Lobelia cardinalis
Campanulaceae
Cardinal Flower; Red Lobelia; Scarlet Lobelia; Lobelia; Indian Pink; Cardinalflower; Lobelia cardinalis
Pyridine alkaloids, primarily lobeline, with related Lobelia alkaloids including lelobines and lobinines. These compounds act in a nicotine-like fashion and may produce both stimulant and depressant effects depending on dose.
Gastrointestinal upset, diarrhea, vomiting, abdominal pain, esophageal pain, excessive salivation, drooling, excessive nasal discharge, sweating, extension of the neck, drooping of the ears, depression, loss of appetite, dilated pupils, ataxia, staggering, weakness, total exhaustion, collapse, shallow and difficult respiration, dyspnea, cardiac arrhythmias, convulsions, prolonged narcosis, partial or complete paralysis of the extremities, respiratory paralysis, cardiac arrest, coma, and death in severe cases.
Lobelia cardinalis, more commonly known as Cardinal Flower, Cardinalflower, Red Lobelia, Scarlet Lobelia, Lobelia, and Indian Pink, is an herbaceous perennial wildflower native to the Americas. The plant is found in wet soils such as marshes, stream banks, wet meadows, low woods, and other moist habitats from southeastern Canada to Minnesota, south to the Gulf of Mexico, and throughout Central America to northern Colombia.
The Cardinal Flower was so named as early as the mid-1620s for its beautiful scarlet-red flowers, whose color was similar to that of the vestures worn by Roman Catholic Cardinals of the time. A moderately tall plant, stout and erect, Cardinal Flower grows between 2 and 4 feet tall with a 1 to 2 foot spread. The alternate leaves are toothed, lanceolate to oval-shaped, pointed at both ends, and may grow up to 8 inches long and 2 inches wide.
The fire-engine-red flowers appear in long terminal racemes. Each flower has five petals united into a scarlet, two-lipped corolla. The lower lip has three very prominent lobes, while the upper lip has two smaller ones. Blooming from summer to fall, very few native flowering plants have coloration as intense as that of Cardinal Flower, which is one reason it is valued in native gardens, wetland plantings, pollinator plantings, and ornamental landscapes.
Not only beautiful, but potentially deadly when consumed in sufficient quantity, Cardinal Flower contains an array of pyridine alkaloids that act upon the body in a fashion similar to nicotine. These alkaloids are commonly divided into three groups: the lobelines, lelobines, and lobinines. In Cardinal Flower, the major alkaloid responsible for the severe symptoms of intoxication is lobeline, with the highest concentration of toxin generally associated with the summer-to-fall period when the plant produces flowers.
Lobelia species, including Lobelia cardinalis, should be treated as poisonous to cattle, sheep, goats, humans, and companion animals when eaten in quantity. The symptoms of poisoning by lobeline are much the same, though generally somewhat less pronounced, than those associated with poisoning by Nicotiana tabacum, cultivated tobacco, or Nicotiana glauca, tree tobacco.
Like nicotine, lobeline is a potent nicotinic ganglionic stimulant and may also have atropinic activity. At low doses, it may act as a stimulant. At higher doses, it may act as a severe central nervous system depressant. This dual action explains why clinical signs may begin with gastrointestinal distress, salivation, nasal discharge, weakness, or abnormal stimulation, and then progress into profound depression, shallow respiration, paralysis, collapse, convulsions, and death from respiratory failure.
Clinical signs will generally develop within one to two days of ingesting the plant, although the timing may vary depending on the amount consumed, the species of animal, the plant part involved, and whether the exposure involved one large ingestion or repeated smaller ingestions. The initial symptoms of intoxication are often diarrhea, drooling, excessive nasal discharge, vomiting, extension of the neck, and drooping of the ears.
As the disease progresses, generally over the course of hours, animals may exhibit pupillary dilation, depression, loss of appetite, total exhaustion, weakness, and collapse. As the animal’s condition worsens, cardiovascular irregularities may become apparent. Breathing may become shallow and difficult. The pulse, at first weak, may become almost imperceptible. Animals may convulse, become ataxic, and suffer partial or complete paralysis of the extremities.
In severe cases, death may occur by cardiac arrest secondary to paralysis of the respiratory muscles. Depending upon the severity of the intoxication, death may occur within hours of the initial symptoms or may be delayed for several days. In instances where an animal ingests a significant, but less than lethal amount, prolonged narcosis may occur.
In dogs and cats, fatal ingestion is less common because the plant has emetic properties and would generally cause the animal to begin vomiting shortly after ingestion. Additionally, it is unlikely that most dogs or cats could tolerate ingesting enough plant material over a short enough period of time to cause a life-threatening intoxication. However, this should not be read as making the plant safe. Any animal showing tremors, abnormal breathing, severe weakness, collapse, paralysis, convulsions, or repeated vomiting after possible Lobelia ingestion should be treated as a veterinary priority.
In horses and other grazing animals, the risk is different. They are unlikely to choose the plant as a food source unless other sources of food are unavailable, but the plant should not be allowed to grow in or around pastures, wet grazing areas, marshy fence lines, drainage ditches, stream banks, or other places where grazing animals may come into contact with it. Risk increases when desirable forage is limited, when animals are hungry, when wet areas are heavily grazed, or when toxic plant material is inadvertently mixed into hay or forage.
The primary danger in serious Lobelia poisoning is respiratory paralysis. By the time advanced clinical signs are obvious, the animal may already be in a dangerous stage of intoxication. This is why witnessed ingestion should be handled promptly, and why animals with respiratory distress, shallow breathing, weakness, collapse, paralysis, convulsions, or cardiac irregularity require immediate veterinary intervention.
Immediate Response to Cardinal Flower Ingestion
- Remove the Source: Prevent further ingestion by removing the animal from the plant, wetland edge, stream bank, garden planting, pasture margin, hay, forage, or any area containing Cardinal Flower or other Lobelia species.
- Remove Plant Material from the Mouth: If the animal is witnessed eating the plant, or if identifiable plant matter is found in the mouth, remove visible plant material and flush the mouth thoroughly with water.
- Identify the Exposure: Determine whether the animal consumed leaves, stems, flowers, roots, dried material, hay-contaminating material, or an unknown amount. Also determine whether the exposure involved a single witnessed ingestion or repeated grazing over time.
- Do Not Wait for Advanced Signs: Serious Lobelia poisoning can progress to respiratory paralysis, weakness, collapse, convulsions, cardiac irregularity, and death. Any suspected significant ingestion should be taken seriously before severe signs develop.
- Watch for Early Signs: Monitor for drooling, excessive nasal discharge, vomiting, diarrhea, neck extension, drooping ears, loss of appetite, depression, weakness, shallow breathing, or abnormal behavior.
- Contact Veterinary Help Promptly: Consult a veterinarian, emergency veterinary clinic, Pet Poison Helpline, or another animal poison-control professional if ingestion is suspected, if the amount is unknown, if symptoms are present, or if the exposed animal is a dog, cat, horse, cow, sheep, goat, young animal, elderly animal, pregnant animal, or medically fragile animal.
Inducing Vomiting and Decontamination
- Getting Plant Material Out Matters: If a dog has recently swallowed Cardinal Flower or another Lobelia species, removing remaining plant material from the stomach may reduce continued exposure to lobeline and related alkaloids. In appropriate dog exposures, vomiting may be one of the least disruptive ways to remove recently ingested plant material before more toxin is absorbed.
- Inducing Vomiting in Dogs Only: If ingestion was recent and the dog is alert, breathing normally, able to swallow, and not showing weakness, collapse, shallow breathing, repeated vomiting, tremors, convulsions, severe depression, paralysis, respiratory distress, cardiac irregularity, or neurologic signs, a veterinarian or animal poison-control professional may recommend inducing vomiting with fresh 3% hydrogen peroxide.
- Cat Warning: Hydrogen peroxide should not be used to induce vomiting in cats unless a veterinarian specifically directs it. Cats are more prone to irritation and complications from hydrogen peroxide, and home vomiting attempts may create more risk than benefit.
- Do Not Induce Vomiting in an Unstable Animal: Vomiting should not be attempted in any animal that is weak, collapsed, sedated, having trouble breathing, unable to swallow normally, already vomiting repeatedly, showing neurologic signs, showing paralysis, or otherwise unstable.
- Activated Charcoal: Activated medical charcoal is a valuable tool for adsorbing ingested lobeline in the stomach and intestinal tract, but it should be administered under veterinary or poison-control direction, especially if the animal is depressed, vomiting, weak, or at risk of aspiration.
- Gastric Lavage: In acute toxicity, where a large amount may have been ingested or where the animal is already under veterinary care, gastric lavage may be performed to help remove remaining plant material and toxin from the stomach.
Respiratory and Emergency Support
- No Definitive Antidote: There is no definitive antidote for lobeline poisoning, as lobeline acts upon the body in a manner similar to nicotine. Treatment is largely symptomatic and supportive.
- Respiratory Support is Critical: The primary cause of death in serious lobeline poisoning is respiratory paralysis, so the emphasis of treatment is respiratory support and maintenance of breathing.
- Artificial Respiration: In severe cases, artificial respiration may be needed to keep the patient breathing and alive until the toxin can be metabolized, eliminated, or reduced to non-toxic concentrations.
- Shock Prevention: Following decontamination or lavage, the patient should be kept calm and warm to help reduce the risk of shock.
- Oxygen and Intensive Care: Animals with shallow breathing, dyspnea, collapse, weakness, paralysis, or convulsions may require oxygen therapy, intubation, assisted ventilation, and intensive veterinary monitoring.
Veterinary Treatment and Monitoring
- Minor Ingestion: In many cases of minor ingestion, especially when the ingestion is witnessed and treatment occurs promptly, the pet may make a full recovery in a matter of hours.
- Large or Repeated Ingestion: In cases of acute toxicity where a large amount of the plant may have been ingested, or where smaller amounts were consumed over a number of days and advanced clinical signs are beginning to manifest, aggressive respiratory support and treatment of shock are important countermeasures.
- Tannic Acid: Tannic acid solution may prove useful in precipitating this alkaloid under veterinary direction.
- Avoid Alkaline Solutions: Alkaline solutions, which may facilitate absorption, should be avoided.
- Potassium Permanganate Lavage: Diluted potassium permanganate solution in lavage fluid may be used by a veterinarian to dilute or oxidize lobeline in severe poisoning cases.
- Autonomic Signs: Symptoms of parasympathetic or sympathetic hyperactivity may be controlled with atropine and phentolamine given intravenously or intramuscularly under veterinary supervision.
- Cardiac Arrhythmias: Cardiac arrhythmias may be treated with propranolol or other veterinary-directed medication when clinically appropriate.
- Convulsions: Patients exhibiting convulsions may require sedation, such as intravenous diazepam, along with additional supportive care.
- Hypotension: Vasopressor drugs may be required if hypotension fails to respond to usual therapy.
Livestock, Pasture, and Field Management
- Pasture Control: Cardinal Flower and other Lobelia species should not be allowed to grow in or around pastures, wet grazing areas, drainage ditches, marshy fence lines, stream banks, or areas where grazing animals are likely to encounter them.
- Forage Availability: Horses, cattle, sheep, and goats are less likely to choose the plant when adequate forage is available, but risk increases when other food sources are scarce.
- Inspect Wet Areas: Marshes, wet ground, ditches, stream edges, low woods, and poorly drained pasture margins should be inspected for Lobelia growth where grazing animals have access.
- Hay and Forage: Hay, forage, or cut vegetation should be inspected if contamination with Lobelia is suspected.
Prognosis and Recovery
- Prompt Treatment: The prognosis with prompt treatment is considered good when the animal is witnessed eating a plant of the Lobelia genus, the exposure is stopped, and treatment is instituted before advanced signs develop.
- Delayed Recognition: Unfortunately, most animals that ingest a potentially lethal dose of lobeline may go unnoticed until clinical signs develop, and in severe cases the time between onset of symptoms and death may be only a few hours.
- Severe Cases: Prognosis is guarded to poor when respiratory paralysis, convulsions, collapse, partial or complete paralysis, cardiac arrest, or severe respiratory distress develops.
- Prolonged Narcosis: Animals that ingest a significant but less-than-lethal amount may experience prolonged narcosis and require careful monitoring until normal respiration, strength, and mentation return.
- Prevention: Prevent further ingestion of the plant, remove access to Lobelia species, and contact a veterinarian promptly whenever exposure is suspected.