Garden Poisonings: 10 Plants That Are Toxic to Pets

Flora and fauna don’t always get along. For dogs and cats, the risk of ingesting plants with toxicity increases with the arrival of spring and a rise in outdoor activities, such as gardening or hiking. If a pet ingests a toxic plant, early diagnosis and treatment depend on quickly identifying the toxins involved. It’s best to act immediately, because by the time symptoms appear, it may already be too late to save the animal.   Certain plants and plant-based substances can cause severe and potentially fatal poisoning in pets. > Daffodils and narcissus These flowers contain lycorine, a natural alkaloid that triggers vomiting. Ingestion of the bulb or any part of the plant can cause, in addition to vomiting, diarrhea, abdominal pain, heart rhythm abnormalities, and respiratory distress.   > Tulips and hyacinths The allergenic lactones found in tulips, as well as the alkaloids in hyacinths, can cause excessive salivation, vomiting, and diarrhea, leading to dehydration and even other complications. Ingesting larger amounts (especially the bulb) can cause more severe symptoms, including an increased heart rate and respiratory distress. All parts of these plants are toxic, but the lactones and alkaloids are primarily concentrated in the bulbs.   > Lilies Some of these flowers (peace lily, Peruvian lily, and calla lily) contain oxalate crystals that have a mild toxicity. However, other varieties are much more dangerous (tiger lily, daylily, Asian and Oriental lilies, and Easter lily), and ingestion is often fatal, particularly in cats. What makes lilies so toxic remains a mystery, but ingesting even a small part of the plant can cause acute renal failure within 36 to 72 hours. The first symptoms appear within a few hours and may include loss of appetite, lethargy, and vomiting. Even ingesting pollen—or even the water from the vase—can prove fatal. The prognosis is very poor for cats but good for dogs (moderate gastrointestinal distress). > Lily of the Valley This plant contains cardiotonic glycosides, sugars that affect how the heart muscle contracts. Ingestion of any part of the plant can cause vomiting, diarrhea, a slowed heart rate, abnormal heart rhythms, or even seizures. The toxicity of the dose is not well understood, but ingesting even a single stem can cause symptoms in a small animal. Ingesting several berries, leaves, or stems requires emergency treatment.   > Crocus Both species of crocus—those that bloom in the spring and those that bloom in the fall—cause vomiting and diarrhea when ingested. However, the fall crocus (colchicum) has the highest level of toxicity: it contains colchicine and other alkaloids that can even inhibit cell division and cause vomiting, gastrointestinal bleeding, liver and kidney damage, and respiratory failure. Lactones and pyrethrins, as well as other potential irritants found in these plants, can irritate the gastrointestinal tract and affect the nervous system. Signs of toxicity include vomiting, diarrhea, excessive salivation, and loss of coordination.   > Cyclamen The tubers or rhizomes of this plant contain terpenoid saponins, which are composed of glycosides that attack and destroy red blood cells. Ingestion of these toxins leads to excessive salivation, vomiting, diarrhea, loss of appetite, convulsions, and heart rhythm abnormalities.   > Tulips and hyacinths The allergenic lactones found in tulips, as well as the alkaloids in hyacinths, can cause excessive salivation, vomiting, and diarrhea, leading to dehydration and even other complications. Ingesting larger amounts (especially the bulb) causes more severe symptoms, including an increased heart rate and respiratory distress. All parts of these plants are toxic, but the lactones and alkaloids are primarily concentrated in the bulbs.   > Cycads (Japanese cycas, zamioculcas, etc.) All parts of these false palms are toxic and can even be fatal. These plants contain cycasin and ß-methylamino-L-alanine, two compounds that are toxic to the nervous system and the liver if ingested. Symptoms include vomiting, lethargy, melena, jaundice, polydipsia, hemorrhagic gastritis, bruising, blood clots, liver failure, and paralysis. Ingesting just one or two seeds is sufficient and can be fatal. > Pink laurel The leaves and flowers of this shrub have extreme toxicity if ingested by an animal. The entire plant (wood, leaves, flowers, seeds, sap) contains both irritants and cardiotoxic substances. Symptoms primarily affect the digestive and cardiovascular systems, followed by the nervous and respiratory systems, and the outcome is fatal. Just two or three leaves are enough to kill a 10-kg dog.   To prevent poisoning, all these plants should be kept out of gardens where dogs and cats roam. If ingested, immediate veterinary care is essential . Being able to identify the symptoms of toxicity also allows for a rapid assessment of the severity of the situation. Early and appropriate treatment will, in most cases, halt the symptoms of toxicity. Without treatment, the prognosis is often poor.