Let's toast to NOT exposing dogs to potential toxic foods like grapes.
Fri, 11/12/2021 - 4:45pm

Pick Your Poison

Beware of chocolate, onion and grape toxicity in dogs

Holiday season is a time of family gatherings, big meals and many types of foods given as gifts. The toxic potential of chocolate, onions and grapes is well known, but the exact reason why they are poisonous is less clear.

What makes chocolate toxic to dogs?

It is common knowledge that there are many different types of chocolate, including milk, dark, white, unsweetened and cocoa powder, to name a few. In order to understand which types of chocolate are more toxic, we need to understand how chocolate is made.

Cacao pods are the fruit of the tropical cacao tree and contain the bitter seeds that are used to make chocolate. The pods are harvested and split open. The seeds are scooped out, fermented and dried, then shipped to chocolate manufacturers, where the seeds are roasted, ground or pressed to remove the seed oil.

Chocolate liquor is the liquid that results from grinding the cacao seeds. Cocoa butter is the fat that is extracted from the chocolate liquor. Cocoa powder is the solid that remains after the cocoa butter is removed from the chocolate liquor. The powder can be treated with alkali in a process called Dutching, or it can be left alone. Cocoa powder is very low in fat.

Unsweetened, or baking, chocolate is basically straight chocolate liquor containing 50% to 60% cocoa butter. Dark chocolate, also known as semisweet, is chocolate that is 35% chocolate liquor. Milk chocolate is at least 10% chocolate liquor, the rest being milk solids, vanilla or lecithin.

Chocolate liquor is the one containing the problem biochemicals. A higher percentage of chocolate liquor in the product means a darker chocolate, which is more toxic.

The fat and sugar in chocolate can create an upset stomach. If consumed in high enough quantities, pancreatitis can develop. Vomiting, diarrhea and abdominal pain are some of the symptoms. In pancreatitis cases, it is the fat that causes the problem more than the chocolate.

Chocolate is toxic because it contains methylxanthines. The specific methylxanthines are theobromine and caffeine, which have similar stimulant and diuretic effects, with the theobromine effects lasting longer than those of the caffeine. Products that contain a large amount of chocolate liquor will contain a large amount of theobromine, making them more dangerous if your dog consumes them. This makes baking chocolate the worst, followed by semisweet and dark chocolate, then milk chocolate.

Signs of theobromine poisoning include vomiting, diarrhea, hyperactivity, tremors, seizures, rapid heart rate and arrhythmias. Since both theobromine and caffeine are diuretics, dogs may show excessive thirst and urination. If enough is eaten, it can be fatal.

How much chocolate would cause a problem?

Toxic doses of theobromine are 9 milligrams (mgs) per pound of the dog’s weight for mild signs and up to 18 mgs per pound for severe signs. Milk chocolate contains 44 mgs per ounce of theobromine, semisweet chocolate contains 150 mg per ounce, and baking chocolate contains 390 mg per ounce. White chocolate has virtually no theobromine and is only a problem because of its fat content.

These calculations can be confusing. Your veterinarian will need to know the type of chocolate and the approximate amount consumed. The owner of a dog I saw recently for this problem brought the empty bag of chocolate with him. It was easy to determine the low risk of S’mores mix that the dog had chowed down.

It takes nearly four days for the effects of chocolate to work its way out of a dog’s system. If the chocolate was eaten recently, vomiting could be induced and activated charcoal given. Otherwise, hospitalization for intravenous fluid therapy, sedation for the tremors, and medication for seizures or cardiac arrhythmias may be required.

Why are onions and garlic bad to feed to dogs?

Onions and garlic, along with chives and leeks, are often used in cooking to enhance the flavor of our dishes. However, when added to dog meals, they can make our dogs sick. All four species of these herbs belong to the Allium family. This is a large family of plants with approximately 95 species of cultivated or native leeks, chives, garlic, onions, shallots and scallions in North America. This does not include the ornamental varieties.

These plants form bulbs that grow underground and are very aromatic. The green shoots that grow above ground are edible as well, but emit a less intense odor. The domesticated species that are usually the cause of canine toxicity are Allium cepa (onion), Allium porrum (leek), Allium sativa (garlic) and Allium schoenoprasum (chive), with garlic being the most toxic.

Any form, including dried, powdered, liquid, cooked or raw, of these vegetables and herbs is poisonous to your dog. Dried and powdered ingredients, such as minced onions and garlic powder, contain a higher concentration substance on a per weight basis due to the water content being removed. For example, one teaspoon of garlic powder is equivalent to eight cloves of fresh garlic. These forms carry a higher risk of accidental poisoning. Human nutritional supplements, usually garlic, are also toxic if your dog consumes them.

How does the toxin affect the dog?

In most cases, ingestion causes irritation to the digestive tract, resulting in vomiting and diarrhea. Sores in the mouth, drooling, nausea and abdominal pain may occur. The symptoms of poisoning vary depending on the amount eaten.

The potentially deadly part of the Allium species is the oxidizing agent N-propyl disulfide. This compound damages red blood cell membranes. It attacks the cell membrane, making the red blood cells fragile and causes them to burst. Red blood cells carry oxygen throughout the body. When these cells are damaged or destroyed, vital body organs do not receive enough oxygen to function. A low red blood cell count, known as anemia, results in an increased heart rate, elevated respiratory rate with increased effort, weakness, red-colored urine, kidney damage, collapse and eventually death.

How is Allium poisoning treated?

Early treatment will give your dog a better prognosis for recovery. If the ingestion occurred within a few hours, your veterinarian may induce vomiting. I recently used a new product, Clevor, which is an eyedrop that makes your dog vomit. It worked great – fast and smooth without the irritation to the digestive tract caused by hydrogen peroxide.

Once the vomiting is controlled, activated charcoal can be given to reduce the absorption of the toxins from the gastrointestinal tract. Fluids are administered intravenously. Blood work is performed to check for red blood cell destruction. Anemic dogs may require oxygen supplementation or a blood transfusion. Since the destruction of red blood cells may not show up for several days, repeat bloodwork to monitor the red blood cell count and kidney values is typically recommended for days to weeks in these dogs.

What causes grape toxicity in dogs?

Grapes (both seeded and seedless), raisins and currants can all cause serious illness in dogs. Foods containing these fruits, such as raisin-bran cereal, granola, trail mix and baked goods are also potential sources of poison. Grape jellies, grape juice and wine do not seem to have any harmful effects.

It is not known why these fruits are toxic. Many dogs can eat grapes and raisins with no ill effects, while other dogs go into kidney failure after consuming just a few. Vomiting, diarrhea, abdominal pain, dehydration, tremors and lethargy are signs of toxicosis. As the poisoning progresses, the kidneys stop functioning and the dog may not be able to produce urine. The dog’s blood pressure may increase dramatically. Toxins in the blood that are usually filtered out through the kidneys build up and the dog will lapse into a coma. Once the kidneys have shut down and are not producing urine, the prognosis for recovery is poor.

Over the years, there has been speculation that the toxicity may be due to a mycotoxin, which is a toxic substance produced by a fungus or mold. Another theory is that a salicylate drug similar to aspirin may be naturally found in the grape, which results in decreased blood flow to the kidneys.

More recently, it has been proposed that tartaric acid may be the cause. Tartaric acid became suspect when Poison Control consulted on a case involving homemade playdough made with cream of tartar. This kitchen spice contains potassium bitartrate, the potassium salt of tartaric acid. Both of these chemical compounds, tartaric acid and potassium bitartrate, are present in high concentrations in grapes.

A clear dose that causes illness has not been established, but ingestion of as few as four to five grapes was implicated in the death of a 10-pound dog. This is scary enough to have us realize grapes, raisins or currants should not be given to our dogs.

 

 

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