Toxic Food & Plants For Dogs - Onion

Onions are toxic to dogs. The toxicity is dose dependent, so the bigger the dog, the more onion need be consumed to cause toxicity.

Onion toxicity causes a Heinz body anemia. Heinz bodies are small bubble-like projections, which protrude from a red blood cell and can be seen when the cells are stained. This "bubble" is a weak spot in the red blood cell and, therefore, the cell has a decreased life span and ruptures prematurely.
If numerous red cells are affected and rupture, anemia can result. It is a form of hemolytic anemia. Onions are only one of the substances, which can cause Heinz body anemia. Other substances such as Acetaminophen (Tylenol) and Benzocaine (used as a topical pain reliever, or in cough drops) can also cause Heinz body anemia in the dog.
All forms of onion can be a problem including dehydrated onions, raw onions, cooked onions and table scraps containing cooked onions. Left over pizza, Chinese dishes and commercial baby food containing onion.

The hemolytic episode usually occurs several days after onion ingestion (lowest hematocrit around day 5 post ingestion). Daily feeding of onions could have a cumulative effect due to ongoing formation of Heinz bodies versus a single exposure with a wide gap until the next exposure, allowing the bone marrow time to regenerate the prematurely destroyed red cells.
Symptoms include labored breathing, liver damage, vomiting, diarrhea, and discolored urine.

While garlic also contains the toxic ingredient thiosulphate,
It is safe for your dog used in moderation and can help with a myriad of things such as gas, flea prevention and it has natural antibiotic properties.

Toxic Food & Plants For Dogs - Chocolate

Chocolate contains theobromine, a compound that is a cardiac stimulant and a diuretic.

The signs of sickness may not be seen for several hours, with death following within twenty-four hours. Symptoms include Staggering, labored breathing, vomiting, diarrhea, abdominal pain, tremors, fever, heart rate increase, arrhythmia, seizures, coma, and death.

Cocoa powder and cooking chocolate are the most toxic forms. A 10-kilogram dog can be seriously affected if it eats a quarter of a 250gm packet of cocoa powder or half of a 250gm block of cooking chocolate. These forms of chocolate contain ten times more theobromine than milk chocolate. Thus, a chocolate mud cake could be a real health risk for a small dog. Even licking a substantial part of the chocolate icing from a cake can make a dog unwell.

Semi-sweet chocolate and dark chocolate are the next most dangerous forms, with milk chocolate being the least dangerous. A dog needs to eat more than a 250gm block of milk chocolate to be affected. Obviously, the smaller the dog, the less it needs to eat.

Toxic Food & Plants For Dogs - Cyclamen

Cyclamen is a genus of 23 species of perennials growing from tubers, valued for their flowers with upswept petals and variably patterned leaves. Cyclamen species are native from Europe and the Mediterranean region east to Iran, with one species in Somalia.

Cyclamen contain the toxic principal cyclamine. While the largest concentration of this toxic principal is generally contained within the tuber, the rest of the plant may also contain some level of cyclamine. Because of this, we consider the whole plant to have at least some degree of toxic potential to dogs.

It is important to remember that just because the tubers are underground when they are planted does not necessarily mean that a dog will not consume them. It is not at all uncommon for dogs to dig up and ingest entire plants, leaves, stems, bulbs, tubers, roots and all!  Dogs will even eat the plant straight out of a package that was brought home from the store.

The toxic principles of cyclamen is terpenoid saponins

The clinical signs are salivation, vomiting, diarrhea. following large ingestions of tubers: heart rhythm abnormalities, seizures, and death.