This article reviews seven food items that have been proven toxic to dogs — so if you have a dog, it's important to keep these foods out of their reach.

1.Avocados contain a toxin called persin. Persin is perfectly safe for human consumption but can be very poisonous to dogs.It is found in avocado fruit, pits, leaves and bark, so you should avoid giving any part of the plant to your dog. If a dog eats these, fluid may accumulate in the dog's lungs and chest.This can make it difficult for them to breathe, which can lead to oxygen deprivation and even death.Fluid can also accumulate in the heart, pancreas and abdomen, which can lead to other fatal complications.Avocado pits can also be accidentally swallowed, which can cause choking or a blockage in the digestive tract.

2.Xylitol is a sugar alcohol that is often used to sweeten candy, chewing gum, toothpaste and baked goods. While deemed safe for human consumption, it can be deadly for dogs.Eating foods that contain xylitol can lead to a sudden and significant drop in a dog's blood sugar.Initial symptoms often show up within 30 minutes of consumption and include vomiting, weakness, depression, difficulty moving, coma and seizures.Eventually, xylitol can lead to liver damage and death.

3. Coffee,Tea and Other Caffeine.Caffeine is naturally found in coffee, tea, cocoa and guarana, a South American plant.It is also often added to soft drinks and medications.Caffeine can speed the heart rate and stimulate the nervous system in dogs.Within two to four hours of consuming caffeine, dogs may experience restlessness, excessive thirst, a lack of bladder control, vomiting and diarrhea. If dogs ingest too much caffeine, they can experience abnormal heart rhythm or lung failure, which can ultimately lead to death.In fact, several cases of death have been reported in dogs due to an overdose of caffeine.The minimum dose of caffeine at which death was reported was less than 2.2 mg per pound (1 mg per kg) of body weight.The average cup of coffee or tea contains between 40 and 150 mg caffeine, so even just a few sips could be deadly for a dog.

4.Grapes and raisins can be extremely toxic to dogs.They can cause rapid kidney failure, which can ultimately be fatal.The toxic compounds in grapes are still unknown, but even small amounts can make your dog sick.Toxic levels vary from dog to dog, but one study reviewing 180 reports found that some dogs died after eating just a handful of raisins.Therefore, ingestion of any quantity should be taken very seriously. It is important to note that poisoning can happen from eating raw grapes and raisins, or from eating them as ingredients in baked goods like cookies, cakes and snack bars. Watch for symptoms like vomiting, diarrhea, fatigue and depression.These may be followed by signs of kidney failure, such as excessive thirst and very little urine production.

5. Alcohol and Yeast Dough.Alcohol is found in a variety of products including alcoholic beverages, perfumes, mouthwash, paint, varnish and various cleaning products.While occasional alcohol consumption is safe for humans, dogs cannot tolerate it, even in small amounts. Symptoms usually develop within an hour after consumption and include tiredness, depression, lack of muscle coordination, low body temperature, poor breathing, vomiting and diarrhea.If a dog consumes too much alcohol, it can result in lung failure, seizures, coma and even death.The toxic dose of 100% (or 200 proof) alcohol in dogs has recently been reported to be about 0.59 ounces per pound of body weight (8 ml per kg), with death occurring 12 to 24 hours after ingestion. Alcohol poisoning in dogs usually happens after accidental ingestion of alcoholic beverages.However, in one case, a dog died of alcohol poisoning after eating a large number of rotten apples.It's also a concern if a dog eats raw dough that contains yeast. As the yeast cells ferment, they actually produce alcohol, which causes a dog's blood alcohol level to rise and can ultimately cause alcohol poisoning and death. What's more, the dough will expand in a dog's stomach and can cause severe bloating. This puts pressure on the surrounding organs and can make it very difficult for the dog to breathe.It is important to never feed raw yeast dough or alcohol to your dog. Alcoholic beverages should not be left unattended and raw dough should be kept well out of reach.

6.Chocolate contains the stimulant chemicals theobromine and caffeine, both of which are very difficult for dogs to metabolize.If a dog eats chocolate, it can cause stomach pain, vomiting, diarrhea and dehydration. These symptoms can also progress to more serious problems like heart attacks, internal bleeding, muscle tremors, seizures and death.The severity of the side effects depends on how large the dog is, and how much and what type of chocolate it has consumed.The darker and less sweet the chocolate, the more toxic it will be to your dog.Unsweetened baker's chocolate and cocoa powder are among the most dangerous varieties. According to the Merck Veterinary Manual, dogs may show symptoms after ingesting as little as 44 mg per pound (20 mg per kg) of body weight.In other words, about 1 ounce (28 grams) of a baker's chocolate bar would be enough to cause toxic symptoms in a 44-pound (20-kg) dog. It is most common for dogs to experience chocolate poisoning on holidays like Valentine's Day, Easter, Halloween and Christmas — presumably because these are times when people often have chocolate on hand.No matter the occasion, it is important to always keep chocolate out of reach.

7.Eating too much salt could lead to a condition known as salt poisoning or water deprivation in dogs.This can cause vomiting, diarrhea, depression, tremors, fever and seizures. It may even be fatal in severe cases. According to the Merck Veterinary Manual, the toxic dose for dogs is around 2.2 teaspoons of salt per pound (4 grams per kg) of body weight.Because of this, it is not a good idea to give your dog salted foods like pretzels, popcorn or chips.It is also important to make sure your dog always has access to fresh drinking water.

Other Foods That May Be Harmful to Your Dog Onions, garlic and chives: These can damage a dog's red blood cells and cause anemia. In severe cases, your dog could require a blood transfusion. Milk and dairy products: Like humans, dogs can become intolerant to lactose over time. Consuming milk and dairy products may lead to vomiting, diarrhea and other digestive problems in dogs. Macadamia nuts: These contain an unknown toxin that can cause weakness, muscle tremors and vomiting in dogs. Because of their high fat content, macadamia nuts can also lead to pancreatitis, or an inflamed pancreas. Apples, apricots, cherries, peaches and plums: Their seeds or pits contain cyanide, which is poisonous. Eating them can lead to some pretty serious side effects, including digestive problems.