1. Chocolate or coffee
Vomiting, rapid heart rate and signs of anxiety can be seen with the ingestion of as little as 1/4 ounce of baking chocolate by a 10 pound dog. Coffee can produce the same effects.
2. Christmas tree preservative/water
Preservative may contain fertilizers, which, if ingested, can upset the stomach. Stagnant tree water can be a breeding ground for bacteria, which can also lead to vomiting, nausea, and diarrhea.
3. Ornaments, ribbons, tinsel
While none of these are directly toxic, ribbon and tinsel can cause life-threatening gastrointestinal blockage.
4. Holiday plants: holly, mistletoe, lilies, poinsettia
Eating holly could produce nausea, vomiting, diarrhea, and lethargy. If a dog or cat ingests mistletoe, gastrointestinal upset and possibly even cardiovascular problems could result. All parts of lilies are highly toxic to cats, with the potential to produce life-threatening kidney failure even from small ingestions. While the toxic potential of poinsettia has been greatly exaggerated, mild stomach upset could still occur if ingested.
5. Yeast dough
If swallowed, uncooked yeast dough can rise in the stomach and cause extreme discomfort. Pets may experience abdominal pain, bloat, vomiting, disorientation, and depression. Since a breakdown product of rising dough is alcohol, it can also cause alcohol poisoning. Many yeast ingestions require surgical removal of the dough, and even small amounts can be dangerous.
6. Table food (fatty, spicy), moldy foods, poultry bones
Poultry bones can splinter and cause damage or blockage in the gastrointestinal tract. Spicy or fatty foods could possibly lead to inflammation of the pancreas. Moldy or spoiled foods could produce food poisoning, tremors, or seizures.
7. Macadamia nuts
In dogs, ingestions can produce vomiting, weakness (particularly in the hind legs), depression, lack of coordination, and tremors.
8. Alcoholic beverages
If ingested, alcohol can potentially result in vomiting, diarrhea, lack of coordination, central nervous system depression, difficulty breathing, tremors, acidosis, coma, and even death.
9. Grapes, raisins
Ingestion of raisins and grapes have been associated with acute kidney failure in dogs.