Hazardous Cuisine:
Foods We Can Enjoy Can Be
Toxic to Our Pets

Could something as small as a crumb of blue cheese make your pet sick?

By Manda S.W. Kaplan

November / December 2009

One little piece of Gorgonzola, Roquefort or other blue mold-enhanced cheese can hurt your pet, as could onions, garlic, grapes, avocados, chocolate and other foods that people take for granted as harmless and even healthful. In particular, moldy cheeses may contain substances called tremorgenic mycotoxins, which in pets can lead to muscle tremors, loss of coordination, and even convulsions lasting for several days. While the exact mechanism of action is not yet known, studies show that symptoms can vary from mild to severe, depending on the strength of the particular mold ingested.

Other “people foods” that should never be given to pets include:

• Onions, chives, leeks, shallots and garlic. Members of the genus Allium, these plants can damage red blood cells, possibly resulting in anemia in both cats and dogs, says Heather Troyer, DVM, Diplomate ABVP, of the Oradell Animal Hospital in Paramus, New Jersey. She advises pet owners to be careful with cooked or raw pieces of onion and garlic, and even onion and garlic powder. Baby foods that contain onion or garlic powder, Troyer adds, have been reported to cause toxicity in cats. Symptoms associated with onion and garlic poisoning include vomiting and weakness.

• Grapes and raisins. They have been shown to cause kidney failure in dogs. The veterinary community is still studying this issue, as the basis for grape-related kidney failure is unclear. Since the exact amount of fruit that may cause toxicity is unknown, any amount could potentially be dangerous. Holly Thompson, DVM, an emergency/critical care specialist at Oradell Animal Hospital, says that some dogs—regardless of size or breed—may be sickened by one grape, while others could eat a handful without a problem. “Since we don’t know yet how to identify sensitive animals, all owners should avoid feeding grapes or raisins to their dogs,” Thompson advises.

• Avocados. These fruits contain persin, a compound that can cause vomiting and diarrhea in dogs, while birds and rodents are even more critically affected by avocado poisoning. In these small animals, ingestion can lead to fluid accumulation around the heart followed by difficulty breathing and, in some cases, death–especially in birds.

• Macadamia nuts. These nuts can cause serious problems for dogs. Thompson says dogs may be unable to stand or use their hind legs within a few hours of eating macadamia nuts. In one study, clinical signs commonly reported in dogs that have ingested even small amounts of macadamia nuts include depression, weakness, vomiting, lack of coordination, tremors and hyperthermia. In most cases, dogs developed these signs less than 12 hours after eating the nuts. Thompson recalls when two-year old Lucky, a male Golden Retriever, arrived at the emergency service. The dog had lost almost all control over his hind legs and was twitching uncontrollably. Medications, household chemicals and garbage ingestion were ruled out. He was examined by generalists, emergency doctors and even a neurologist, and still no cause could be found for Lucky’s ailment. Thompson returned to the dog’s family, asking them to remember anything he could have ingested. They told her that all he had eaten that day was his kibble, maybe some grass outside and the cookie he’d stolen off the coffee table a few hours earlier—an oatmeal macadamia nut cookie. The mystery was solved and Lucky eventually recovered after treatment.

• Bread dough. When you are baking bread or pizza, be careful handling the dough. If a dog eats raw dough, her body heat will cause it to expand several times its original size in her stomach, just as it would in a warm oven. Signs seen with bread dough ingestion are associated with alcoholic byproducts of the fermenting yeast (apparent drunkenness and vomiting) and obstruction of the gastrointestinal tract by the expanded dough (severe abdominal pain, bloating, vomiting, poor coordination and depression).

• Chocolate, coffee and caffeine. If your dog fancies herself a chocoholic, give her doggie cookies made with carob instead. Veterinary nutritionist Laura Eirmann, DVM, of Oradell Animal Hospital, warns that chocolate, coffee and similar foods can be dangerous for pets. They all contain methylxanthines. When a pet eats a food product containing methylxanthines, the result can be sensitivity to touch (a dog will actually jump when touched), panting, hyperactivity, diarrhea, vomiting, excessive thirst and urination, tremors, seizures, abnormal heart rhythms and even death. The darker the chocolate, the more dangerous it is; baking chocolate is the most dangerous type.

So while it’s healthy to add a few fruits and veggies into Fido’s diet, be careful in your choices. Carrots are usually a good treat to share with a healthy dog, but it’s always best to ask your veterinarian before feeding anything new to your pets.