Sometimes the danger is specific to particular animals. Yew (Taxus spp.), for example, is so deadly for cats and dogs that a dog need only eat 1/10 of 1 percent of its body weight to die. However, deer feast on yew and birds scarf up the berries with no apparent harm. Native Americans fed dogs fireweed (Epilobium angustifolium), yet it's poisonous to cats. Equally toxic, but primarily to cats, are most lilies (Lilium spp.). Simply ingesting two flower petals or minute bits of stems and leaves can result in renal failure and death.
The American Society for the Prevention of Cruelty to Animals (ASPCA) has a list of plants that are toxic to cats, dogs, and horses on its website at aspca.org/pet-care/poison-control/plants. If you suspect your pet has ingested a harmful substance, call your veterinarian. But if the animal is having seizures, losing consciousness, or having difficulty breathing, telephone ahead and take the animal immediately to your veterinarian or the nearest emergency veterinary clinic. The ASPCA's Poison Control Center (888-426-4435; $65 consultation fee) and Pet Poison Helpline (800-213-6680; $39 consultation fee) are both staffed around the clock to assist with emergencies.
4 Plants Toxic to Dogs
Azalea (Rhododendron spp.). Ingestion of just a few leaves can cause digestive upset, drooling, loss of appetite, weakness, leg paralysis, or even death.
Apple (Malus spp.). Seeds contain cyanogenic glycosides (cyanide). Ingesting enough seeds can provide a fatal dose.
Grape (Vitis spp.). Symptoms include vomiting, diarrhea, weakness, increased drinking, abdominal pain, and kidney failure. Even if consumed in low quantities over a period of time, the result can be fatal.
Cherry, plum, peach (Prunus spp.). Leaves and seeds contain cyanogenic glycosides, which can cause dilated pupils, difficulty breathing, shock, and death.
4 Plants Toxic to Cats
Ivy (Hedera spp.). Leaves and berries can cause stomach irritation, diarrhea, coma, or death.
Tulip (Tulipa spp.). These bulbs can damage a cat's mouth and esophagus and cause vomiting, severe diarrhea, and abnormal heart rhythms. Hyacinths and daffodils are also harmful.
Castor bean (Ricinus communis). All parts, but mostly seeds, if chewed, will cause nausea, abdominal pain, bloody diarrhea, excessive thirst, muscle twitching, convulsions, or coma.
Larkspur (Consolida ajacis). Plants and seeds can cause digestive upset, nervous excitement, or depression. Potentially fatal.