REVIEW article Front. Vet. Sc, 22 March 2016 Sec. Veterinary Pharmacology and Toxicology
Several foods that are perfectly suitable for human consumption can be toxic to dogs and cats. Food-associated poisoning cases involving the accidental ingestion of chocolate and chocolate-based products, Allium spp. (onion, garlic, leek, and chives), macadamia nuts, Vitis vinifera fruits (grapes, raisins, sultanas, and currants), products sweetened with xylitol, alcoholic beverages, and unbaked bread dough have been reported worldwide in the last decade. The poisoning episodes are generally due to lack of public knowledge of the serious health threat to dogs and cats that can be posed by these products. The present review aims to outline the current knowledge of common food items frequently involved in the poisoning of small animals, particularly dogs, and provides an overview of poisoning episodes reported in the literature.
Several foods, while safe for humans, may pose a serious threat to the health of dogs and cats. Food-associated poisoning cases involving the accidental ingestion of chocolate, onions, macadamia nuts, Vitis vinifera fruits (grapes, raisins, sultanas, and currants), xylitol, and ethanol have been recorded worldwide in the last decade (1–3). Foods accounted for 14.8% of hazardous exposure cases reported to the Kansas State Veterinary Diagnostic Laboratory. Chocolate- and cocoa-based products were most commonly involved, followed by products sweetened with xylitol, onions and garlic, grapes and raisins, macadamia nuts, and ethanol (3). In general, the poisoning episodes resulted from a lack of public knowledge of the health hazard to small animals that may be posed by these products. Dogs and cats may be fed harmful foodstuffs by owners unaware of the danger or given the wide occurrence of these products in the home, pets may easily have accidental access to them. Dogs are undiscriminating in their eating habits and will readily ingest potentially harmful foodstuffs, thus being far more commonly affected than cats (4). While some foodstuffs, such as chocolate, have long been known to cause poisoning in dogs and cats, others such as grapes had previously been considered unlikely to cause problems and have emerged as a potential concern only in the last few years (5). As a consequence, cases of significant exposure had been wrongly diagnosed for many years (5). This review aims to outline the current knowledge of common household foods frequently involved in the poisoning of small animals, particularly dogs, and provides an overview of poisoning episodes reported in the literature.
Onion (Allium cepa), garlic (Allium sativum), leek (Allium porrum), and chives (Allium schoenoprasum) are all members of the genus Allium (Amaryllidaceae family). These bulbous plants are strongly aromatic, producing a characteristic odor when crushed, and are commonly used (fresh, cooked, or dehydrated) as ingredients in many dishes. The components responsible for their toxicity are organosulfoxides. Chewing the plant converts organosulfoxides to a complex mixture of sulfur compounds. The primary toxicological mechanism of Allium-derived sulfur compounds is oxidative hemolysis characterized by the development of methemoglobinemia and Heinz body formation in the erythrocytes (6, 7). Cooking, drying, and processing do not eliminate the toxic effect of Allium spp. (7, 8). Dogs and cats are highly susceptible to Allium toxicosis and the ingestion of 5 g/kg of onions by cats and 15–30 g/kg by dogs is enough to cause clinically important hematologic changes (8). In the case of dogs, hereditary high erythrocyte-reduced glutathione and potassium concentrations observed in certain breeds (e.g., Akita, Shiba, and Jindo) lead to greater susceptibility to onion-induced oxidative damage (9). Clinical signs of Allium toxicosis may appear 1 day or several days after consumption depending on the amounts ingested. Common clinical signs initially include vomiting, diarrhea, abdominal pain, loss of appetite, and depression. Due to the developing anemia, pale mucous membranes, weakness, rapid respiratory and heart rates, jaundice, and dark urine (reddish or brown) indicating hemoglobinuria are subsequently observed (7). Several cases of dog and cat poisoning by Allium spp. have been reported in the literature. Poisoning has been reported to occur after the ingestion of Catalan spring onion commonly known as “calcot” (10), baked garlic (11), onion soufflè (12), butter-cooked onions (13), and Chinese steamed dumplings containing Chinese chives (Allium tuberosum) and garlic (14). A case in which a dog was intentionally fed a large quantity of raw onions by the owner has also been reported (15). From 1994 to 2008, 69 cases of canine poisoning and 4 cases of feline poisoning by Allium spp. ingestion (16) were recorded by the Veterinary Poisons Information Service (VPIS). In the case of dogs, vomiting, diarrhea, abdominal pain and, less frequently, anemia, hematuria, and convulsions were reported. Two cases of death occurred and two dogs were euthanized. In the case of cats, gastrointestinal signs, lethargy, and polydipsia occurred in one case, while anemia and icterus were observed in the second case. One cat remained asymptomatic without treatment, and the other cat died from hemorrhage into the pleural and abdominal cavities (16). Recently, hypertension associated with garlic-induced hemolytic anemia has been reported in the case of a dog (11). No specific antidote is available for Allium toxicosis. Inducing vomiting should be considered in asymptomatic dogs and cats, provided there are no complicating factors and not more than 2 h have elapsed since ingestion (8). The administration of activated charcoal is indicated after vomiting has stopped. Once clinical signs have manifested themselves, treatment should consist of supportive care. Severely anemic animals may require a blood transfusion (8).
Ethanol or ethyl alcohol is a two-carbon alcohol found in a variety of products, such as alcoholic beverages, paint and varnish, medication, perfume, mouthwash, certain types of thermometers, and certain forms of antifreeze. It is also used as a disinfectant, a fuel substitute, and if administered intravenously, as a competitive substrate in the treatment of dogs and cats poisoned by ethylene glycol. Ethanol toxicosis in small animals generally occurs as a result of accidental ingestion of alcoholic beverages (17–20). Ethanol intoxication has also been reported in the case of dogs, following ingestion of rotten apples (21), sloe berries used to make sloe gin (22), and uncooked bread and pizza dough (23–25). The latter contains the yeast Saccharomyces cerevisiae, which metabolizes carbohydrate substrates to ethanol and carbon dioxide (26). Once ingested, ethanol is rapidly absorbed from the gastrointestinal tract and crosses the blood–brain barrier (27). The mechanism of action of ethanol is not completely clear. Ethanol is suspected of inhibiting N-methyl-d-aspartate glutamate receptors in brain cells and the related production of cyclic guanosine monophosphate (27). Clinical signs usually develop within an hour of ingestion and include central nervous system (CNS) depression, ataxia, lethargy, sedation, hypothermia, and metabolic acidosis (27). Animals may become comatose and develop severe respiratory depression. A distended and painful abdomen due to excessive gas production may be noted in animals that ingest uncooked bread dough (25). Emesis should be induced with extreme caution and only in cases of very recent ingestion by animals that prove to be asymptomatic (27). Recently, hemodialysis has been shown to be beneficial for the rapid removal of ethanol in patients with severe toxicosis (20). Yohimbine, an alpha 2-adrenergic antagonist which readily crosses the blood–brain barrier, has been recommended as an arousal agent in the treatment of ethanol intoxication (25). In previous case reports, most patients recovered when monitored closely and given supportive care (22, 24, 28). Fatal ethanol intoxication was reported in the case of a dog, following the massive ingestion of rotten apples. The dog developed vomiting, ataxia, tremors, and dehydration, and died 48 h later. However, liver damage secondary to the chronic ingestion of rotten apples (presumed to reflect chronic ethanol toxicity) was suspected as a factor in the death of this dog (21).
Last but not least, fertilizers and weed killers can also do major damage if your pet acquires a taste for them. Keep an eye out while gardening (and after youre done planting, too).
Dont induce vomiting unless directed by a professional. “If youre dealing with something like a cleaning product that can cause burns in the stomach and esophagus, its worse to make them vomit because you can cause more damage,” Dr. Wismer says.
Chocolate gets its own special entry, because when combined with other foods it would probably top the list every single year, Dr. Wismer says. The APCC gets nearly 60 cases related to cocoa every single day! The toxicity depends on the size of animal and the darkness of the chocolate. For a 20-pound dog, it would take 16 ounces of milk chocolate, 9 ounces of dark chocolate, or only 1.5 ounces of baking chocolate to cause seizures.
Its no secret dogs will eat just about anything — helpful when youve dropped some popcorn on the floor, but not so great when your pup finds the Easter chocolate before your kids do. To combat accidental poisonings, the ASPCA Animal Poison Control Center (APCC) analyzed the 213,773 cases it handled last year and found the 10 most common toxins responsible for sickening pets.
If your dog or cat consumes something potentially toxic, always call your vet or local emergency clinic ASAP. “Many times its not only safer for the animal, but its going to be less on your pocketbook to be preemptive,” says Tina Wismer, DVM, DABVT, DABT, Medical Director at the APCC. Expect to answer questions about your animals weight, age, and any existing health conditions or medications as well as what theyve ingested, how much they ate, and how long ago. That information can help determine whether youll need to seek veterinary care or just carefully monitor your pet at home.
Plant species in the Allium genius — such as onions, chives, garlic and leeks — often make dogs and cats sick. These common ingredients contain compounds called organosulfoxides. When the animal chews the plant, the organosulfoxides are converted into a complex mixture of sulfur compounds, which can cause the animals red blood cells to break down. If the dog or cat ingests even just a piece of an onion (specifically, 5 grams of onion per kilogram of body weight for cats, or 15 to 30 grams per kg for dogs), it can cause dangerous changes to their blood.
Ethanol isnt found only in foods and beverages, however. Paint and varnish, medication, perfume, mouthwash and certain types of antifreeze also contain the compound.
Grapes, raisins, sultanas and currants in both raw and cooked forms (including those found in snack bars and baked goods) have been reported to cause kidney failure in dogs. However, not all dogs have the same reactions to these foods, according to the review.
Symptoms of xylitol poisoning may develop within 30 to 60 minutes of ingestion, but they also may occur up to 12 hours later. These symptoms include vomiting and signs of hypoglycemia (low blood sugar), such as lethargy, inability to control movements, collapsing and seizures.
Theobromine and caffeine are also found in other types of products. Poisoning cases have been reported after the ingestion of herbal supplements, garden mulch made of cacao bean shells, caffeine tablets and caffeine-containing bait, according to the review.
13 Common House Plants Poisonous to Dogs and Cats
Our Animal Poison Control Center experts have put together a handy list of the top toxic people foods to avoid feeding your pet. As always, if you suspect your pet has eaten any of the following foods, please note the amount ingested and contact your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435.
Alcohol Alcoholic beverages and food products containing alcohol can cause vomiting, diarrhea, decreased coordination, central nervous system depression, difficulty breathing, tremors, abnormal blood acidity, coma and even death. Under no circumstances should your pet be given any alcohol. If you suspect that your pet has ingested alcohol, contact your veterinarian or the ASPCA Animal Poison Control Center immediately.
Avocado Avocado is primarily a problem for birds, rabbits, donkeys, horses, and ruminants including sheep and goats. The biggest concern is for cardiovascular damage and death in birds and rabbits. Horses, donkeys and ruminants frequently get swollen, edematous head and neck.
Chocolate, Coffee and Caffeine These products all contain substances called methylxanthines, which are found in cacao seeds, the fruit of the plant used to make coffee, and in the nuts of an extract used in some sodas. When ingested by pets, methylxanthines can cause vomiting and diarrhea, panting, excessive thirst and urination, hyperactivity, abnormal heart rhythm, tremors, seizures and even death. Note that darker chocolate is more dangerous than milk chocolate. White chocolate has the lowest level of methylxanthines, while baking chocolate contains the highest.
Citrus The stems, leaves, peels, fruit and seeds of citrus plants contain varying amounts of citric acid, essential oils that can cause irritation and possibly even central nervous system depression if ingested in significant amounts. Small doses, such as eating the fruit, are not likely to present problems beyond minor stomach upset.
Coconut and Coconut Oil When ingested in small amounts, coconut and coconut-based products are not likely to cause serious harm to your pet. The flesh and milk of fresh coconuts do contain oils that may cause stomach upset, loose stools or diarrhea. Because of this, we encourage you to use caution when offering your pets these foods. Coconut water is high in potassium and should not be given to your pet.
Grapes and Raisins Although the toxic substance within grapes and raisins is unknown, these fruits can cause kidney failure. Until more information is known about the toxic substance, it is best to avoid feeding grapes and raisins to dogs.
Macadamia Nuts Macadamia nuts can cause weakness, depression, vomiting, tremors and hyperthermia in dogs. Signs usually appear within 12 hours of ingestion and can last approximately 24 to 48 hours.
Milk and Dairy Because pets do not possess significant amounts of lactase (the enzyme that breaks down lactose in milk), milk and other dairy-based products cause them diarrhea or other digestive upset.
Nuts Nuts, including almonds, pecans, and walnuts, contain high amounts of oils and fats. The fats can cause vomiting and diarrhea, and potentially pancreatitis in pets.
Onions, Garlic, Chives These vegetables and herbs can cause gastrointestinal irritation and could lead to red blood cell damage and anemia. Although cats are more susceptible, dogs are also at risk if a large enough amount is consumed.
Raw/Undercooked Meat, Eggs and Bones Raw meat and raw eggs can contain bacteria such as Salmonella and E. coli that can be harmful to pets and humans. Raw eggs contain an enzyme called avidin that decreases the absorption of biotin (a B vitamin), which can lead to skin and coat problems. Feeding your pet raw bones may seem like a natural and healthy option that might occur if your pet lived in the wild. However, this can be very dangerous for a domestic pet, who might choke on bones, or sustain a grave injury should the bone splinter and become lodged in or puncture your pet’s digestive tract.
Salt and Salty Snack Foods Large amounts of salt can produce excessive thirst and urination, or even sodium ion poisoning in pets. Signs that your pet may have eaten too many salty foods include vomiting, diarrhea, depression, tremors, elevated body temperature, seizures and even death. As such, we encourage you to avoid feeding salt-heavy snacks like potato chips, pretzels, and salted popcorn to your pets.
Xylitol Xylitol is used as a sweetener in many products, including gum, candy, baked goods and toothpaste. It can cause insulin release in most species, which can lead to liver failure. The increase in insulin leads to hypoglycemia (lowered sugar levels). Initial signs of toxicosis include vomiting, lethargy and loss of coordination. Signs can progress to seizures. Elevated liver enzymes and liver failure can be seen within a few days.
Yeast Dough Yeast dough can rise and cause gas to accumulate in your pet’s digestive system. This can be painful and can cause the stomach to bloat, and potentially twist, becoming a life threatening emergency. The yeast produce ethanol as a by-product and a dog ingesting raw bread dough can become drunk (See alcohol).