For new dog owners, it is vital to know what human foods you can and cannot feed your dog. Some human food is perfectly safe for our pets. However, this article will run through all the foods harmful to dogs and what should be kept out of reach and sight. It is good to know even if you’re not a new dog owner, just to refresh your memory.

Most Dangerous Foods Harmful to Dogs

Some of the different types of food listed below have more extensive effects than others, but all in all, they should always be avoided in order to help keep your dog happy and healthy.


Ingestion of xylitol, found in sugar-free or diabetic foods, causes an insulin release which can cause sugar levels to drop. This is called hypoglycaemia and can be fatal, especially to dogs who are extremely sensitive to the smallest quantities. Xylitol has been linked to acute liver disease and blood clotting disorders in dogs, which can be fatal. Xylitol is mostly found in sugar-free drinks, gum, and sweets and is also in toothpaste, mouthwash and cough drops. Make sure to keep any of these products well away from your puppy.

If you think your dog has ingested xylitol, lookout for symptoms such as vomiting, extreme tiredness, loss of coordination and seizures. These symptoms can develop anywhere from a few minutes to several hours after ingestion.


Found in chocolate theobromine which is a stimulant poisonous to dogs. Symptoms of theobromine poisoning will develop between 4 and 24 hours and include vomiting, hyperactivity, diarrhoea, and seizures. Ingestion of chocolate is likely to affect your dog’s heart, gut, kidneys, and central nervous system. The darker the chocolate is, the more dangerous it is to your puppy. However, it will also depend on the size of your dog and the amount it has consumed.

British Bull Dog


Dogs are far more sensitive and receptive to the effects of caffeine than humans are. You really only need to worry about caffeine consumption if your dog swallows a large amount (one handful) of coffee beans or tea bags; symptoms will be similar to theobromine poisoning.

Allium Species

Anything from the Allium family such as onions, shallots, chives and garlic can cause your dog to suffer from gut irritation and can lead to anaemia and damage to the red blood cells. Onions, in all forms, (raw, dehydrated or cooked) are particularly toxic to dogs. Symptoms do not appear until a few days after ingestion but include weakness, lethargy and dark orange / red-tinged urine.


Alcohol is especially dangerous for dogs. Even the smallest amount of alcohol in beverages or food products can cause side-effects such as decreased coordination, vomiting, diarrhoea, central nervous system depression, breathing difficulties, blood changes, tremors and can be potentially fatal. To treat alcohol poisoning, your dog will be given activated charcoal which will absorb the toxic substance.


Yeast dough causes an accumulation of gas in a dog’s digestive system which can be painful and cause blockages in the intestines or stomach. Never feed your dog raw bread where the yeast has not yet fully risen.

Dog Eating


Although feeding bones to your dog may seem relatively harmless, you must keep an eye on them to ensure they don’t choke on small bone pieces. Avoid giving your dog cooked bones because they’re much more likely to splinter and get stuck in their intestines; bone splinters can pierce a dog’s digestive tract. You must also remember that your dog can not only sustain internal injuries from splinters but chewing on bones can also damage your dog’s teeth. Make sure that if you are going to feed your dogs bones that you monitor the amount you give to them; too much can cause constipation.

Milk & Blue Cheese

Dogs lack the amount of enzyme needed to break down lactose which means that feeding your dog milk-based products can cause sickness and diarrhoea. However, blue cheese is even more dangerous to dogs. They are particularly sensitive to the kinds of blue cheese contain a substance called roquefortine C. This can again cause sickness and diarrhoea if ingested, but can also potentially cause a high temperature, seizures and tremors if an excessive amount has been consumed.

Grapes & Raisins

While grapes and raisins are not dangerous to some dogs, there is a highly toxic substance in grapes and raisins that, to sensitive dogs, can cause kidney failure. Therefore, do not risk finding out whether your dog is sensitive to grapes or not. Symptoms include vomiting, lethargy and diarrhoea and can occur within 12 hours of ingestion. If your dog already has underlying health issues, then they are at a much higher risk of serious illness. It is said that there is no safe dose of raisins or grapes for dogs, so always keep them out of your their reach.

Corn on the cob

A balanced diet is essential for your dog’s health. Make sure to feed your dog a wide variety of foods and health supplements from a number of different food groups, however, corn-on-the-cob does not digest well in a dog’s stomach. If a dog swallows the corn on the cob whole, it can cause intestinal blockages due to its shape and size. If your dog has lost their appetite, is vomiting, failing to produce faeces or suffering from abdominal discomfort, take them straight to the vet.

Macadamia Nuts

If ingested, these specific nuts can cause weakness, vomiting, tremors and depression in your dog within 12 hours and will last approximately 12 to 48 hours. If your dog is showing these symptoms and has been around macadamia nuts recently, take them to the vet and make sure to let your vet know the quantity consumed.


Overall, the foods listed above are the most harmful foods your dog can consume. The foods that have the most damaging effects on dogs are chocolate, allium species, xylitol, grapes and blue cheese. However, this is based on the quantity your pet has consumed and the size of your dog. Always be over cautious and get your dog or puppy seen to if you think they may have consumed any of the specified foods.

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