The ASPCA Animal Poison Control Center wants to educate pet owners and veterinarians on the five most potentially dangerous plants to cats, dogs and other companion animals.
According to data compiled by the Center from January 2001 to December 2004, the most commonly reported plants with the potential to produce life-threatening problems in pets were Lily, Azalea, Oleander, Sago Palm and Castor Bean.
"We typically recommend that pets not be allowed to eat plants in general," says Dr. Safdar Khan, Veterinary Toxicologist for the ASPCA Animal Poison Control Center. "However, it is especially critical that these plants be kept out of the reach of animals, as they have the potential to cause serious, even fatal systemic effects when ingested."
Lilies rank number one in dangerous plant call volume, with over 45% of the top five deadliest plant calls involving lilies.
Both Lilium and Hemerocallis species are very popular flowering plants that can be found in gardens and floral bouquets across the country at various times of the year. However, they are considered to be highly toxic to cats, and "while the poisonous component in lilies has not yet been identified," states Dr. Khan, "it is clear that with even ingestions of very small amounts of the plant, severe kidney damage could result." An owner in eastern Pennsylvania unfortunately lost her cat to kidney failure in April 2004 from ingesting only a small portion of an Easter Lily plant.
Azaleas (Rhododendron spp.) are indigenous to the wooded and mountainous regions of the Eastern and Western United States, and are also commonly used in landscaping as an ornamental plant.
Azaleas contain substances known as grayanotoxins, which Dr. Khan says can produce vomiting, drooling, diarrhea, weakness and central nervous system depression in dogs, cats and other animals. Severe azalea poisoning could ultimately lead to coma and death from collapse of the cardiovascular system. While Oleander is a native plant of the Mediterranean and Asia, like Azalea it is frequently used as an ornamental plant in the U.S. "All parts of the Oleander plant (Nerium oleander) are considered to be toxic," says Dr. Khan, "as they contain cardiac glycosides that have the potential to cause serious effects including gastrointestinal tract irritation, abnormal cardiac function, a significant drop in body temperature (hypothermia) and even death." In late summer 2003, a border collie in central Colorado developed serious cardiac effects after ingesting a few Azalea leaves, while a cat in southern California began vomiting and became very depressed from nibbling on an Oleander plant. Both pets fortunately recovered after treatment at local veterinary hospitals.
Sago Palm (Cycas revoluta) and other Cycas species can also be potentially deadly to pets.
These popular ornamental plants, native to subtropical climates such as the Southern United States, contain toxic compounds that Dr. Khan states "can potentially produce vomiting, diarrhea, depression, seizures and liver failure." All parts of the plant are poisonous, but the seeds or "nuts" appear to contain the largest amount of toxins. As with the other plants on this list, very little plant material can produce a poisoning; the ingestion of just one or two seeds can result in very serious effects. An American Pit Bull Terrier in northern Florida became very ill and subsequently died from liver failure in March 2002 after chewing on the leaves and base of a Sago Palm in his owner's yard.
As with Sago Palm, the beans or seeds of the Castor Bean plant (Ricinus communis) are the most toxic portion, as they contain the highest concentration of poisonous component and according to Dr. Khan, are particularly dangerous if chewed or crushed. However, the leaves, stem and other parts are toxic as well.
Castor Bean plants are indigenous to the tropical regions of Africa and the West Indies, but have become a part of the natural foliage of the southern portions of the U.S. and are used as an ornamental plant in many American gardens. In the Castor Bean plant, the poisonous principle is ricin, a highly toxic protein that can produce severe abdominal pain, drooling, vomiting, diarrhea, excessive thirst, weakness and loss of appetite. In severe cases, dehydration, muscle twitching, tremors, seizures, coma and death can be seen. In August 2002, a Labrador Retriever in southern Arizona developed serious gastrointestinal irritation including bloody diarrhea and vomiting after ingesting several castor bean seeds; her condition required intensive care at a local emergency clinic.