Toxic to Dogs, Part 1

[Part 2: House Plants & Flowers coming soon]

There are a lot of foods, plants, and other substances that are toxic to dogs. Some cause a little tummy upset and some can kill. It's really important to know what, and how much, of a substance can cause harm or kill your dog. I'll go over tobacco and caffeine but I'm skipping the obvious substances like bleach, antifreeze, medications, drugs, and alcohol. As you would with toddlers and children, always keep chemicals and substances like that out of reach of your pets. Only give them approved and acceptable medications. Many medications people use are fine for pets such as children's Benadryl and Imodium in appropriate doses. Plastic bottles containing chemicals can be super fun to chew on and some owners let their dogs chew plastic water bottles, which is not something I'm personally a fan of as sharp bits of plastic are easily swallowed and sharp edges can cut their tongue and gums. Some dogs figure out how to open cabinets under the sink that contain cleaning or beauty products or medications that could make them very sick or kill them. If you have an exceptionally curious and nosy dog then consider putting child locks on your cabinets or other areas your dog breaks into that contain dangerous chemicals. Or put the chemicals somewhere else. Manage your environment as needed to prevent any accidents.

Listed under each substance is the effect of the substance, why it causes a reaction, and the typical amount of the substance needed to cause a reaction. The list is alphabetical. If you're looking for something specific hit Ctrl+F on your keyboard (the Find feature) and type in the name of the substance.

The first items are grouped as all sources contain amgydalin (Vitamin B17) which is a cyanide compound.

Please feel free to copy any/all parts to share.

Food, Plants, and Other Substances Toxic to Dogs

Apple (crabapple), alfalfa, apricot, bamboo, beans (fava, garbanzo, lentils, lima, mung), berries (boysenberry, currant, elderberry, gooseberry, huckleberry, loganberry, mulberry, quince, raspberry), buckwheat, cassava, cherry (chokecherry, cherry laurel, pincherry, wild black cherry, etc), cranberry (Swedish/Lignon), elderberry, eucalyptus, flax, nectarine, millet, peach, pear, persimmon, plum, prune, squash, wild blackberry (domestic is ok): Pits, leaves, and other parts of the plant.
Effect: Rapid or difficulty breathing, swollen and irritated mouth and gums, tachycardia, dilated pupils, inadequate oxygen levels, shock, coma, seizures, and death.
Because: Cyanogenic Glycosides called amgydalin (Vitamin B17) which is a cyanide compound. Cyanide inhibits cytochrome oxidase, an enzyme necessary for cellular oxygen transport, preventing appropriate oxygen uptake by cells.All sources listed have medium to high levels.
Dose to cause reaction: Varies by fruit. Some fruits are higher in amygdalin than others. In general it takes large quantities of seeds and most seeds have a hard shell preventing the amygdalin inside to be absorbed. It can take hundreds of seeds of one type of fruit, but only a few pits from another type. Death can occur within 3-4 days. Please see this page for more information about foods containing cyanide, and there are more helpful links at the bottom of that page as well.

Almond, macademia nuts: Contains cyanide, see above.

Avocado: The fruit, pit, and plant itself.
Effect: Difficulty breathing, fluid in chest and around heart. In lactating animals, mastitis occurs within 24 hr of exposure to avocado, accompanied by a 75% decrease in milk production.
Because: Persin, a fatty acid derivative. The Guatemalan variety appears to be the most problematic.
Dose to cause reaction: Purified persin at 60-100 mg/kg causes mastitis in lactating mice and doses >100 mg/kg result in myocardial necrosis. Goats develop severe mastitis when ingesting 20 g of leaves/kg, whereas 30 g of leaves/kg results in cardiac injury. Acute cardiac failure developed in sheep fed avocado leaves at 25 g/kg for 5 days; 5.5 g/kg of leaves fed for 21 days or 2.5 g/kg for 32 days caused chronic cardiac insufficiency. Budgerigars fed 1 g of avocado fruit developed agitation and feather pulling, while 8.7 g of mashed avocado fruit resulted in death within 48 hr.

Broccoli: Florets and stems. Broccoli is NOT technically toxic to dogs.
Effect:  Causes severe gastrointestinal irritation resulting in bad gas.
Because: Isothiocyanate causes the irritation.
Dose to cause reaction: Great than 5% of dog's diet.

Caffeine (Coffee, Tea, Caffeinated or Sugary Drinks (Soda), Certain Medications): The higher the caffeine, the worse it is.
Effect: Similar to the effects of chocolate (see below).
Because: Caffeine is a chemical stimulant that dogs are unable to metabolize effectively. As a result, it is very damaging to the dog's central nervous system.
Dose to cause reaction: As a guideline, the lethal dose is considered to be around 70 mg per 1 lb body weight (150 mg / kg body weight). Instant coffee contains over 60 mg caffeine per teaspoon. The lethal dose of caffeine for a 15 lb dog would be 17 teaspoons of instant coffee. Stronger coffees such as Turkish coffee, percolated coffees, and energy drinks would take much less to become toxic.

Chocolate: The darker the chocolate, the worse it is. Baker's chocolate is most dangerous form, however pure cocoa is extremely deadly as only 3oz can kill a 50 lb dog and only 1oz is needed to kill a 17 lb dog.
Effect: Seizures, coma, hyperactivity,  tachycardia, heart attack, tremors, death. Early signs of include nausea and vomiting, restlessness, diarrhea, muscle tremors, and increased urination or incontinence.
Because:  Theobromine, which is similar to caffeine (see Caffeine abpve).
Dose to cause reaction: Please see The Chocolate Chart provided by National Geographic. This chart allows you to see how much of certain types of chocolate may harm a pet of a certain weight.

Grapes, Raisins: Any type of grape or raisin, both with and without seeds and including winery grapes.
Effect: Kidney failure within 1-3 days including dehydration, abdominal pain, and tremors or seizures. After consumption there may be severe vomiting and diarrhea, excessive thirst and urination, lethargy, weakness, decreased appetite.
Because: Unknown, possibly a mycotoxin (substance produced by fungus or mold).
Dose to cause reaction: 9 oz to 2 lbs of grapes and raisins (between .041 and 1.1 oz/kg of body weight). According to the Merck Veterinary Manual, the estimated toxic dose of grapes is 32 grams of grapes per kilogram of body weight (0.5 ounces per pound) and for raisins it is 11-30 g/kg (0.18 to 0.48 oz/lb).

Milk: Milk-based dairy products. These are NOT technically toxic to dogs.
Effect: Diarrhea, vomiting, gas.
Because: Lactose. Dogs do not possess significant amounts of lactase (the enzyme that breaks down lactose in milk). After weaning, the level of lactase activity falls to about 10% of its peak activity.  Cow and goat milk contains 4.5% to 5% lactose, compared to 3.1% in dog’s milk and 4.2% in cat’s milk. The high level of lactose in cow's milk can overpower a dog or cat's ability to digest it.
Dose to cause reaction: Varies by dog and by product.
-Ice cream has 12g per cup
-Whole milk and skim milk have 11g per cup
-Sour cream has 8g per cup
-Cottage cheese has 6g per cup
-Yogurt has 5g per cup
-American and Swiss cheese have 1g per oz; cheddar cheese has less than 1g per oz.

Mushrooms: Entire plant; not all are toxic. Most common toxic mushrooms are Inocybe spp. and Clitocybe spp. The death cap (Amanita phalloides) is most severe.
Effect: Acute gastric effects, liver and kidney damage leading to jaundice and bleeding disorders, abdominal pain and colic-like symptoms, nausea, salivation and teary eyes, vomiting, small constricted pupils, lethargy, depression. Also hallucinogenic syndrome: Mushrooms that cause this syndrome are known as magic mushrooms, blue legs or liberty caps. Dogs who are hallucinating frequently snap at invisible flies, may be extremely depressed, stagger when walking and become comatose. Muscle tremors and seizures also occur. Dogs who ingest hallucinogenic mushrooms always require rapid decontamination and monitoring by a veterinarian.
Because: Various. Refer to this toxicology brief, "Mushroom poisoning in dogs."
Dose to cause reaction: Varies by mushroom. It is advised to induce vomiting with activated charcoal or hydrogen peroxide. The appropriate dose of hydrogen peroxide is one teaspoon (5 cc or 5mL) per 10 pounds of body weight. Use 3% hydrogen peroxide, not the stronger type used for hair coloring.

Nutmeg: The spice is derived from the seed of a tree. Unknown if tree itself causes reaction but the spice does.
Effect: Tremors, seizures, death, vomiting, abdominal pain, irregular heartbeat. Initial symptoms of arousal often followed by dramatic drowsiness. Hallucinations and delusions possible.
Because: Nutmeg contains myristicin, a compound also found in parsley and dill, which acts to weakly inhibit an enzyme called monoamine oxidase that helps to break down certain brain neurotransmitters. Myristicin can cause personality changes and delusions both directly and through its effects on monoamine oxidase.
Dose to cause reaction:  Unknown. Take into account your dog's size and weight. Just two tablespoons can cause a reaction in a human.

Onion (allium): Leeks, chives, garlic, shallots, scallions, and onions. All 95 species in North America can be toxic to cats and dogs. Reaction can be caused from the plant material, juice, fresh or aged dietary supplements, powdered cooking preparations, and dehydrated material. May be present in baby food.
Effect: Symptoms often develop over several days and may include depression, jaundice, rapid breathing, tachycardia, anemia, weakness, exercise intolerance, cold sensitivity, decreased appetite, abdominal pain, and diarrhea. Red blood cells are destroyed.
Because: Wide variety of organosulfoxides, particularly alk(en)ylcysteine sulfoxides. See this article for a very science-y description.
Dose to cause reaction: As little as 5 g/kg of onions in cats or 15 to 30 g/kg in dogs. Dogs and cats are highly susceptible to onion toxicosis. Toxicosis is consistently noted in animals that ingest more than 0.5% of their body weight in onions at one time. Dogs with heritable high erythrocyte reduced glutathione and potassium concentrations are more susceptible to the hematologic effects of onions. This trait is relatively common in Japanese breeds. Garlic in small amounts may be beneficial.

Rhubarb: Leaves only.
Effects: Excessive salivation, vomiting, nausea, difficulty breathing, burning throat and mouth, stomach pain, diarrhea, seizures and convulsions, kidney damage including kidney stones, stumbling.
Because: Oxalates. Too much oxalic acid in the urine will result in kidney or bladder stones.
Dose to cause reaction: In rats, 375 mg oxalic acid per kg to cause death.  It will only require a fraction of that to cause sickness. Rhubarb leaves are about 0.5% oxalic acid.
Beet tops, cabbage, and spinach leaves also contain oxalates, as do potatoes and peas.

Salt: Sodium chloride. Other than table salt, keep in mind other sources such as play dough, rock salt, and paint balls.
Effect: Vomiting, diarrhea,decreased appetite, lethargy, stumbling, abnormal fluid accumulation within the body, excessive thirst or urination, kidney damage, tremors, seizures, brain swelling, coma, elevated temperature, death.
Because: Sodium ion poisoning caused by the dog being unable to process the salt fast enough.
Dose to cause reaction: About 1 tsp per kg (per 2.2 lbs) body weight. Dose of 2-3g of sodium chloride per kg causes toxicosis. 4g/kg is lethal. (Conversion ratio: 1oz = 28.35g).
-One gram of table salt has 400mg of sodium and 600mg chloride
-One teaspoon of table salt contains over 2,000mg (2g) sodium and 3,000mg (3g) chloride.
 
Tobacco (Nicotine): Chewing tobacco, dipping tobacco (cut, snuff, pouches), cigars (blunts, cigarillos), cigarettes (kreteks), creamy snuff, dokha, gutka, snuff, snus, topical paste, gum and patches, water, pesticide.
Effect: Tremors,weakness, stumbling, depression, hyperactivity, lethargy, irregular or difficulty breathing, salivation, dilated pupils, vomiting, diarrhea, seizures, irregular heart beat or bradycardia or tachycardia.
Because: Nicotine, a poisonous alkaloid derived from the tobacco plant.
Dose to cause reaction: 5mg of nicotine per pound of body weight. In dogs, 10 mg/kg is potentially lethal. In other words, a 10-pound dog would only need to eat about 3 cigarettes in order to show toxic signs. See below:
-One cigarette contains 15 to 25mg of nicotine depending on the brand
--The butt of a cigarette can contain from 4 to 8mg depending on the length of the butt and the content of the original cigarette
-Nicotine patches contain between 8 to 11mg
-Nicotine gum contains approximately 2 to 4mg per piece
-Inhalers contain about 4 mg per puff or 10 mg per cartridge
-Nasal sprays contain approximately 80 to 100mg per bottle or 0.5mg per spray
-A cigar contains approximately 15 to 40mg
-Chewing tobacco contains approximately 6 to 8 mg per gram
-Snuff contains approximately 12 to 17 mg per gram

Yeast dough:
Effect: Drooling, lethargy, stumbling, nausea, vomiting, weakness, lowered body temperature, bloat, death.
Because: Expands and produces gas in the digestive system causing abdominal pain and possible obstruction or rupture of the stomach or intestine, can ferment sugars creating a secondary problem of ethanol (alcohol) poisoning.
Dose to cause reaction: A pingpong sized ball can easily kill a cat or small dog.

Xylitol (artificial sweetener): Sugar-free gum, toothpaste, mouthwash.
Effect: Causes very low blood sugar (hypoglycemia), which can result in vomiting, weakness, collapse, death. In high doses can cause liver failure.
Because: Causes the rapid release of insulin.
Dose to cause reaction: One stick of gum can severely harm a 20 lb dog.