While Styrofoam isn't considered toxic to your dog if he ingests it, it can be a choking hazard according to the Partnership for Animal Welfare.
Depending on the amount of Styrofoam your pet has ingested, it could lead to a potentially fatal intestinal blockage, warns the Dog Breed Info Cente.
Many common household items can pose a threat to our animal companions, even some items specifically meant for pets could cause health problems. To protect your pet, you need to take the same precautions you would with a child.
Rodent poisons and insecticides are the most common sources of companion animal poisoning. See list of Common Household Dangers for Pets at The Humane Society of the United States.
Check out some diet and nutrition tips for a healthy dog from Pets - WebMD.
Find out what to do if your dog or cat is poisoned at Pet Poison Helpline.