Chocolate contains toxic substances called methylxanthines, which are stimulants that stop a dog’s metabolic process. Even just a little bit of chocolate, especially dark chocolate, can cause diarrhea and vomiting.
Allium family: onions, leeks, chives, garlic
Eating onions can cause your dog’s red blood cells to rupture, and can also cause vomiting, diarrhea, stomach pain, and nausea. Poisoning from onions is more serious in Japanese breeds of dogs like Akitas and Shiba Inus, but all dogs are very susceptible to it.
Macadamia nuts & Almonds
Macadamia nuts, part of the Protaceae family, can cause vomiting, increased body temperature, inability to walk, and lethargy. Even worse, they can affect the nervous system. Almonds may not necessarily be toxic to dogs like macadamia nuts are, but they can block the esophagus or even tear the windpipe if not chewed completely.
The pit, skin, and leaves of avocados contain persin, a toxin that often causes vomiting and diarrhea in dogs. The fleshy inside of the fruit doesn’t have as much persin as the rest of the plant, but it is still too much for dogs to handle.
Certain Fruits: Grapes & Cherries
With the exception of the fleshy part around the seed, cherry plants contain cyanide and are toxic to dogs. Cyanide disrupts cellular oxygen transport, which means that your dog’s blood cells can’t get enough oxygen. If your dog eats cherries, be on the lookout for dilated pupils, difficulty breathing, and red gums, as these may be signs of cyanide poisoning. Grapes and raisins have proved to be very toxic for dogs no matter the dog’s breed, sex, or age. In fact, grapes are so toxic that they can lead to acute sudden kidney failure.