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Dangers For Dogs



Dogs love the flavour of chocolate, but chocolate in sufficient doses is lethally toxic to dogs (and horses and possibly cats). Chocolate contains theobromine, a chemical stimulant that, together with caffeine and theophylline, belongs to the group of methylxanthine alkaloids. Dogs are unable to metabolise theobromine effectively. If they eat chocolate, the theobromine can remain in their blood streams for up to 20 hours, and these animals may experience fast heart rate, hallucinations, severe diarrhoea, epileptic seizures, heart attacks, internal bleeding, and eventually death. A chocolate bar can be sufficient to make a small dog extremely ill or even kill it. Approximately thirty grams of baking chocolate per kilogram (1/2 ounce per pound) of body weight is enough to be poisonous. In case of accidental intake of chocolate by especially a smaller dog, contact a veterinarian or animal poison control immediately; it is commonly recommended to induce vomiting within two hours of ingestion. Large breeds are less susceptible to chocolate poisoning, but still are far less tolerant of the substance than humans are.

If you wish to give your dog chocolate treats, buy specially made dog chocolate (with the theobromine removed) from your local pet shop.




Onions contain thiosulfate which causes haemolytic anaemia in dogs (and cats). Thiosulfate levels are not affected by cooking or processing.  Small puppies have died of haemolytic anaemia after being fed baby food containing onion powder.  Occasional exposure to small amounts is usually not a problem, but continuous exposure to even small amounts can be a serious threat. Also garlic contains thiosulfate, even if to a significantly lesser extent, and it is also known to cause diarrhoea and vomiting. Anyway small doses of garlic 5-6 times per week can improve dog health, since garlic is a natural anti-microbial and helps to prevent heart disease. It is stated that garlic have also repellent effects on fleas and ticks, especially in combination with brewer's or nutritional yeast.


Macadamia Nuts


Macadamia nuts can cause stiffness, tremors, hyperthermia, and abdominal pain. The exact mechanism is not known. Most dogs recover with supportive care when the source of exposure is removed.


Corn on the Cob


Corn on the cob can cause intestinal obstruction in dogs which is a very serious condition.

Corn on the cob should not be fed to dogs.


Cat Food


Cat food should not be fed to dogs due to the higher protein and fat levels. The nutritional requirements of a cat are significantly different to a dogs. Likewise, dog food should not be fed to a cat as it lacks taurine which is essential to the health of a cat's heart and eyes.


Alcohol and Hops


Alcoholic beverages pose much the same temptation and hazard to dogs as to humans. A drunk dog displays behaviour analogous to that of an intoxicated person. However, beer presents another problem.  


Hops, a plant used in making beer, can cause malignant hyperthermia in dogs, usually with fatal results. Certain breeds, such as Greyhounds, seem particularly sensitive to hop toxicity, but hops should be kept away from all dogs. Even small amounts of hops can trigger a potentially deadly reaction, even if the hops are "spent" after use in brewing.


Cooked Chicken Bones


Cooked chicken bones can splinter causing either choking or damage to the dog's mouth. It is the cooking process that makes the bones splinter so easily.




Yeast dough can expand once digested causing pain and problems in the dog's stomach and intestines.




Xylitol is a sugar substitute used in chewing gum, chewable vitamins, candy, toothpaste, and other products. Although empirical studies indicate xylitol may be safe for dogs, there have been cases of foods, candies and gums containing xylitol causing toxic or even fatal liver damage in dogs and should be avoided.


Cows Milk


As with cats, most dogs tend to be lactose intolerant.  A puppy has the enzyme lactase, which breaks down the sugar in milk called lactose. Once the dog is weaned, he generally stops producing lactase and loses the ability to digest it. Milk products can then cause an upset stomach and diarrhoea. On the other hand, some dogs can tolerate milk and do enjoy small amounts.




Other foods dogs need to avoid are:


Rhubarb leaves

Mouldy and spoiled foods


Tomato leaves and stems

Potato peelings



Common Household Substances


Some common household chemicals are particularly dangerous to dogs:




Due to its sweet taste, antifreeze poses an extreme danger of poisoning to a dog (or cat) that either drinks from a spill or licks it off its fur. The antifreeze itself is not toxic, but is metabolised in the liver to a compound which causes kidney failure, and eventual seizures, and death. By the time symptoms are observed, the kidneys are usually too damaged for the dog to survive so acting quickly is important. Immediate treatment is to administer apomorphine or peroxide solution in an effort to get the animal to vomit up as much of the antifreeze as possible. Next, it is critical to immediately get the animal to a veterinarian. Fomepizole is considered the preferred treatment for treating ethylene glycol toxicoses in dogs. Ethanol can also be used in cats and dogs, however it does have several unfavourable side effects. Ethanol occupies the enzymes in the dog's liver, long enough for the un-metabolised antifreeze to be passed out harmlessly through the kidneys. Dogs should not be allowed access to any place in which an antifreeze leak or spill has happened until the spill is completely cleaned out. Even a very small amount such as a tablespoon can easily prove fatal. Some brands of antifreeze that contain propylene glycol instead of ethylene glycol are marketed as being less harmful or less attractive to animals.


Mouse and Rat Poison


Mouse and rat poison is commonly found in the house or garage. Dogs readily eat these poisons, which look like small green blocks and are very attractive to them. The poisons work by depleting stores of Vitamin K in the body, without which blood can not clot properly. Symptoms of poisoning include depression, weakness, difficulty breathing, bruising, and bleeding from any part of the body. These symptoms often take 3 to 4 days to show up. A blood test will show that the blood is not clotting properly. If the poison has only recently been ingested (within 2 to 3 hours), the dog should be given apomorphine or hydrogen peroxide to make it vomit. Activated charcoal can be given to absorb any remaining poison in the gastrointestinal tract. Then the dog is given Vitamin K supplementation for 3 to 4 weeks, depending on the type of poison. At the end of treatment, the clotting times should be tested again. The prognosis is good in these cases. However, if the dog is already showing signs of poisoning, it is too late to try and remove the poison from the body. A whole blood transfusion or plasma is given to treat the anaemia and to try and control bleeding. Vitamin K is also given. The prognosis is poor in these cases.

Mouse and rat poisons containing cholecalciferol cause hypercalcemia and hyperphosphatemia in dogs. Symptoms include depression, loss of appetite, vomiting blood, weakness, and shock. Treatment is as above for recent exposure. When hypercalcemia occurs (which can take 1 to 2 weeks), treatment is with intravenous fluids (saline), diuretics, corticosteroids, and calcitonin. Long term prognosis is good once the dog is stabilized.




Zinc toxicity is commonly fatal in dogs where it causes a severe haemolytic anaemia.



If your dog appears unwell and you believe it could be due to something he has consumed, immediately phone your local veterinarian for advice.

Dangerous Foods


Some foods commonly enjoyed by humans are dangerous to dogs:


Grapes and Raisins


It has recently been confirmed that grapes and raisins can cause acute kidney failure in dogs.  The exact mechanism is not known, nor is there any means to determine the susceptibility of an individual dog.  While as little as one raisin can be toxic to a susceptible ten pound dog, some other dogs have eaten as much as a pound of grapes or raisins at a time without ill effects.

The affected dog usually vomits a few hours after consumption and begins showing signs of renal failure three to five days later.