• Leek – Toxic to dogs, cats, and horses. Clinical signs include vomiting, breakdown of red blood cells (hemolytic anemia, Heinz body anemia), blood in urine, weakness, high heart rate, panting.
• Lemon – Toxic to dogs, cats, and horses. Fruit is edible, skins and plant material can cause problems. Clinical signs include vomiting, diarrhea, depression, and potential dermatitis.
• Lemon Grass – Toxic to dogs, cats, and horses. Clinical signs include stomach upset in dogs and cats. Horses may experience difficulty breathing, weakness, and death (rare).
• Lily – Toxic to dogs and cats. Clinical signs include vomiting and diarrhea. Large intake causes convulsions, low blood pressure, tremors, and cardiac arrhythmia. Can cause kidney failure in cats.
• Lime – Toxic to dogs, cats, and horses. Fruit is edible, skins and plant material can cause problems. Clinical signs include vomiting, diarrhea, depression, and potential dermatitis.
• Locust – Toxic to dogs, cats, and horses. Clinical signs include vomiting, depression, anorexia, weakness, difficulty breathing, diarrhea (bloody), death.
• Lucky Bamboo – Toxic to dogs and cats. Clinical signs include vomiting, diarrhea, abdominal pain, weakness, and lack of coordination.
• Macadamia Nut (Australian Nut, Queensland Nut) – Toxic to dogs. Clinical signs include depression, hyperthermia, weakness, muscular stiffness, vomiting, tremors, increased heart rate.
• Marijuana – Toxic to dogs, cats, and horses. Clinical signs include prolonged depression, vomiting, incoordination, sleepiness or excitation, hypersalivation, dilated pupils, low blood pressure, low body temperature, seizure, coma, death.
• Marjoram – Toxic to dogs and cats. Clinical signs include vomiting and diarrhea.
• Milkweed – Toxic to dogs, cats, and horses. Clinical signs include vomiting, profound depression, weakness, anorexia, and diarrhea. May be followed by seizures, difficulty breathing, rapid, weak pulse, dilated pupils, kidney or liver failure, coma, respiratory paralysis, and death.
• Mint – Toxic to dogs, cats, and horses. Clinical signs include vomiting and diarrhea with large ingestions.
• Mistletoe – Toxic to dogs, cats, and horses. Clinical signs include vomiting, diarrhea, low blood pressure (rare), difficulty breathing, and low heart rate.
• Morning Glory – Toxic to dogs, cats, and horses. Clinical signs include vomiting. Large amounts of seeds may cause hallucinations.
• Mother-in-Law’s Tongue (Snake Plant, Golden Bird’s Nest, Good Luck Plant) – Toxic to dogs and cats. Clinical signs include nausea, vomiting, diarrhea.
• Oak – Toxic to horses. Clinical signs include abdominal pain, constipation then diarrhea (occasionally bloody), depression, frequent urination, discolored urine, and jaundice.  Acorns can obstruct digestive tract.
• Oleander – Toxic to dogs, cats, and horses. Clinical signs include, drooling, abdominal pain, diarrhea, colic, depression, and death.
• Onion – Toxic to dogs, cats, and horses. Clinical signs include vomiting, breakdown of red blood cells (hemolytic anemia, Heinz body anemia), blood in urine, weakness, high heart rate, panting.
• Orange – Toxic to dogs, cats, and horses. Fruit is edible, skins and plant material can cause problems. Clinical signs include vomiting, diarrhea, depression, and potential dermatitis.
• Oregano – Toxic to dogs, cats, and horses. Clinical signs include mild vomiting and diarrhea.
• Parsley – Toxic to dogs, cats, and horses. Clinical signs include photosensitization (sunburn, dermatitis) when ingested in large amounts.
• Peach – Toxic to dogs, cats, and horses. Stems, leaves, and seeds contain cyanide, particularly in the process of wilting. Clinical signs include brick red mucous membranes, dilated pupils, difficulty breathing, panting, shock.
• Peony – Toxic to dogs, cats, and horses. Clinical signs include vomiting, diarrhea, and depression.
• Periwinkle – Toxic to dogs, cats, and horses. Clinical signs include vomiting, diarrhea, low blood pressure, depression, tremors, seizures, coma, and death.
• Philodendron – Toxic to dogs, cats, and horses. Clinical signs include oral irritation, pain and swelling of the mouth, tongue and lips, excessive drooling, vomiting (not in horses), difficulty swallowing.
• Poinsettia – Toxic to dogs, cats, and horses. Clinical signs include irritation to mouth and stomach, sometimes causing vomiting.
• Privet – Toxic to dogs, cats, and horses. Clinical signs include gastrointestinal upset (most common), incoordination, increased heart rate, and death (rare).
• Rhododendron – Toxic to dogs, cats, and horses. Clinical signs include vomiting, diarrhea, hypersalivation, weakness, coma, hypertension, depression, cardiovascular collapse, and death. The toxic principle interferes with normal skeletal muscle, cardiac muscle, and nerve function.
• Sago Palm – Toxic to dogs, cats, and horses.  All parts of the Sego Palm are considered poisonous, with the seeds being the most toxic part of the plant. Clinical signs include drooling, weakness, seizures, tremors, vomiting, diarrhea, lethargy, abdominal pain, jaundice, black-tarry stool, liver damage, severe liver failure, and death.

       CALL Your Veterinarian immediately for life-saving recommendations if you suspect           your pet ate Sago Palm.

• Shamrock Plant – Toxic to dogs, cats, and horses. Clinical signs include kidney failure (rare in dogs and cats), tremors, salivation.
• Sweet Pea – Toxic to dogs, cats, and horses. Clinical signs include weakness, lethargy, pacing, head pressing, tremors, seizures, and possible death.
• Tarragon – Toxic to dogs, cats, and horses. Clinical signs include mild vomiting and diarrhea.
• Tobacco – Toxic to dogs, cats, and horses. Clinical signs include hyperexcitability then depression, vomiting, incoordination, paralysis, and possible death.
• Tomato Plant – Toxic to dogs, cats, and horses. Clinical signs include hypersalivation, inappetence, severe gastrointestinal upset, depression, weakness, dilated pupils, slow heart rate. The ripened fruit of the plant is considered non-toxic.
• Tulip – Toxic to dogs, cats, and horses. Clinical signs include vomiting, depression, and hypersalivation. Highest concentration of toxin in bulb.
• Wisteria – Toxic to dogs, cats, and horses. Clinical signs include vomiting (sometimes with blood), diarrhea, and depression.
• Yucca – Toxic to dogs, cats, and horses. Clinical signs include vomiting in dogs and cats, liver disease and dermatitis in horses.

What to do if your pet has ingested a potentially toxic plant

• Do not panic. Rapid response is important, but panicking can interfere with the process of helping your pet.
• Immediately contact your veterinarian, emergency clinic, or an animal emergency poison control hotline.
• Safely collect any plant or substance into a sealable plastic bag. It will be helpful to your veterinarian to identify what your pet has ingested. 
• If you witness your pet consuming a plant or substance that you suspect might be toxic, don’t hesitate to seek emergency assistance, even if you do not notice any signs at the time. An animal may appear to be normal for several hours or days after the incident.
• Never induce vomiting until directed by a veterinary professional. Caustic substances will be much more dangerous coming up again.

ASPCA Animal Poison Control Center: 888-426-4435 (A consultation fee may apply)

Pet Poison Hotline: 855-764-7661 ($65 incident fee)

Disclaimer

The content of this page is not veterinary advice. This information shared here is intended for reference use only.

Sources

ASPCA – Animal Poison Control

Pet Poison Helpline

WebMD