18 Ingredients to avoid in dog food and reasons to be cautious about them

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ingredients to avoid in dog food

We all love our pets. And what’s not to love? They are cute, charming, funny… and they know it. Who hasn’t had the experience of being at the dinner table with your furry friend looking at you with such puppy eyes begging for what you are eating?

We should resist their looks, and we have to think twice about what we are giving them since they are ingredients to avoid in dog and cat food.

There was always the fact, at least in my grandparents’ household, that the dogs and cats were always eating the leftovers from their humans’ dishes, but we know nowadays that our dog or cat digestive system don’t process well some of the food ingredients we eat.

Here there are some ingredients to avoid in dog food and reasons you should not give them to your dog. This is what can dogs not eat.

1. Onion and Garlic

Normally your pet would avoid eating these ingredients, but if your pet likes to eat everything he or she finds, make sure that it can’t get to these foods.

According to the Pet Poison Helpline, a 24/7 pet poison control centre, plants and vegetables in the onion family, such as garlic, leek, chives, contain Propyl Disulfide. This chemical destroys animal’s red blood cells, causing anaemia, which in severe cases can do serious damage to the internal organs.

The most known symptoms are:

  • Nausea

  • Vomiting

  • Diarrhoea

  • Lethargy

  • Abdominal pain

  • Increased heart rate

If you see any of these symptoms in your pet after eating Onion or garlic, please contact your vet. [1] [2]

2. Corn

Some people believe that giving their dog corn on the cob is actually a safe treat for them. Although the corn itself doesn’t enter the toxic food category itself, feeding your dog with corn in the cob can be actually dangerous for them.

Corn cobs do not fully break down in a dog’s stomach and the size of the cob is often too large to pass through the rest of the gastrointestinal tract.[2]

On the corn itself (without the cob) it is little more than a filler ingredient and a common allergen for plenty of dogs. Corn shouldn’t have a place in high-quality dog foods, especially if it is used as one of the main ingredients. [1]

The most common symptoms of corn cob ingestion are:

  • Sickness

  • Diarrhoea

  • Tiredness

  • Difficulty pooping or producing small amounts of poo

  • Poor appetite

  • Abdominal tenderness or pain

3. Avocados

Avocados have huge benefits for our health, so you should definitely incorporate them into your diet. But although they are very good for humans, we cannot say the same for dogs. They contain a fungicidal toxin called persin. [1]

According to the Pet Poison Helpline, persin is a mild poison for dogs, which if ingested by your pet can provoke the following symptoms: [2]

  • Gastrointestinal problems

  • Trouble breathing

  • Heart issues

It will not kill your dog if ingested, but certain medical conditions could be worsened by avocados, so definitely avoid them.

You can substitute them with other foods that provide similar health benefits but are without persin.

Also, if the dog consumes the pit, it can result in gastrointestinal blockage and cause serious complications.

Additionally, the hard pit presents a choking hazard if ingested. It’s not safe to let your dog eat these parts of the avocado. If you have an avocado tree on your property, make sure your dog does not have access to the fruit. Also if you are eating it, ensure he can not find the pit later on in the trash.

4. Chocolate

We all love chocolate in all shapes and forms, and it even has some good effects reported in humans, like serotonin, which an increase in this elevates our happiness. Unfortunately, it doesn’t work the same way for dogs and cats. [1]

Chocolate contains a chemical called theobromine, which is poisonous to dogs and also to cats. Humans easily metabolize theobromine, but dogs process it much more slowly, allowing it to build up to toxic levels in their system. [2]

The darker kinds of chocolate contain more quantity of theobromine.

No amount of chocolate is safe for your dog or cat, but with large amounts, theobromine can produce the following symptoms:

  • Muscle tremors

  • Seizures

  • Irregular heartbeat

  • Internal bleeding

  • Heart attack.

The onset of theobromine poisoning is usually marked by severe hyperactivity. Be aware that big dogs will get affected slower than small dogs or cats, so it will be toxic much quicker for the later ones.

If you have a small dog that has eaten a box of chocolates, take it to the vet immediately. Do not wait to see if it gets better. Normally the treatment will be to induce vomiting within two hours of the ingestion. In severe cases, symptoms can last up to 72 hours. Early treatment will help your dog recover quicker and lower your costs.

Never give a chocolate chip as a treat for a dog, as it can seriously damage your furry friend.

5. Coffee

Believe it or not, some dogs like coffee! My cat also gets crazy with the smell of a brew and wants desperately to lick the teaspoon. I have even seen some dog owners think it’s cute to allow their dog to finish the last inch of a cold Starbucks coffee.

According to Dr Romero, a veterinary advisor, ”Even for a large dog, it only takes ingesting a small amount to have toxic effects”. [1]

The dose of the caffeine varies depending on the size of your dog. Drinking a splash of coffee is unlikely to contain enough caffeine to irreparably harm your dog, although it might make them sick; however, if your dog were to eat coffee grounds, it could lead to serious caffeine poisoning. Too much caffeine can even be fatal for a dog. [10]

Common symptoms of the coffee ingestion can be:

  • Vomiting

  • Diarrhoea

  • Loss of muscle control

  • Tremors

  • Seizures

  • Collapse

The onset of caffeine poisoning is usually marked by severe hyperactivity. If you are aware that your dog has ingested caffeine in any form, do not hesitate on taking it to the vet.

Be aware that the coffee also contains theobromine, which is also toxic to dogs and cats as stated with chocolate.

When you finish your morning brew, make sure the grains of coffee is out of reach from your pet’s paw. Also no matter how much your furry friend begs, do not let them finish your cold coffee.

6. Bones

Dogs and bones go always like a natural pairing. It is impossible to imagine one without the other.

Although it forms part of the collective imaginary, some bones present a health hazard for your dog, and also for your cat too.

Chewing is a natural dog’s behaviour, and bones are full of minerals that are good for your dog, but you need to be aware of the fact that cooked chicken bones are bad and even dangerous for dogs, as they break and splinter into small, sharp pieces that can cut your dog’s mouth or digestive system.

Broken pieces of bones can cause:

  • Mouth and tongue lacerations

  • Choking

  • Broken teeth

  • Cuts and wounds in the mouth or on the tonsils

  • Vomiting and diarrhoea

  • Severe constipation

  • An intestinal blockage that may require surgery

The safest bet is never to give your furry friend a cooked bone. Even the beef bones can break, causing the above symptoms. In addition to being unsafe, cooked bones are not as healthy as other bones, as most of the minerals and positive properties are stripped off in the boiling process.

In general, raw bones are a lot safer than cooked ones. Although you should consider some bones not to give to your dog. These include:

  • Pork bones, which easily splinter and crack

  • Rib bones of any kind, which are small and likely to crack or get stuck in your dog’s throat

  • Any bone smaller than your dog’s mouth that they may swallow whole

If you would like to feed a bone to your dog, you should consider bones from cow and bison, which are generally safe when used appropriately. You should purchase bones from a butcher with locally sourced meat, store them in the freezer, and thaw them one at a time to give to your dog.

When choosing a raw bone, the general rule is that it has to be equal or slightly bigger than your dogs head, so your dog can chew while reducing the risk of splinting in small chunks that can be swallowed.

A small piece of advice about dog raw bones: they can transmit food-borne illnesses, like salmonella. If you give your dog a raw bone, make sure you throw it out in a couple of hours. [11]

7. Apples

It’s difficult to imagine something that can be good for a human’s health but can be dangerous for your dog or cat. Apples are dangerous for our little furry companions, especially the red ones.

But it’s not the apple itself that is dangerous here. The seeds and core contain a toxic substance called cyanide, which is extremely harmful to animals. It would take quite a few seeds to cause any kind of cyanide poisoning, and if your dog swallows a few, it isn’t likely to cause harm. Even so, it’s not necessary to risk your dog’s health, so remove the seeds before you feed your dog apples.

The main things to watch for, when feeding apples to dogs are seeds and cores, so the rest of it is good if given in moderation.

Apples contain sugar, so serve them carefully. Additionally, too many apples can cause an upset stomach or diarrhoea, even in healthy dogs.

It’s not only the apple seeds that contain cyanide. You should be watching for cherries and apricots.

The first signs of cyanide poisoning are:

  • Vomiting

  • Diarrhoea

  • Dehydration


8. Tomatoes

Ultimately, yes, dogs can eat tomatoes. But if — and only if — they are red tomatoes. If you want to feed your dog tomatoes, you must first understand what the tomato plant is made up of and how its components might harm your dog’s health.

Tomatoes contain solanine and alpha tomatine, two poisonous compounds which are also present in nightshade plants like green potatoes and eggplant. They contain the most solanine in the green parts of the tomato plant: the stems, vines, and leaves.

The tomato itself contains high levels of solanine when it’s young and green. The concentration of solanine rapidly decreases as the tomato ripens. This makes it safe for dogs to eat ripe tomatoes but never green tomatoes.

That’s why, if you have a kitchen garden in your backyard, be careful if your dog is looking for a snack around the tomato plants, especially when they are not ripened yet, as it could be dangerous.

If your dog eats a large quantity of tomatine or from the green parts of the tomato plant, symptoms are:

  • Diarrhoea

  • Vomiting

  • Lethargy

  • Weakness

  • Confusion and loss of coordination

  • Dilated pupils

  • Loss of appetite

  • Hypersalivation (lots of drooling)

Should your dog experience the aforementioned symptoms related to tomato poisoning, take them to the vet as soon as possible. [13] [14]

9. Grapes, Raisins and currants

Recently researchers and veterinarians have found that grapes, raisins and currants can cause kidney failure in dogs. Poison occurs after the ingestion of seeded or seedless variants of grapes, commercial or homegrown, red or green types, organic or non-organic fruit, and grape pressings from wineries.

Also, foods containing grapes, raisins and currants (such as raisin bran cereal, granola mix, trail mix or baked goods) are all potential sources of poison.

Unfortunately, there is not a well established toxic dose for these. It is known that dogs become poisoned after ingesting large doses of fruit. Also, there is significant sensitivity amongst different dogs. Some dogs demonstrate more tolerance to the ingestion and others become poisoned after ingesting just a few grapes or raisins.

Symptoms of grapes, raisin and currant poisoning are:

  • Vomiting, which is generally seen within 24 hours following ingestion.

  • Lack of appetite

  • Lethargy

  • Possibly diarrhoea can be also seen within the next 12-24 hours.

More severe signs are not seen for 24-48 hours after ingestion – often after acute kidney failure has already begun. Signs of acute kidney failure include nausea, lack of appetite, vomiting, uremic breath, diarrhoea, abdominal pain, excessive thirst, and excessive urination.

If you suspect that your dog has eaten grapes, raisins or currants, please call the vet immediately. Don’t wait. [15] [16]

10. Ice cream

Who hasn’t been savouring a refreshing ice cream of your favourite flavour with your furry friend looking at you with those puppy eyes begging for an opportunity to savour that cone? Who hasn’t thought that it would be no harm in sharing a couple of licks with your pup?

Well, you are not really doing your dog a favour. The amount of sugar that goes in it, also almost all adult animals are lactose intolerant, you dog would not enjoy it at all.

Symptoms that they will develop when eating ice cream will be:

  • Diarrhoea

  • Vomiting

  • Gastrointestinal issues

And because of all the amount of sugar in it, they might end up having dental problems
No matter how hot it is and how much do you think they will enjoy it, but don’t give any ice cream to your dog or cat. [17] [18]

11. Soy

Soy is included in a lot of food as the main protein source as it’s cheaper than meats and eggs and is sometimes used as a substitute for certain allergens, like beef, dairy, wheat, chicken and egg.

However, some dog nutrition specialists are saying that Soy might not be entirely safe for your dog, as it can cause:

  • Gas and bloating (GDV – gastric dilation-volvulus) The stomach fills with air and pressure builds, meaning that blood in the hind legs and abdomen can’t reach the heart

  • Kidney stones

  • Thyroid damage

Dog foods that are high in soy have been found to increase the risk of bloating. In recent years, more and more consumers have been demanding soy-free options.

Whilst soy hasn’t been declared unsafe for dogs, it’s important to monitor your dog’s diet. Some dogs might react well to it, but if you notice your dog with some digestion problems, or sluggish, consider changing into a soy-free menu option to be sure. A good alternative is a hemp-based protein. [19]

12. Macadamia nuts

Who doesn’t like macadamia nuts? They are tasty, creamy, healthy, and a great source of protein. Also, they make a great ingredient when baking cookies, especially during the fall.

Although macadamia nuts are healthy for humans, it is not such a good idea for dogs. Your furry friend would only need to eat a small amount to experience a bad health moment.

The symptoms in dogs after eating macadamia nuts can be:

  • Diarrhoea

  • Vomiting

  • Weakness in the back legs

In most cases, these negative effects can be mild, and manageable at home, but in more serious cases, it has to be managed by a professional. Anyway, if you suspect your pup has eaten macadamia nuts you should contact your vet immediately.

Symptoms for a stronger negative reaction might include:

  • Shaking constantly

  • High fever

  • Unable to walk

If you see your dog vomiting experiencing a lack of appetite, stomach pain or a decrease in activity level within three days of eating macadamia nuts, you should contact your vet immediately. [20]

13. Peanut butter

Many people use peanut butter as a reward value for training their dog, for keeping them entertained for a while, or even as a distraction when the humans want to take a nap or attend to other tasks. The truth is dogs love peanut butter!

There is no simple answer to the question of if it is safe for them. Whilst most peanut butter is safe in moderation, be aware that some brands include an ingredient called Xylitol, which is even in small quantities can be fatal. [21]

Xylitol is an artificial sweetener that is often used in food to keep them Sugar-free. Always read the label before giving your pup peanut butter, and never give it to them if Xylitol is in the list of ingredients.

Some dogs shouldn’t be eating peanut butter, even if it doesn’t have Xylitol in it. Those are:

  • Overweight dogs. Peanut butter contains fat so it’s not ideal for pups who are or should be on a diet.

  • Dogs with kidney problems, like peanut butter, contains big amounts of salt, which is not good for this health issue.

  • Dogs who need special diets. If your dog needs a special diet because of allergies, or food sensitivities, you should avoid peanut butter.

As long as peanuts are the only ingredient, your peanut butter-loving dog doesn’t have to forgo it entirely. Alternating the occasional lick of peanut butter with healthy treats will keep them satisfied. Also Look for all-natural, unsalted peanut butter that lists peanuts as the only ingredient. [21]

14. Alcohol

We should never give anything containing alcohol to our dogs, as this substance is very poisonous. But not only alcoholic drinks. Alcohol poisoning occurs when a dog ingests substances containing ethanol (like alcoholic drinks and liquid medications), isopropanol (such as flea sprays that are alcohol-based), and methanol (as in windshield washer antifreeze). Toxicity occurs rapidly as the alcohol is quickly absorbed into the dog’s system.

Dogs that have consumed toxic amounts of alcohol will show symptoms 30 minutes after the ingestion. These could be:

  • Vomiting

  • Disorientation

  • Inebriation

  • Loss of bodily control (ataxia)

  • Diarrhoea

  • Hypersalivation

  • The excitement which changes to depression

  • Difficulty breathing (dyspnea)

  • Loss of consciousness

  • Dehydration

  • Slow heart rate (bradycardia)

  • Seizures

  • Heart rhythm problems

If you suspect that your dog has ingested a product like rubbing alcohol, uncooked bread dough, or cough medicine, or if it is reacting to a shampoo, call your vet immediately. Symptoms can range from mild intoxication to severe.

The good news is that the majority of dogs wouldn’t drink alcohol, as the flavour is repellent for them, but beware holiday stress can cause your pets to act in ways they normally wouldn’t, like table surfing or digging in the trash for leftovers.

So, avoid any dangerous situations for your pet by keeping any risky drinks out of their reach and making your guests aware of the dangers that alcohol, beer, wine and many foods pose for pets. [22] [23]

15. Pizza Dough

Some of us love cooking and making our own food. And who doesn’t love a good homely made from scratch oven-baked pizza? Even if we are not in Italy, it is still delicious. Bad news for our four-legged furry friend. The pizza dough is extremely dangerous for dogs.

Dough rapidly grows after ingestion, which can cause life-threatening stomach distension and blockage. Also, the highest risk comes from the fermentation of the yeast in our dog’s stomach, which can lead to alcohol poisoning.

A common scenario is when we prepare the dough and we leave it unattended over the counter all night so it rises, and we wake up to realise our pup has eaten it and is developing symptoms already. In that case, it is really important to take your dog down to the vet immediately. [24][25][26]

16. Raw meat and fish

Like raw eggs, raw meat and fish can have bacteria that potentially could trigger food poisoning. Also, some fish like salmon, trout, sturgeon, or shad, could transmit a parasite that can cause “fish disease” or “salmon poisoning disease”. [27]

If your dog gets any symptoms from eating raw meat or fish, they would look like:

  • Vomiting

  • Fever

  • Big lymph nodes

If your pet gets any of these symptoms after eating raw fish or meat, take him to the vet immediately.

17. Salt

Unfortunately, our pooches love salt as much as we do. Chips, salty biscuits, pretzels, processed meats, cheese… you name it, they love it!

Salt is bad for dogs if they eat too much of it. For example, rock salt left unattended on the kitchen counter or foods with too much salt on them. If they eat too much salt, they will have to counteract it by making several trips to the water station.

Dogs, as well as humans, need sodium as part of the electrolyte balance, so small amounts are not entirely bad for your dog. Like most living things, dogs need salt to help balance fluids and keep nerves functioning properly. Most dog food you purchase has sodium in it, either naturally occurring from ingredients in the food, or through added salt. So, salt, in moderation, is not bad for your dog. In excess, however, it can lead to serious health complications and even death.

Too much salt can cause problems of

  • Vomiting

  • Diarrhoea

  • Lethargy

  • Swelling or fluid accumulation

  • Excessive thirst and urination

  • Tremors & seizures

Salt poisoning (hypernatremia) is life-threatening. If your dog consumes a good quantity of it, please contact your vet for assistance. You’ll need to know about how much salt was ingested, as well as your dog’s size and weight, and their usual diet. [28] [29]

18. Sugary Foods and Drinks

Dogs have taste buds too. Some people believe their dog’s pallet is weird, but the truth is they like sweets too. They also can suffer from addiction to sugar, just like us.

This explains how the brain works. When we eat or drink sugar, the nucleus accumbens area of the brain releases dopamine, which makes us feel good with ourselves. When sugar is consumed often and in increasing amounts, we reach some tolerance, which means that we need more sugar to produce the same quantity of dopamine. That’s how sugar addiction is explained in both, humans and dogs. Also in cats too.

Unfortunately, like humans, dogs suffer the same negative effects after regular sugar consumption:

  • Diabetes

  • Obesity

  • Dental problems, etc

You need to be aware of the ingredients list of some food brands when it comes to sugar, as some of them will add more to create an addiction to that brand. Sugar also comes in many names and forms.

Some of the most used in dog food are sucrose, caramel and corn syrup. Sorbitol is a sugar alcohol derived from fruits and berries, but it can also be created synthetically. Beet pulp is the by-product of sugar production from sugar beets. Fructose is very sweet and is derived from fruits.

Although honey and molasses have often been said to have medicinal properties, keep in mind they are both still sugars.

Small amounts of naturally occurring sugars, such as those found in the foods that make up your dog’s foods, are not bad. However, added sugars, especially those added to dog foods and treats, are not good for your dog. They can create an addiction and lead to health and dental problems. [30] [

Do you know the ingredients to avoid in dog food? What´s next?

Many dogs would not hesitate to eat anything they can find on the table, including a lot of food they shouldn’t be eating. Because they are snarfing they will eat the most they can, which can be potentially threatening with some of the items on this list.

If you suspect that your pup has eaten any of the items above described, please contact your local vet immediately.

Alternatively, why don’t you have a look at the foods my dog can eat.


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