Even though dogs are somewhere between carnivores and omnivores that consume the organic matter of other animals, they can also be classified as opportunistic herbivores.

Dogs have the ability to consume everything from elk antlers to alfalfa, from protein rich beef muscles to nutrient packed blueberries and other foods, thus owners often consider feeding different food items to them, but some human foods dogs can't eat because they're toxic.

Not all human food is bad for dogs.

There are a number of fruits and veggies that dogs enjoy and can safely consume in moderation.

For example, berries like strawberries or cherries, veggies like bell peppers or cucumbers, fruits like bananas or watermelons are not only completely safe for dogs, but even beneficial to their health in many ways.

Worst Human Foods Dogs Cant Eat

There's also a number of bad human foods dogs can't eat and those may not only be an irritant, but likely fatal to dogs.

As more and more food from around the world finds its way into our grocery aisles and into our homes, this “do not feed to dogs list” is growing but there are certain items that are most common, which is why we have some scientific literature on the effects these human foods dogs can't eat have on our pets and what the results are.

In this article, we're taking a look at what research has to tell us about the negative effects of these human foods dogs can't eat and the risks involved. Know and watch out for the symptoms listed below and if you think that something is amiss, contact your veterinarian.

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9 Foods Dogs Cannot Eat and Why (according to studies)

Worst Human Foods Dogs Can't Eat

1. Alcohol

This is clearly a no-brainer.

Alcohol is barely consumable for humans, let alone dogs.

You have undoubtedly seen what alcohol can do to the human mind. Now imagine what it can do to a being a fraction of the size and weight of an average person.

Yet, it still has to be mentioned on a list of human foods dogs can't eat (or drink) because vets see cases of intoxicated dogs.

Unsurprisingly, the effects of alcohol in dogs mimic those of humans. Neurological function is impaired, and significant liver damage is observed.

However, the effects of alcohol are not limited to these two, which we are all already aware of.

There's more:

It has also been observed that the presence of alcohol in a dog's system lowers the calcium content circulating throughout a dog's system (Peng et al. 1972).

It is believed that the presence of alcohol triggers a calcium movement out of the blood and into tissue, such as bone.

This impacts the dog's bone and joint health, followed by a number of related complications.

On a more physiological level, there is evidence to suggest that alcohol intoxication in dogs leads to a higher mortality rate due to respiratory complications when dogs are severely wounded (Gettler et al. 1963).

This is likely due to the fact that alcohol has a depressant effect on the dog's central nervous system, making it difficult for the body to react to such trauma as acute hemorrhaging.

Furthermore, it has been observed that heart function in dogs, particularly the lower ventricles of a canine's heart, can be highly compromised by the consumption of alcohol, leading to a severe risk of heart problems in intoxicated dogs (Cheng et al. 1990).

When it comes to dogs' brains, consuming alcohol doesn't necessarily decrease “grey matter” or “brain cells” per se.

Rather, studies show that it is actually the white matter in a dog's brain that thins, making it more susceptible to damage or glial cell loss (Hansen et al. 1991).

While alcohol doesn't necessarily decrease brain cells in dogs, it does make the entire brain of the dog more fragile than it already is.

Cirrhosis is a known consequence of alcohol consumption in humans, and this statement holds true for canines as well.

Hepatic cirrhosis, among other ailments, has also been shown in dogs that have consumed alcohol (Chaikoff et al. 1948).

As a result, glomerular and tubular damage (damage to tubes of the dog's kidneys) arise along with lesions in dogs.

It doesn't take much for a dog to suffer from alcohol poisoning, either. Alcohol poisoning can cause any of the following symptoms: trouble breathing, liver failure, hypoglycemia, or extremely low blood sugar.

Suffice it to say that alcohol is easily one of the worst human foods dogs can't eat or drink, and you should never give your dog alcohol.

Unfortunate accidents are common because alcohol smells and tastes good and sweet to a dog, and they may go out of the way to seek it out.

That's why if you should ever feel the need to imbibe in libations, then watch your glass to make sure that your pooch keeps its nose and tongue out.

Worst Human Foods Dogs Cant Eat

2. Avocado

Hailing from warm and tropical climates, avocados are often highly regarded for the nutritional and health benefits they bring to humans.

It's a source of healthy fats and tons of nutrients, and avocados are a staple in a growing number of homes.

However, don't be so quick to share that guacamole with your dog because avocados are one of the worst human foods dogs can't eat and take off your table.

Avocados contain a toxin known as persin, which was shown in studies as very toxic to dogs (Buoro et al. 1994).

Persin isn't an issue for humans who can process and pass the substance through their digestive system, but dogs can't do the same, and it ends up accumulating in their system, poisoning them, and causing liver and kidney damage.

It has been observed that including avocados in a dog's diet will lead to considerable damage to the heart and cardiac problems (Kovalkovilcova et al. 2009).

So, while you may consider avocados a delicious, healthy, and essential part of your diet, think twice before giving avocado to your dog.

Sharing these harmful and toxic human foods dogs can't eat with your companion could leave you faced with a situation where you are rushing Fido to a veterinarian to have their stomach pumped.

RELATED: 6 Must-Know Tips for Making Your Own Homemade Dog Food


Worst Human Foods for Dogs

3. Onions and Garlic

It's unlikely to come as a shock to most pet owners that onions and garlic are some of the most well-known human foods dogs can't eat, and they can be completely devastating to a dog's health.

Onions contain a compound called, “N-propyl disulfide”. And garlic contains a compound called thiosulfate. Feeding your dog onions or garlic damages your dog's red blood cells.

The red blood cells are then broken down and ultimately destroyed. The consumption of a large dose of either leads to anemia.

Recently, there has been some talk – particularly from holistic veterinarians – that including some garlic can be beneficial to dogs.

However, we haven't seen any evidence to suggest that garlic is beneficial to dogs, and most of these assumptions are based on the health benefits observed in humans.

To this date, garlic has been shown again and again (Lee, et al. 2000) as toxic and one of the worst human foods dogs can't eat and should never come even close to.

A number of health problems have been observed after feeding raw garlic or baked garlic to dogs (Kang et al. 2009), including hypertension.

Similar risks have been associated with feeding onions to dogs as well.

When it comes to onions, there have been limited studies (Briggs et al. 2001) that suggest that onions may potentially benefit dog health; however, there's no way for dogs to consume onions without experiencing side effects.

So, the fact that a potential adverse effect even exists is enough to merit the omission of onion from a dog's diet altogether.

MUST READ: 32 Dog Food and Feeding Myths You Need to Stop Believing

Worst Human Foods for Dogs

4. Coffee, Tea and Caffeine Products

Morning beverages are usually a godsend for people who need a pick-me-up before they get started with their day. Dogs, being creatures of the present, do not need such things. In fact, caffeinated products are some of the worst human foods dogs can't eat or drink, and giving them anything containing caffeine would be a death sentence.

In large enough quantities, caffeine is lethal to dogs. Much like in humans, caffeinated beverages (which include energy drinks like Red Bull) have the ability to cause arrhythmias, heart palpitations, and tachycardia in dogs, according to studies (Mehta et al. 1997).

One study observed (Warszawski et al. 1977) that particularly susceptible to the fatal effects of caffeine are infant dogs and small breeds due to their size and how much caffeine their body can handle. It's also due to small and infant dogs having lower blood volume. Metabolism plummets while renal excretion skyrockets (Warszawski et al. 1982) when pups consume caffeine.

Remember that, similar to garlic toxicity in dogs, there is no antidote to caffeine poisoning for dogs. Studies show (Tawde et al. 2012) that caffeine toxicity in dogs is also very difficult to notice, confirm, and treat; therefore, place any caffeine products on your list of human foods dogs can't eat or drink, and watch out for those Espresso spills.


Worst Human Foods for Dogs

5. Grapes and Raisins

What begins as a sweet, delicious treat for you, the human, can end up turning your dog into one very sick puppy. While most people already know, it's important to stress the dangers and toxicity of grapes and raisins as some of the worst human foods dogs can't eat.

When it comes to feeding grapes or raisins to dogs, kidney failure is the most commonly observed problem (Eubig et al. 2005). The exact reason why dogs experience renal injury remains unclear to this day; however, enough evidence exists to solidify the link between the two.

After the dog ingests raisins or grapes, kidney failure doesn't happen right away. Dogs will typically exhibit bouts of lethargy, vomiting, anorexia, and diarrhea beforehand. The dangers apply to all types of grape products: dried, juice, and everything else.

The dried raisin, in general, has been shown to have a more toxic effect (Stanley et al. 2008). One may infer that this may be due to the fact that whatever toxin is involved would be more concentrated in the raisin, which is essentially a dried grape.

RELATED: 4 Most Dangerous Ingredients in Dog Foods (According to Science)

Worst Human Foods for Dogs

6. Macadamia Nuts

Mention macadamia nuts and pictures of freshly baked cookies or trees gently swaying in the Hawaiian breeze comes into mind. But beware, do not let your dog eat macadamia nuts.

What most people don't know is what these nuts can do to the insides of their dogs and how some of these human foods dogs can't eat are very dangerous.

The consumption of macadamia nuts by dogs can be fatal theoretically when consumed in large amounts, but no deaths have been reported as of yet (Mahdi et al., 2013). The most likely outcome of a dog eating macadamia nuts is severe illness.

The dog is essentially poisoned when they ingest a macadamia nut (Hansen et al. 2000). They will exhibit symptoms such as involuntary muscle contractions and shakes, fatigue, paralysis, vomiting, elevated temperatures, and a spike in heart rate.

A subtler yet equally concerning symptom of macadamia nut toxicity in dogs is the development of joint pain and recumbency (inability for the dog to stand or remain erect for stretches of time).

It seems that macadamia nuts target and affect the limbic system of canines (McKenzie, 2007) and any prolonged changes in a dog's posture (asides those inflicted by aging) should be a clear sign that the dog should visit the veterinarian as soon as possible.

SIMILAR: 15 Best Sensitive Stomach Dog Foods for Upset Stomachs

Worst Human Foods for Dogs

7. Chocolate

Perhaps the most commonly known among human foods dogs can't eat, chocolate has a great potential to kill a dog.

This isn't mentioned often for posterity or as a scare tactic. Chocolate is considered deadly for dogs and should be avoided like the plague.

The compound known as theobromine in chocolate is well-known as a real killer of dogs (Strachan et al. 1994).

A mere lick of chocolate, especially darker chocolates untainted by the addition of milk, can send a dog spiraling through bouts of thirst, vomiting, diarrhea, arrhythmia, muscle tremors, seizures, and then death.

While other species have been known to react negatively to chocolate as well (Miller et al. 1984), it seems that dogs are most susceptible. Your dog eating chocolate when you are not around is probably the most common situation – dogs love the taste and smell of chocolate.

The biggest problem is not only that a dog has eaten a toxic substance, but also because you do not know how much was consumed nor how much time has elapsed since consumption, which is one of the most important factors for assessment (Finlay, 2005).

The 7 Worst Human Foods Dogs Can't Eat

Fortunately, and unlike with garlic or caffeine, there are treatments and protocols (Ghazaleh, et al. 2008; PDF) that exist for treating dogs with chocolate poisoning. Since dogs that consume chocolate exhibit behaviors that effectively eliminate fluids from their body, it is essential to replace those liquids, making rehydration a first priority in case of chocolate poisoning in dogs.

Again, unlike with some other bad human foods dogs can't eat, there's also medication you can use.

Atropine sulfate and dexamethasone ensure that the dog's system receives a significant boost of energy to fight off the illness, while an assortment of other drugs (to be prescribed on a case-by-case basis) helps them recover to the point where their own systems can take over, according to several experiments (Stidworthy et al. 1994).

8. Raw Yeast Dough

Do not feed your dog this ingredient.

Unlike us, a dog's stomach is small. There are a few things that can happen when a dog eats raw yeast dough:

  1. Upset stomach
  2. Alcohol poisoning from fermentation in their stomach
  3. Yeast dough can stretch in the dog's stomach and expand to the extent that your dog is having severe pain.

9. Salty foods

Dog's cannot eat salty foods. You may think a little bit never hurt nobody, but quite the contrary.

Your dog is much smaller than you, so a little bit of salt to us is a big deal to them.

Feeding your dog too much salt can cause dehydration because it causes they body to pull water from other sources in the body like their cells. Typically, a quick fix is just drink more water, but a dog doesn't know this and it can happen quick.

Your dog can also suffer from sodium ion poisoning.

Too much salt causes not enough moisture in the muscles which can cause them to shrivel, and stiffen up.

This rapid dehydration can lead to your dog having a convulsive episode, going into a coma, or worse, death.

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Mary has a Bachelor of Science in Biology and Neuroscience, and has been specializing in animal science writing for over ten years. She's very experienced in scientific reports, data analysis and science-based research, and obsessed with accurate information.