Avocado
They contain a toxic component called persin, which can damage heart, lung and other tissue in many animals.
This fruit is very toxic to dogs, cats and most animals.

Beer
Alcoholic beverages can cause the same damage to an animal's liver and brain as they cause in humans. But the effects can be deadly on animals since they are much smaller than us. The smaller the animal, the more deadly the effects can be. Even a small amount of alcohol may cause vomiting and damage the liver and brain.

Nuts
Walnuts and macadamia nuts are especially toxic. Effects can be anything from vomiting to paralysis to death. Within 12 hours of eating the nuts, pets start to develop symptoms such as an inability to stand or walk, vomiting, hyperthermia (elevated body temperature), weakness, and an elevated heart rate. These symptoms can be even worse if your dog eats some chocolate with the nuts. The effect can cause kidney failure, often leading to death.

Chocolate
Chocolate contains theobromine, which can kill your pet if eaten in large quantities. Dark and unsweetened baking chocolates are especially dangerous. Giving your pup a piece of chocolate cake or even letting him lick the chocolate icing on the cake could cause him to become ill. Theobromine can also cause a dog or cat's heart to beat very rapidly or irregularly, which could result in death if the pet is exercising or overly active.

Candy
Candy or anything containing Xylitol (a common sweetener found in some diet products) can cause a sudden drop in an animal's blood sugar, loss of coordination and seizures. If left untreated, the animal could die.

Caffeine
Coffee, tea or any product that contains caffeine stimulates an animal's central nervous and cardiac systems. This can lead to restlessness, heart palpitations and death, depending on how much the animal consumes.

Grapes & Raisins
Grapes and raisins can lead to kidney failure in dogs. As little as a single serving of raisins can kill them. And the effects are cumulative, which means that even if a dog eats just one or two grapes or raisins regularly, the toxin that builds in his system will eventually kill him.

Onions
Onions are another common food that can be highly toxic to pets. They can destroy an animal's red blood cells and lead to anemia, weakness and breathing difficulties. Their effects are also cumulative over time.

Medicine
Hide medicine from your pets just like you would from your children. The most common cause of pet poisoning is from animals ingesting a medicine or drug normally prescribed for humans.

And this is not just because furry pals are getting into their pet parent's medicine cabinets. In many cases, pet owners give their feline and canine friends an over-the-counter medication to ease an animal's pain. But acetaminophen and ibuprofen, the active ingredients in many common pain relievers, are extremely toxic to dogs and cats. They can cause gastric ulcers, liver damage, kidney failure and sometimes death.