Common Foods Dangerous to Dogs and Cats

The following is a list is meant to help pet parents recognize some of the foods that are dangerous to dogs and cats and most commonly implicated with poisoning and adverse effects in pets; however, it is not an exhaustive list. Please consult your pet nutritionist or veterinarian before feeding your pet any food not specifically intended for pet consumption.

IF YOU SUSPECT YOUR PET HAS INGESTED ANY OF THESE SUBSTANCES, CONTACT YOUR VETERINARIAN IMMEDIATELY.

Common foods and substances that are dangerous for dogs and cats include, but are not limited to:

• Chocolate and other cocoa-containing products
• Caffeine
• Onions, chives, leeks and garlic
• Avocado
• Grapes and raisins
• Xylitol
• Alcohol
• Hops
• Raw dough
• Macadamia nuts
• Marijuana

Chocolate and other cocoa-containing products

Chocolate, which is made from cocoa, is a common cause of toxicity in dogs¹. The main toxic agent in cocoa products is theobromine, a methylxanthine that stimulates the central nervous system and causes tachycardia (rapid heart beating), respiratory stress, and hyperactivity.  As summarized in the Merck Veterinary Manual, observable signs of poisoning include vomiting, diarrhea, excessive thirst, and restlessness and usually develop within 6-12 hours of ingestion². Darker chocolate and cocoa powder contain more concentrated amounts of theobromine and will lead to more severe reactions, such as abnormal heart rhythms, tremors, seizures, collapse, and in some cases, death³. Dogs, with their eager-to-eat natures, seem to be more likely to consume cocoa-containing products than cats and other pets², but it is still known to be toxic to many animals so should not be fed to any pets.

Caffeine –is another methylxanthine alkaloid, like theobromine in cacao. The mechanism of toxicity and clinical signs are the same as theobromine³.

Onions, chives, leeks, and garlic

Onions, chives, leeks, and garlic are members of the Allium genus of plants, of which all forms (raw, cooked, dehydrated) are dangerous to dogs and cats⁴. Allium species contain various organosulfur compounds that cause oxidative damage within red blood cells, resulting in hemolytic anemia^5,6. In cases where large amounts of any of these plants are ingested, signs may appear within one day of consumption; however, it is more common for clinical signs to develop after several days⁷.  As summarized by Kovalkovičová et al., first observable signs include vomiting, diarrhea, abdominal pain, loss of appetite, depression, and dehydration, later followed by pale mucous membranes, difficulty or rapid breathing, sluggishness, dark-coloured urine, jaundice, weakness, rapid heart rate³. Even small amounts of these vegetables can pose a threat to your pet; ingestion of onions greater than 0.5% of an animal’s body weight is considered toxic⁸.

 Avocado

Studies of avocado toxicity are well documented in birds, as well as horses, rabbits, guinea pigs, and fish; however, there are only a handful of reports in dogs and no cases have been reported for cats². The toxin persin is present in the fruit, pit, bark, and leaves^9,10. Cases of vomiting and diarrhea have been observed in dogs following avocado ingestion; however, more research is needed to provide conclusive evidence of toxicity. One study of two dogs from separate homes reported suspected toxicity due to avocado ingestion, citing in fluid accumulation in the lungs and chest, leading to difficulty breathing and death due to oxygen deprivation. The two dogs affected also had a history of underlying health conditions¹¹.

Grapes and raisins

Acute renal (kidney) failure following ingestion of the fruits of Vitas vinifera (grapes, raisins, currants, and sultanas) has been reported in many dogs, with some cases even resulting in death^12,13, but much about these cases remains a mystery. The mechanism of toxicity has not been identified, a dose-response relationship has not been established, and furthermore, not all dogs seem to be affected¹⁴. Nonetheless, because of the volume and serious nature of reported cases, all incidences of grape or raisin ingestion by dogs should be considered potentially life-threatening². As summarized by the Merck Veterinary Manual, pets suffering from a negative reaction to grape or raisin ingestion will develop vomiting and/or diarrhea within 6 to 12 hours. They may also exhibit a lack of energy, loss of appetite, abdominal pain, weakness, excessive thirst, and tremors, with kidney failure occurring in severe cases and resulting in death². Two reports of suspected Vitas poisoning in cats and one death of a ferret have also been reported¹⁵.

Xylitol

A sweetener commonly used to replace sugar in products such as chewing gum, breath mints, candies, baked goods, and peanut butter, xylitol can pose a serious threat to dogs. Unlike humans, in dogs, xylitol promotes insulin release resulting in a rapid decline in blood sugar levels^16,17. In more serious cases, liver damage, blood clotting disorders, and even death have been reported¹⁸. As summarized by the Merck Veterinary Manual, signs of low blood sugar can begin in as little as 30 minutes and include sluggishness, loss of motor control, vomiting, and seizures². The dose required to achieve toxicity in dogs is 0.05 g per lb of body weight¹⁹. The average piece of chewing gum or breath mint contains between 0.22 to 1.00 grams of xylitol. Therefore, a 10 lb dog would only have to eat one piece of gum to achieve a potentially toxic dose²⁰. There are no studies in the current literature of cats presenting xylitol toxicity. 

 Alcohol

All alcohols have damaging effects on the central nervous system of dogs and cats²¹. One of the most common household alcohols is ethanol, which is present in many commonly found foods and substances including alcoholic beverages, rotting fruit, and even raw dough²². While some pets accidentally find their way into sources of alcohol, like the case of a dog eating rotting apples from the backyard²³, cases of owners intentionally giving their pets alcohol have also been documented³. As described by the Merck Veterinary Manual, observable signs of alcohol poisoning include vomiting, diarrhea, difficulty breathing, excessive thirst, disorientation, and incoordination, and may result in liver failure, coma, and death²¹.

Hops

In addition to alcohol poisoning, beer specifically, presents an added threat – hops. Hops are flowers often used in the brewing process that impart compounds that are dangerous to dogs²⁴, as well as presenting a threat if the hops themselves are consumed; so beware if you’re a home brewer²². As described by Cortinovis and Caloni, within hours of consumption, pets may exhibit signs such as hyperthermia (high temperature), anxiety, rapid heartbeat, rapid breathing or panting, vomiting, abdominal pain, dark urine, and seizures, and risk of death is high²².

Raw dough

Raw dough presents another dual-risk to animals as the warm, moist environment provided by the stomach provides good conditions for the yeast, Saccharomyces cerevisiae that causes dough to rise to do so in the stomach which leads to the production of ethanol and carbon dioxide³. In addition to the ethanol poisoning this may result in, carbon dioxide and the expansion of the dough can cause gas, bloating, blockage of the digestive tract, and potentially stomach rupture²⁵.

Macadamia nuts

Like grapes and raisins, many cases of poor reactions following ingestion of macadamia nuts have been reported in dogs; however, the mechanisms of toxicity have not been identified²². As described in the Merck Veterinary Manual, signs of toxicosis following macadamia nut ingestion often arise within 12 hours and include weakness, depression, vomiting, loss of motor control, tremors, and hyperthermia (high temperature). These usually resolve within 12-48 hours and no fatalities have been reported to date²⁶.

Marijuana

With the recent legalization of marijuana in Canada and parts of the USA, the reports of marijuana toxicity in pets have greatly increased²⁷. The majority of these cases feature dogs; however, there are also reports of adverse effects in cats^28,29. While marijuana ingestion is rarely lethal, many cases involve the consumption of marijuana in combination with chocolate or xylitol in the form of a baked good, resulting in more severe signs³⁰.As reported by Janczyk et al. signs of marijuana intoxication may include head bobbing, vocalization, loss of appetite, depression, drowsiness, disorientation, loss of motor control, rapid heartbeat, tremors, urinary incontinence, hypothermia (low temperature), seizures and, rarely, coma. Signs may persist for up to 96 hours following exposure³¹.

References

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• 2.          Gwaltney-Brant, S. M. Food hazards. Merck Veterinary Manual (2020). Available at: https://www.merckvetmanual.com/special-pet-topics/poisoning/food-hazards. (Accessed: 9th September 2021)
• 3.          Kovalkovičová, N., Řutiaková, I., Pistl, J. & Šutiak, V. Some food toxic for pets. Interdiscip. Toxicol. 2, 169–176 (2009).
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• 7.          Harvey, J. W. & Rackear, D. Experimental onion-induced hemolytic anemia in dogs. Vet. Pathol. 22, 387–392 (1985).
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• 9.          Oelrichs, P. B. et al. Isolation and identification of a compound from avocado (Persea americana) leaves which causes necrosis of the acinar epithelium of the lactating mammary gland and the myocardium. Nat. Toxins 3, 344–349 (1995).
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• 12.        Eubig, P. A. et al. Acute renal failure in dogs after the ingestion of grapes or raisins: a retrospective evaluation of 43 dogs (1992-2002). J. Vet. Intern. Med. 19, 663–674 (2005).
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• 17.        Dunayer, E. K. Hypoglycemia following canine ingestion of xylitol-containing gum. Vet. Hum. Toxicol. 46, 87–88 (2004).
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• 19.        Piscitelli, C. M., Dunayer, E. K. & Aumann, M. Xylitol toxicity in dogs. Compend. Contin. Educ. Vet. 32, 3–6 (2010).
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• 21.        Gwaltney-Brant, S. M. Household hazards: alcohols. Merck Veterinary Manual (2013). Available at: https://www.merckvetmanual.com/toxicology/household-hazards/alcohols. (Accessed: 22nd September 2021)
• 22.        Cortinovis, C. & Caloni, F. Household food items toxic to dogs and cats. Front. Vet. Sci. 3, 1–7 (2016).
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• 24.        Choi, K. et al. Mechanistic toxicity assessment of hexahydroisohumulone in canine hepatocytes, renal proximal tubules, bone marrow-derived mesenchymal stem cells, and enterocyte-like cells. Int. J. Vet. Heal. Sci. Res. 4, 88–103 (2016).
• 25.        Means, C. Bread dough toxicosis in dogs. J. Vet. Emerg. Crit. Care 13, 39–41 (2003).
• 26.        Gwaltney-Brant, S. M. Macadamia nut toxicosis in dogs. Merck Veterinary Manual (2021). Available at: https://www.merckvetmanual.com/toxicology/food-hazards/macadamia-nut-toxicosis-in-dogs. (Accessed: 22nd September 2021)
• 27.        Stillabower, A. Marijuana toxicity in pets. Pet Poison Helpline (2019). Available at: https://www.petpoisonhelpline.com/pet-safety-tips/marijuana-toxicity-pets/. (Accessed: 23rd September 2021)
• 28.        Janeczek, A., Zawadzki, M., Szpot, P. & Niedzwiedz, A. Marijuana intoxication in a cat. Acta Vet. Scand. 60, 1–4 (2018).
• 29.        Kulpa, J. E., Paulionis, L. J., Eglit, G. M. L. & Vaughn, D. M. Safety and tolerability of escalating cannabinoid doses in healthy cats. J. Feline Med. Surg. (2021). doi:10.1177/1098612X211004215
• 30.        Brutlag, A. & Hommerding, H. Toxicology of marijuana, synthetic cannabinoids, and cannabidiol in dogs and cats. Vet. Clin. North Am. – Small Anim. Pract. 48, 1087–1102 (2018).
• 31.        Janczyk, P., Donaldson, C. W. & Gwaltney, S. Two hundred and thirteen cases of marijuana toxicoses in dogs. Vet. Hum. Toxicol. 46, 19–21 (2004).