The American Society for the Prevention of Cruelty to Animals ranked plants as the eighth leading cause of pet poisonings in 2012. While cats were more likely to get into plant trouble, curious canines digging up deadly spring bulbs or grazing on toxic greenery were well represented among the more than 7,000 calls to the society’s poison hotline in 2012. The ASPCA offers a lengthy list of plants that are toxic to dogs.
Making the List
The ASPCA's online list includes a printable format and plant photos for ID assistance. There’s also a lengthy list of pet-safe plants; you don’t have to sacrifice gardening for the sake of four-legged family members. The website of The Humane Society of the United States also provides an extensive print-ready list of the more than 700 plants potentially toxic to animals.
Some listed plants may come as a surprise since they’re safe for humans. For instance, garlic (Allium sativum) and hops (Humulus lupulus), an ingredient in beer, are toxic to dogs. Grapes (Vitis spp) from wild or cultivated vines that grow in U.S. Department of Agriculture plant hardiness zones 2 to 10 can cause kidney failure if ingested in large amounts. Herbs that present doggy danger include yarrow (Achillea millefolium), hardy in USDA zones 3 to 9, and succulent aloe (Aloe vera), USDA zones 10 to 12.
Related plants don't always share the same properties. Plant lists are a necessity for sorting out the Lilaceae family, for example, whose many permutations are a familiar sight in USDA zones 4 to 10. Although the daylily (Hemerocallis) is a known cat killer, it's not harmful to dogs. Hosta (Hosta plantaginea), on the other hand, causes gastrointestinal upset.
Among the Worst
The ornamental Sago palm (Cycas revoluta), winter hardy to USDA zones 9 and 10, is highly toxic. The entire plant is poisonous; seed pods are especially attractive to pets and children. Ditto the deadly temptation of the fast-growing castor bean (Ricinus communis). The once-prized fatally poisonous ornamental has no place in the family garden. Rich in the toxic protein ricin, castor bean is hardy in USDA zones 8 to 11 and may self-seed in cooler climates. Because of invasive tendencies, sale and propagation are banned in some regions, but it's still found in the wild. Ingesting tiny amounts causes burning mouth and throat, diarrhea and vomiting. In larger amounts, it kills.
If your dog exhibits poisoning symptoms, which can include depression, anorexia and tremors as well as the typical gastrointestinal distress, carefully collect any materials that may have been ingested, regurgitated or excreted. Wear gloves or use a shovel or plastic spoon. Place contents in a tight-closing container such as a zip-top bag or jar with a lid. Contact your veterinarian immediately. Acting fast can make a life-or-death difference.
The ASPCA staffs a 24-hour poison hotline at 1-888-426-4435. The Pet Poison Helpline, recommended by the American Animal Hospital Association, offers services to the United States, Canada and the Caribbean. The U.S. hotline number is 1-800-213-6680. Both websites charge a per-incident consultation fee, but both also include a host of fast and free info, particularly Helpline's plant search.
Safeguard your yard by removing or fencing off dangerous plants. Some may only present a hazard at specific times of the year. For example, when a black walnut tree (Juglans nigra), found in USDA zones 4 to 9, drops its nuts, prompt raking and removal prevents exposure to a toxin that decomposing nuts secrete which can cause tremors and seizures. Don't allow your dog to roam unsupervised in areas where poisonous plants may be present.
For help identifying plants, tap the state university cooperative extension service, a nationwide network with regional offices that assists by hooking you up with local experts including certified Master Gardeners.