"HEALTH ALERT: SEASONAL PRODUCE THAT CAN HARM YOUR PETS
oranges and apples, cherries and lemons and apples, oh my! While summer fruits are good for you, certain parts of these seasonal offerings can be potentially irritating—and in some situations, occasionally toxic—to companion animals.

According to experts at the ASPCA Animal Poison Control Center, the peels, fruit and seeds of citrus plants such as lemons, oranges, limes and grapefruits contain varying amounts of citric acid, limonin and volatile oils that can cause gastrointestinal irritation and result in vomiting and diarrhea. As for apples, cherries, peaches and apricots, their stems, leaves and seeds contain cyanogenic glycosides that have the potential to cause vomiting and loss of appetite—and in severe cases, weakness, difficulty breathing, hyperventilation, shock and even death.

“Typically, these severe effects develop from very large ingestions of plant material, more likely to occur with grazing animals such as horses or other livestock,” says the ASPCA’s Dana Farbman, CVT. “The consumption of a few segments of citrus fruit, an apple or two, or a few cherries would usually not be expected to cause serious problems beyond perhaps minor stomach upset. However, it is important for animal owners to be aware of the potential for problems that these fruit trees can produce.”

As a responsible pet parent, it’s always a good idea to become familiar with different types of plants in and around the home—and make sure that potentially poisonous species are not accessible to your pets. For lists of both safe and potentially toxic plants, please visit the ASPCA Animal Poison Control Center online."

from the ASPCA web site.