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Avocados -

Avocados are dangerous, partly due to a fungicidal toxin called persin. Only high doses are lethal, but mild symptoms like vomiting and diarrhea can occur from consuming smaller portions.

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Apples -

The flesh of apples is not toxic, but the seeds can be poisonous due to a compound called amygdalin. However, they have to be consumed in large quantities and chewed to be toxic.

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Garlic -

Garlic can be fatal to dogs due to a compound called thiosulfate that damages red blood cells. It takes a lot of garlic to cause toxicity, but some breeds are particularly sensitive.

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Milk and other dairy products -

Even though milk and dairy products have calcium-boosting properties, they can be bad for dogs and contribute to levels of lactose intolerance. This can cause a lot of discomfort for canines.

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Macadamia nuts -

In general, nuts are not good for dogs, especially macadamia nuts. These are ranked as the most toxic, which can lead to vomiting, weakness, hyperthermia, and loss of bodily functions.

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Mustard -

Mustard won't be lethal to dogs in small doses, however, it can be toxic in higher amounts. In fact, due to mustard’s mild toxicity, it's often something that’s suggested by vets as a way to induce vomiting when needed.

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Artificial sweetener (xylitol) -

Xylitol is a sugar alternative found in human foods such as candy and many baked sweets. It’s extremely toxic to dogs, causing rapid insulin release that can put them in a coma within 15 to 20 minutes.

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Chocolate -

Chocolate contains a stimulant called theobromine, which is poisonous to dogs. The amount of theobromine depends on the type of chocolate. It mainly affects the gut, heart, central nervous system, and kidneys.

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Onions -

Onions can be poisonous to dogs due to the thiosulfate they contain. Certain dog breeds are more vulnerable, and their size makes a huge difference.

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Cooked bones -

Giving your dog a raw, uncooked bone to chew on is great, but avoid cooked bones. These can easily splinter and in large quantities cause constipation or perforation, which can be fatal.

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Grapes and raisins -

Grapes and raisins rank among the most serious food threats for dogs. Small amounts can even cause sudden kidney failure, and commonly cause vomiting and diarrhea. 

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Caffeine -

A small amount of caffeine won't do any harm, but if your dog swallows a handful of coffee beans or tea bags then it can pose serious danger.

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Yeast -

If your dog eats unbaked dough, it can be extremely dangerous because the fermenting yeast gets quickly absorbed in the bloodstream, where it produces enough ethanol to cause alcohol poisoning.

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Rhubarb -

Rhubarb can cause kidney failure in dogs due to an antinutrient called oxalic acid. The substance creates crystals in the urinary tract and can cause the kidneys to shut down.

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Nutmeg -

Nutmeg contains a compound called myristicin, which, when ingested by dogs in large quantities, can lead to rapid heart rate, hallucinations, and seizures.

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Currants -

Even though true currants are not toxic, most sold in the United States, called Zante currants, are tiny raisins made from Corinth grapes. These cause the same toxicity as regular grapes and raisins.

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Iron vitamins -

Vitamins containing iron can be toxic for dogs, as they can damage their digestive system wall lining, kidneys, and liver. Prenatal supplements are particularly dangerous, as they tend to have higher amounts of iron than standard vitamins.

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Wild mushrooms -

Grocery store mushrooms are typically safe for dogs, but wild mushrooms can be toxic. If you catch your dog trying to eat them in the wilderness, stop them immediately.

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Citrus oil -

It's typically fine for dogs to eat oranges, but citrus oil, often used medicinally, is not okay. This is because of the insecticidal properties of the oil that can lead to liver failure in dogs.

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Peaches -

The peach flesh itself is fine for dogs to eat, but the pits of peaches contain amygdalin, the same substance found in apple seeds, which is toxic for your pup.

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Leeks -

Leeks contain thiosulfate, the same compound that makes onions and garlic unsafe for dogs. These food types are all part of the allium family.

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Cat food -

Cat food won't poison your dog immediately, but it can lead to pancreatitis and other health complications over time, causing organ damage and even death.

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Black walnuts -

Regular walnuts are safe for dogs to eat, but the less common black walnut can be toxic. These are mainly used in desserts and baked goods, but dogs can find them out in nature.

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Spinach -

Spinach contains a high amount of oxalic acid, a substance known to interfere with dogs’ ability to absorb calcium. This can cause kidney damage if consumed regularly.

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Chives -

Like garlic, leeks, and onions, chives can be poisonous to dogs in large amounts. Toxic doses of chives can cause damage to the red blood cells and lead to anemia.

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Tobacco -

Tobacco isn’t technically a food, but it's something ingested by humans, which can be extremely lethal for dogs if they manage to chew on cigarettes.

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Green tomatoes -

Once tomatoes are ripe, then they're safe for dogs. But green tomatoes or not fully ripe red tomatoes can be toxic for dogs due to a substance called solanine.

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Cherries -

Similarly to peaches, cherries contain amygdalin in their pits, which is toxic to dogs. In addition to the toxic pits, cherry flesh can make their stomach upset.

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Potatoes -

Potatoes are toxic for dogs due to them containing solanine. It blocks a chemical called acetylcholine, which dogs need to transmit nerve impulses. And this can result in issues with the nervous system and intestinal tracts.

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Alcohol -

Small amounts won't necessarily kill most dogs, but severe poisoning and other health issues can occur. Alcohol can cause significant drops in blood pressure and blood sugar, which can lead to seizures and even respiratory failure.

Sources: (Healthline) (Vets Now) (The Farmer's Dog) (JetPet Resort)

See also: Little-known facts about dogs that may surprise you

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