safer to avoid giving chocolate to dogs in general. As with everything else, it’s better to be safe than sorry.

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Ethylene glycol toxicity

Ethylene glycol is a highly toxic liquid commonly used as antifreeze in car radiators. Other sources include heat-exchange fluids sometimes used in solar collectors and icerink freezing equipment, and some brake and transmission fluids, as well as diethylene glycol used in color film processing.

When the temperature outside begins to drop, not only does it remind us about Christmas but also sets everyone into “winterizing” mood, antifreeze poisoning becomes a common small animal toxicity. As a part of routine vehicle maintenance, we change antifreeze and seldom think how we dispose it. Unfortunately, this poison has a sweet taste and often gets “cleaned up” by our four-legged friends. Poor animals! They have no clue what they are getting into by licking antifreeze spills! Sometimes it takes only 1 or 2 teaspoons of ethylene glycol to be ingested to cause severe illness or even death.

How does antifreeze cause intoxication?

Under the influence of certain metabolic changes, ethylene glycol is metabolized into glycolic acid, which causes severe, sometime irreversible, kidney damage. As a result, the animal becomes unable to eliminate the toxin from the body, which leads to neurological signs.

How do I know that my dog or cat has ingested antifreeze?

Most of the time you don’t, because you haven’t witnessed them drinking it. However, you can easily tell that your pet “isn’t doing right”. Peak blood concentration occurs in 1- 3 hrs after ingestion. At this time, you may see signs of alcohol intoxication: depression, knuckling, vomiting or difficulty standing. As time goes by, the animal’s signs may begin to worsen and become totally uncoordinated, or even start to seizure.

What do I have to do?

It is critical to have your pet checked by a veterinarian as soon as possible! Don’t waste time! There’s medication available to help your pet recover, but it is effective only in early stage of the illness.

But best of all, it is always easier to prevent intoxication than treat it. Let’s make sure that our animals have no opportunity to ingest such a lethal poison by keeping all the containers closed when not in use and cleaning up any spills immediately.

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Tylenol® (Acetaminophen) is Toxic to Cats

Tylenol® helps with our aches and pains, so won’t it help Miss Kitty’s? NO!!! Tylenol’s® active ingredient, acetaminophen, is toxic to cats. It only takes one extra strength tablet to be lethal to Miss Kitty. A toxic dose in cats is as little as 50-100 mg/kg. That means 165 mg, which is found in ½ of a regular strength tablet, may be toxic to a 7 lb. cat. Both humans and cats metabolize acetaminophen in the liver. When it is metabolized, there is a pathway that it follows that produces a metabolite that is toxic. Humans have an enzyme called glutathione that joins with this toxic metabolite that makes it non-toxic. Cats are deficient in this glucuronyl transferase so it causes more toxic metabolites to be produced. So to put it simply, cats are deficient in the enzymes necessary for their liver to break down and clear acetaminophen safely. The toxic compound that is left in cats produces free radicals, which are molecules that damage tissue. The liver, kidneys and red blood cells are tissues frequently damaged in animals with acetaminophen toxicity. The molecule within the red blood cells that carries oxygen, hemoglobin, is converted to a molecule that is called methemoglobin, which cannot carry oxygen. This leads to a lack of oxygen to the body showing signs like rapid respiratory rate, brown or muddy pink gums, and weakness. When the liver is damaged, there are signs of vomiting, jaundice and abdominal pain. Other signs that your cat can show includes: swelling of the face and paws as seen in the picture below, and death. It only takes 10 to 60 minutes after ingestion for there to be peak levels of the drug in the bloodstream after ingestion of regular acetaminophen products, and within 60-120 minutes for extended release products. If you suspect that your cat has ingested any acetaminophen, see your vet immediately. If presented within hours of ingestion, your veterinarian can induce vomiting and administer activated charcoal. They then can administer n-acetylcysteine, a drug that provides another substrate for the toxic metabolite to join with. Prognosis can be good if your veterinarian treats soon after ingestion. So you must present your cat early to your veterinarian if you suspect ingestion. Prognosis is poor if signs of liver damage or decreased oxygen are seen. So if you drop any of your medications, make sure you find them and pick them up. Also don’t treat Miss Kitty’s aches and pains with Tylenol®. One lost pill or one dose could mean your pet’s life.

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Potential household hazards

A few plants here and there can add the finishing touches to a room. Although it may have been ‘just what the room needed’ some of these additions can be dangerous for your four legged family members. This article will hit on a few of the common plants that maybe around the house that could cause some problems.



This is a very common houseplant and can be toxic to dogs and cats. The toxin in this plant causes immediate pain and irritation upon chewing of the leaves or stems. You may see your animal pawing at their face, salivating, or even observe some swelling in the face. Ingesting this toxin usually isn’t life threatening and you can help by rinsing out their mouth. If you notice your pet having breathing difficulties find help immediately.


Easter/Tiger Lily

Although these plants are very beautiful they can cause serious problems for your cat if they decide to take a taste. The toxin in these plants causes rapid and severe kidney damage that could potentially be fatal. Ingestion may cause vomiting, lethargy, and anorexia. If you want to have these plants around put them in a location where the cats can’t get to them -this in itself can be a challenge!



This is another plant commonly used in landscapes as a hedge or standing alone. This plant can be fatal to several species including: dogs, cats, guinea pigs, livestock, and horses. Dogs don’t commonly chew on yews but a 50-pound dog would have to ingest less than 2 ounces to receive a toxic dose. The toxin can cause arrhythmias and fatal heart problems. Signs that you may see include weakness, fainting, vomiting, and diarrhea. Remember yews are also toxic to livestock so be careful where you dump your trimmings after pruning!



These ornamental shrubs aren’t commonly nibbled on but they can cause fatal heart problems in dogs, cats, and pet birds. Signs to watch for are similar to that of the yews and include weakness, fainting, salivation, difficulty breathing, vomiting, and diarrhea.



This common holiday plant has been banned from many cat owner households for fear of deadly harm to their feline friends. This however, is a misconception. Although dogs and cats who decide to chew on these plants may begin to salivate, vomit, or even have some diarrhea, it is not a fatal toxin. So feel free to decorate your home with poinsettias this year!

This is just a small list of some common toxic houseplants. If you suspect your animal has ingested part of a plant call your veterinarian immediately. If your animal is having serious complications, like breathing difficulties, get them to a clinic as soon as possible. Important information for the veterinarian includes: what kind and what part of the plant was eaten (if possible), how much, and how long ago the plant was eaten. A little bit of knowledge about the plants around us has the potential to prevent a fatal disaster.

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Rodenticide Poisoning: How to Protect Your Pet

In the fall, it’s not uncommon for even the best kept house to acquire an unwanted rodent visitor coming in from the cold. Many homeowners find that rodenticide is an easy solution to the problem. However, dogs and cats often find these morsels as tasty as the rodents do. Rodenticides kill by not allowing activation of clotting factors in the blood, causing the mouse or rat to bleed internally. This action is not specific to rodents, but happens in any animal that ingests the bait. Therefore preventing pets from encountering rodenticide is very important. If you feel you must use rodenticide, place it in areas of the house that dogs and cats do not have access to, like the attic or basement. Be careful when putting bait behind the stove or under furniture, cats can squeeze themselves into remarkably small spaces. Finally if your dogs or cats are allowed outside, check to see if neighbors are baiting their sheds or barns.

Signs of rodenticide exposure can occur anywhere from one day to one week after ingestion. Signs include not eating, lameness, difficulty breathing, excessive bruising, and bleeding from body openings. If you suspect that your pet has ingested rodenticide, call your veterinarian immediately. It is extremely helpful if you can bring the package from the rodenticide used as there are several different kinds. The prognosis for a poisoned pet can vary greatly depending on the amount ingested and the amount of time before treatment begins. The faster you call your veterinarian, the better chance your pet has for survival.

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Was That Poisonous?

Has your dog or cat just eaten something poisonous? Or was it safe? If you are unsure, read the product label if it is available. Almost all chemicals poisonous to humans are poisonous to our pets as well. Do not attempt to induce vomiting unless the manufacturer suggests it. If you know that your pet drank antifreeze (ethylene glycol), contact your veterinarian, since this is an immediate emergency. There are several drugs that are safe for humans but deadly to our furry friends. These include ibuprofen (Advil, Motrin), naproxen (Aleve), and acetaminophen (Tylenol). Chocolate can be toxic in high doses (more than 4 ounces of milk chocolate, or 1 ounce of baking chocolate per 10 pounds of dog). Many plants are also toxic; however, contrary to popular belief, the poinsettia is not toxic. If you are in doubt if your animal has ingested a poison, contact your veterinarian, or call 1-888-232-8870 or 1-888-426-4435. This is a “pay” service, but they are very helpful and knowledgeable.

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