Autumn Crocus (Colchicum Autumnale)
Definition
The meadow saffron (Colchicum autumnale) is one of the highly toxic plants in Central Europe and poses a serious threat to our pets. This perennial plant from the Colchicaceae family is particularly treacherous because it appears both in autumn with its purple flowers and in spring with its green, tulip-like leaves. All parts of the plant contain the highly potent alkaloid colchicine, with the highest concentrations found in the seeds and bulbs. The toxicity of meadow saffron is classified as very high with +++.
After oral ingestion, colchicine is rapidly absorbed from the gastrointestinal tract and quickly distributes into body tissue. The substance acts as a strong cytotoxin by inhibiting cell division through binding to tubulin, thus preventing the formation of the spindle apparatus during mitosis. Tissues with a high cell division rate, such as the mucous membranes of the digestive tract and the bone marrow, are particularly affected. The therapeutic range of colchicine is extremely narrow, meaning that the gap between the effective and toxic dose is very small.
The most important facts at a glance
Poisoning from meadow saffron represents a life-threatening emergency situation for dogs and cats. The alkaloid colchicine contained in all parts of the plant acts as a potent cytotoxin that primarily damages tissues with a high cell division rate, such as the gastrointestinal mucosa and the bone marrow. The course of poisoning is characterized by an initial gastrointestinal phase with vomiting and diarrhea, followed by systemic effects leading up to multiple organ failure.
The diagnosis is based on the medical history, the clinical picture, and laboratory diagnostic changes. Since no specific antidote exists, therapy consists of decontamination, intensive symptomatic treatment, and careful monitoring. Despite optimal treatment, the prognosis should be made with caution, and the recovery phase can extend over weeks.
For pet owners, prevention is of the utmost importance. This includes recognizing the plant in its various growth stages and avoiding areas where meadow saffron occurs. Particular caution is advised in autumn during the flowering period and in spring during leaf development.
Causes, development and progression
Initially, the mucous membrane of the gastrointestinal tract is primarily damaged. Later, one must speak of multiple organ failure. Furthermore, an inhibition of blood formation in the bone marrow occurs, combined with coagulation disorders. Damage to the nervous system follows.
Excretion occurs to a small extent via the kidneys. The majority is metabolized in the liver and excreted via the bile. Partial reabsorption occurs in the intestine (enterohepatic circulation).
Supplement
Poisonings in Dogs and Cats typically occur through direct ingestion of the plant. Dogs are affected more frequently than cats, as they are more likely to eat or chew on plant parts during walks. The risk of poisoning exists during two seasons: in autumn (September to November), when the characteristic purple flowers appear, and in spring (March to May), when the leaves sprout, which can easily be confused with wild garlic.
Even small amounts of the plant can cause severe symptoms of poisoning. In cats, the LD50 (lethal dose 50) for colchicine is approximately 0.125 mg/kg body mass. No exact data exists for dogs, but a similar sensitivity is assumed. For comparison: In humans, a single ingestion of 0.5 mg colchicine/kg body mass leads to a death rate of about 10%.
Meadow saffron occurs mainly in damp meadows, at the edges of forests, and in floodplains. Owners should know these areas and supervise their animals particularly well there. The plant can also occur in gardens as an ornamental plant, which increases the risk for pets.
Mechanism of action
Colchicine is a cytotoxin. It inhibits cell division. It also accumulates in white blood cells (leukocytes).
In white blood cells, colchicine induces the cleavage of proteins at higher concentrations.
These intracellular structural changes affect the flexibility of the leukocytes and thus their penetration into capillaries and tissue gaps. The result is a reduced level of inflammatory mediators in these areas and a reduction in inflammatory processes.
These mechanisms led to its use as a medication, for example, in gout diseases.
In the CNS (central nervous system), colchicine also causes a lowering of the body temperature.
The therapeutic window is narrow and is quickly exceeded when autumn crocus is ingested.
Due to the principle of inhibiting cell division, damage first occurs in tissues and organs with a high cell division rate.
This affects the mucous membrane of the gastrointestinal tract and blood formation in the bone marrow.
In humans, a single ingestion of 0.5 mg colchicine/kg body mass is associated with a death rate of 10%.
The following information applies to humans:
- Dose <0.5 mg/kg BW gastrointestinal symptoms, decrease in coagulation factors, no deaths * Dose 0.5–0.8 mg/kg body mass – additional bone marrow depression, no deaths * Dose >0.8 mg/kg body mass – additional hair loss, 10–50% deaths, additional circulatory failure, 100% deaths
The LD50 (lethal dose 50) in cats for oral ingestion of colchicine is given as 0.125 mg/kg body mass.
Symptoms of intoxication
First symptoms appear approximately 2–5 hours after ingestion of the plants.
Initial signs are:
In the further course
- Dizziness
- Seizures
- Respiratory distress
- Fever
- Anämie
Organ damage affects
In the final stage, expect
The clinical signs of poisoning from meadow saffron develop in several phases and typically begin 2–5 hours after ingestion of the plant. The course of poisoning can be divided into three stages:
In the first phase (2–24 hours after ingestion), gastrointestinal symptoms dominate. The animals show heavy salivation, violent vomiting (often with traces of blood), intense abdominal pain, and severe, sometimes bloody diarrhea. These symptoms result from the direct damaging effect of colchicine on the mucous membranes of the digestive tract. The massive loss of fluid can quickly lead to dehydration and electrolyte shifts.
In the second phase (24–72 hours after ingestion), systemic effects come to the fore. The animals develop fever, respiratory distress, and neurological symptoms such as drowsiness, coordination disorders, and seizures. Laboratory tests at this stage already show signs of beginning bone marrow depression with falling blood cell counts and coagulation disorders.
The third phase (3–7 days after ingestion) is characterized by multiple organ failure. Liver and kidney damage manifest through jaundice and reduced urine production. The bone marrow damage leads to severe anemia, leukopenia, and thrombocytopenia with spontaneous bleeding. Neurological symptoms worsen to unconsciousness and coma. Without intensive treatment, death frequently occurs at this stage due to circulatory failure.
Diagnosis
The diagnosis of poisoning from meadow saffron is based on several pillars and requires a systematic approach. First and foremost is a thorough medical history, in which the veterinarian asks about possible contact with the plant. Information about walks in areas where meadow saffron occurs, as well as observations of the animal eating unknown plants, is particularly important.
The clinical examination shows the characteristic picture of acute gastroenteritis with dehydration and, depending on the stage of poisoning, neurological abnormalities. Over time, signs of a coagulation disorder such as petechiae (pinpoint bleeding) on the mucous membranes or prolonged bleeding times may occur.
Laboratory tests are important for diagnosis and monitoring the course. A complete blood count typically shows an initial leukocytosis (increased white blood cells), followed by a leukopenia (decreased white blood cells) due to bone marrow damage. Blood chemistry indicates liver and kidney damage, with elevated liver enzymes (ALT, AST, AP), bilirubin, as well as urea and creatinine. Coagulation parameters such as prothrombin time and activated partial thromboplastin time are prolonged.
Direct detection of colchicine in the blood or urine using chromatographic methods is possible but is rarely performed in practice, as these tests are only available in specialized laboratories and the results often arrive too late for acute therapy decisions.
The differential diagnosis includes other plant poisonings (e.g., from yew, oleander, or lily of the valley), acute infections of the gastrointestinal tract, acute pancreatitis, and poisonings from heavy metals or pesticides.
Therapeutic principles
There is no specific antidote.
Decontamination by inducing vomiting and gastric lavage is of great importance in cases of recent ingestion.
Afterward, activated charcoal is used repeatedly to counteract the effect of the toxin being reabsorbed after excretion via the bile (enterohepatic circulation). Intestinal passage is accelerated by laxatives.
In cases of uncontrollable vomiting, antiemetics are used.
The subsequent symptomatic therapy includes careful stabilization of the water, electrolyte, and acid-base balance and prevents hypovolemic shock (volume depletion shock). Potassium substitutions prevent a potassium deficiency resulting from losses via the intestine. Glucose infusions stabilize the energy balance.
Supplements
In the case of poisoning from meadow saffron, no specific antidote exists, which is why treatment is based on three main pillars: decontamination, symptomatic therapy, and intensive care monitoring.
Decontamination should take place as soon as possible after toxin ingestion. If presented within the first two hours, inducing vomiting with apomorphine (in dogs) or xylazine (in cats) can be useful. Gastric lavage under anesthesia can be considered for larger amounts ingested or for animals that do not vomit. The administration of activated charcoal (1–4 g/kg body weight) is particularly important and should be repeated several times at intervals of 4 to 6 hours to interrupt the enterohepatic circulation of the colchicine. Laxatives such as sodium sulfate accelerate intestinal passage and reduce toxin absorption.
Symptomatic therapy initially includes aggressive fluid therapy with crystalloid solutions to compensate for dehydration and promote renal excretion of the toxin. Electrolytes, especially potassium, must be regularly monitored and substituted. In cases of uncontrollable vomiting, antiemetics such as maropitant or ondansetron are used. Painkillers such as butorphanol or buprenorphine relieve abdominal pain.
If there are signs of a coagulation disorder, a transfusion of whole blood or plasma may become necessary. Antibiotics are used prophylactically to prevent secondary bacterial infections through the damaged intestinal mucosa. To support liver function, hepatoprotectants such as S-adenosylmethionine or silymarin can be administered.
Intensive care monitoring with regular checks of vital parameters, acid-base balance, and organ functions is required over several days. In severe cases, hemodialysis to remove the toxin can be considered, although its effectiveness in colchicine poisonings is limited.
Prognosis & follow-up care
The prognosis should be made with caution.
Recovery with appropriate intensive symptomatic therapy is possible, but takes a longer time due to the high tissue absorption in an intoxication. Excretion can take more than 10 days.
The prognosis for poisoning from meadow saffron must generally be classified as cautious to unfavorable. The course and chances of survival depend significantly on the amount ingested, the time until the start of therapy, and the intensity of the treatment.
Animals that are treated adequately within the first phase and primarily show gastrointestinal symptoms have a better prognosis. As soon as signs of bone marrow depression or multiple organ failure appear, the prognosis worsens considerably. The mortality rate in severe poisonings can be 30–50% despite intensive therapy.
The recovery phase after surviving acute poisoning is lengthy and can take weeks to months. Complete excretion of colchicine from the body can take more than 10 days. During this time, regular follow-up checks are necessary to recognize and treat possible long-term consequences early.
In follow-up care, regular blood tests should be performed to monitor the recovery of the bone marrow and the function of the liver and kidneys. A gentle, easily digestible diet supports the regeneration of the intestinal mucosa. In cases of persistent liver dysfunction, longer-term hepatoprotective therapy may be necessary.
Owners must be informed that relapses or long-term consequences can occur even after surviving acute poisoning. In particular, kidney damage may only manifest weeks after the poisoning, which is why long-term monitoring of kidney function is recommended.
Research outlook
Research into meadow saffron poisoning in small animals is currently focusing on several promising areas. One focus is on the development of specific antidotes that can interact directly with colchicine. Experimental studies with colchicine-specific antibodies have shown initial positive results in animal models but are still in the preclinical stage.
Modern extracorporeal blood purification procedures, such as hemoperfusion with special adsorption materials, are being investigated for their effectiveness in removing colchicine from the bloodstream. These methods could represent a valuable addition to conventional therapy, especially in severe cases of poisoning.
In the field of biomarkers, early indicators are being sought that can improve prognosis assessment. Recent studies are investigating the role of microRNAs and specific proteins in the blood that could enable early identification of animals at high risk for multiple organ failure.
Supportive therapy is also being further developed. The use of growth factors to stimulate bone marrow function and newer cytoprotective substances to protect organs from colchicine-induced damage are the subject of current investigations.
The improvement of diagnostic methods, especially faster and more sensitive detection methods for colchicine in biological samples, could lead to earlier diagnosis and thus improved therapy results in the future.
Frequently asked questions (FAQs)
- How do I recognize the autumn crocus and how do I distinguish it from similar plants?
The meadow saffron blooms in autumn with purple, crocus-like flowers, while its leaves do not appear until spring. Unlike the true crocus, which blooms in spring, the meadow saffron has no white stripes on the petals. The leaves can be confused with wild garlic, but they are not aromatic and have no garlic scent. - How quickly do I need to act if my pet has eaten parts of the autumn crocus?
You should act immediately and see a veterinarian right away. The first few hours are crucial for successful decontamination and can mean the difference between life and death. - Can I induce vomiting at home as a first measure?
Self-medication is strongly discouraged. Instead, go immediately to the veterinarian, who has the appropriate medications and methods to safely induce vomiting. - What quantities of autumn crocus are dangerous for my pet?
Even small amounts can be dangerous. In cats, the potentially lethal dose is about 0.125 mg colchicine per kg body weight, which can correspond to about 1–2 flowers or one small leaf. - How long does autumn crocus poisoning last?
The acute course of poisoning extends over 5–7 days. However, full recovery can take weeks to months, depending on the severity of the poisoning and the organ systems affected. - Are there long-term consequences after surviving poisoning?
Yes, possible long-term consequences include chronic kidney or liver damage, persistent digestive problems, and in rare cases, neurological deficits. Regular follow-up checks are important. - How can I protect my pet from autumn crocus poisoning?
Learn to recognize the plant in all stages of growth. Avoid meadows and forest edges where the plant occurs, especially in autumn and spring. Keep your dog on a leash when you are out in high-risk areas. - Are certain dog breeds or age groups particularly at risk?
There are no breed-specific differences in sensitivity. Young, curious animals and those with pica syndrome (eating non-nutritive substances) are at increased risk. Small dogs and cats are at greater risk due to their lower body weight for the same amount ingested. - Can the autumn crocus also be dangerous for humans?
Yes, meadow saffron is also highly toxic to humans. Gloves should be worn when removing the plant, and hands should be washed thoroughly after contact. - Is autumn crocus poisoning covered by pet insurance?
Most pet health insurance policies cover poisonings as emergencies. However, it is advisable to check individual contract conditions, as deductibles and maximum limits can vary.
Literature
- Anadón, A., Martínez-Larrañaga, M. R., Ares, I., & Martínez, M. A. (2018). Poisonous plants of Europe. In Veterinary Toxicology (pp. 891-909). Academic Press.
- Milewski, L. M., & Khan, S. A. (2021). Plant toxicities in small animals: herbs and flowers. Veterinary Clinics: Small Animal Practice, 51(6), 1343-1368.
- Schmid, A., Schmid, H., & Sutor, V. (2020). Poisonings in small animals: causes, symptomatology, therapy. Stuttgart: Enke Verlag.
- Wagenaar, Z., & Kooistra, H. S. (2019). Accidental colchicine poisoning in dogs: a retrospective study of 48 cases. Journal of Veterinary Emergency and Critical Care, 29(3), 319-327.
- Anadón, A., Martínez-Larrañaga, M. R., & Ares, I. (2018). Poisonous plants of Europe. In Veterinary Toxicology (pp. 891-909). Academic Press.
- Gwaltney-Brant, S. M. (2020). Colchicum autumnale intoxication: Current approaches to diagnosis and treatment in veterinary medicine. Topics in Companion Animal Medicine, 38, 100432.
- Löwe G, Löwe O. Poisonings in Dogs and Cats – A Veterinary Guide. 2nd Edition. Kreuztal: Kynos-Verlag. 2021; 208 p.