Toxic Foods for Dogs: Are they truly toxic?

When you ‘Google’ “Toxic Foods for Dogs” and quickly read through the various articles, you might inadvertently believe that a food is toxic, when it truly is not. While the authors go on to explain if a particular food is or is not toxic, you still may have the embedded thought that it is toxic.

What is the true definition of toxic? Toxic means containing material or being poisonous, especially when capable of causing death or serious debilitation.

In terms of the strict definition of toxic food, we think of a chemical or something else in the food that can actually affect the health or lifelong well-being of a dog and possibly lead to death.

When we read further, we noticed four prevalent categories:

  • toxic to dogs in particular
  • not so much toxic to dogs, but potentially lethal
  • excessive consumption
  • choking hazard

Within these guidelines, we chose to put the foods into one or more of these buckets.

In the first part of this Blog series, we discuss the actual toxic foods.

Please know that with all of the foods detailed throughout the series, we encourage everyone to know where your local emergency veterinary clinic is and to have the number programmed into your phone.

Grapes and Raisins

Grapes and raisins can cause acute and severe kidney failure in dogs. Veterinarians do not know the exact toxin in these fruits that cause toxicity in companion dogs.

Signs of grape and raisin poisoning:

  • Acute renal (kidney) failure
  • Diarrhea
  • Abdominal pain
  • Loss of appetite
  • Vomiting


Zante currants are commonly sold in the United States. They are actually raisins that can also cause acute kidney failure in dogs just like grapes and raisins.

Black, red and white currants are truly currants and are different than Zante currants. They are not considered toxic to dogs. Of course, overconsumption could lead to stomach upset if too many are eaten.

Seeds and Pits of Certain Fruits

At Hemopet, we encourage our clients to treat their companion dogs with small amounts of fruits like apricots, apples and peaches. When we say that, we mean the portions that we humans will eat.

Peach pits, apricot seeds (kernels), plum pits, cherry pits and apple seeds contain cyanide, which is truly a toxin.

The signs of cyanide poisoning:

  • Bright red gums
  • Death
  • Difficulty breathing
  • Dilated pupils
  • Inadequate oxygen levels
  • Shock

If you have a cherry or apricot tree in your yard, please keep your companion dog away from it due to the cyanide in the leaves and stems. Note that avocadoes leaves, stem and fruit contain the toxin, persin, so large amounts are dangerous for dogs and cats, and can be lethal to farm animals. We discuss avocadoes further again in Part III of this Blog series.


Everyone knows dogs should not have chocolate. But why exactly?

Chocolate contains two methylxanthine chemicals: theobromine and caffeine. While theobromine is higher in chocolate than caffeine, it is best for veterinarians to account for the total amount of methylxanthines present.

The chemical concentration varies between each type of chocolate. For instance, unsweetened baker’s chocolate has 16 mg/g of methylxanthines, whereas milk chocolate has 2.3 mg/g. The higher the concentration, the more the toxic chocolate is for dogs.

No matter what, we suggest calling your veterinarian or the emergency veterinarian in your area to find out if you should bring your dog in for evaluation and treatment. Please note your companion dog’s weight, as well as the type and amount of chocolate eaten. You can also call the national Animal Poison Control Helpline (888-428-4435, free of charge; 24/7).

Signs of chocolate toxicity:

  • Abdominal pain
  • Central nervous system dysfunction
  • Death
  • Diarrhea
  • Hyperactivity
  • Hypertension (elevated blood pressure)
  • Hyperthermia (elevated body temperature)
  • Increased thirst
  • Irregular heart function – elevated heart rate and abnormal heart rhythms
  • Muscle tremors
  • Restlessness
  • Seizures
  • Tremors
  • Vomiting


Think about it, caffeine is present in more than just coffee, tea and soda. It’s also in the surge of energy drinks and supplements. If your dog just licks your coffee once or twice, he will probably be ok. The bigger concern is coffee grounds, beans and supplements.

Signs of caffeine toxicity:

  • Abnormal heart rhythm
  • Collapse
  • Death
  • Elevated blood pressure (hypertension)
  • Elevated body temperature (hypothermia)
  • Elevated heart rate
  • Hyperactivity
  • Restlessness
  • Seizures
  • Tremors
  • Vomiting


Similar to grapes, macadamia nuts are poisonous to dogs but the exact toxic substance causing the issue is unknown.

Remember this: one nut per kilogram of body weight can induce signs of macadamia nut poisoning.

A macadamia nut weighs between 2.36 and 2.83 grams. According to Merck Veterinary Manual, dogs have shown signs after ingesting 2.4 grams of nuts/kg body weight. If you have a 20 pound dog, he is approximately 9 kilograms. After ingesting 9 macadamia nuts, he may start to show symptoms.

Signs of macadamia nut toxicity:

  • Diarrhea
  • Disruption of nerve and muscle function
  • Increased body temperature
  • Joint stiffness
  • Lethargy
  • Nausea
  • Pancreatitis due to high fat content
  • Paralysis
  • Tremors
  • Vomiting
  • Weakness


When mushrooms are mentioned, this is where confusion generally starts because companion dogs can benefit from the healing effects of medicinal mushrooms.

Let’s look at the big picture of mushrooms:

  • Mushrooms can be edible, medicinal, psychoactive (hallucinogenic), or toxic.
  • There are at least 14,000 known mushroom species around the world. It is estimated the known species are only one-tenth of the total number of species.
  • Accurate mushroom identification is difficult.

When you are out hiking with your companion dog, please make sure he stays away from mushrooms growing out of the ground.

Signs of mushroom toxicity:

  • Aggression
  • Anorexia
  • Ataxia
  • Death
  • Diarrhea
  • Disorientation
  • Kidney failure
  • Liver dysfunction
  • Seizures
  • Tremors
  • Vision problems
  • Vomiting

Some mushroom toxins will affect dogs within 15-30 minutes of ingestion, but others will not produce signs for up to 24 hours.

Onions and Garlic

All types of onions from red to leeks as well as garlic are members of allium family and can cause hemolytic anemia in dogs. Years ago a published clinical case from rural Alaska involved a Yorkshire Terrier that ate a slice of quiche containing onions alongside his pet parent; he had to be rushed by plane to an ER clinic for treatment of hemolytic anemia. Note that all Japanese breeds such as the Shiba Inu and Akita are particularly sensitive to onion poisoning as they have a different type of sodium/potassium pump across their red blood cell membranes.

Onions should be avoided in dogs, but garlic is safe when fed in moderation.

Signs of allium poisoning:

  • Abdominal pain
  • Collapse
  • Diarrhea
  • Drooling
  • Exercise intolerance
  • Hemolytic anemia
  • Increased heart rate
  • Increased respiratory rate
  • Lethargy
  • Nausea
  • Oral irritation
  • Pale gums
  • Vomiting
  • Weakness


Xylitol is a natural, sugar-free sweetener that is in thousands of everyday packaged foods like gum and personal items like toothpaste. The list is truly exhaustive. For dogs, hypoglycemia and/or liver failure can occur.

Hypoglycemia – low blood sugar – can develop within 30 minutes of ingestion or be delayed up to 18 hours due to the type of food or personal item.

Signs of hypoglycemia:

  • Ataxia
  • Coma
  • Depression
  • Hypokalemia
  • Seizures
  • Vomiting
  • Weakness

When it comes to liver failure, you may not notice it until a day or two after xylitol ingestion. If you do suspect that your companion dog got into a product containing xylitol, it is best to take him to an emergency veterinarian because an increase in liver enzymes can be detected between 8-12 hours after ingestion.

Signs of liver failure:

  • Incoordination
  • Jaundice
  • Lethargy
  • Seizures
  • Vomiting


Dodds, Jean. “Medicinal Mushrooms for Pets.” Pet Health Resources Blog, Hemopet, 9 Sept. 2018, https://www.hemopet.org/medicinal-mushrooms-for-pets/.

Gwaltney-Brant, Sharon M. Bread Dough – Toxicology. Merck Veterinary Manual, https://www.merckvetmanual.com/toxicology/food-hazards/bread-dough.

Gwaltney-Brant, Sharon M. Chocolate – Toxicology. Merck Veterinary Manual, https://www.merckvetmanual.com/toxicology/food-hazards/chocolate.

Gwaltney-Brant, Sharon M. Macadamia Nuts – Toxicology. Merck Veterinary Manual, https://www.merckvetmanual.com/toxicology/food-hazards/macadamia-nuts.

Gwaltney-Brant, Sharon M. Xylitol – Toxicology. Merck Veterinary Manual, https://www.merckvetmanual.com/toxicology/food-hazards/xylitol.

Toxic. Merriam-Webster, https://www.merriam-webster.com/dictionary/toxic.

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