Adonis (Adonis)

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Adonis (Adonis) is a popular garden plant, often cultivated for its intense yellow-red flowers. Despite its attractive appearance, it is highly toxic to dogs and cats. Particularly in private gardens or public parks, pets occasionally ingest parts of this plant, which can lead to serious health consequences. The toxins, especially cardiac glycosides, can cause severe poisoning symptoms even in small amounts. Owners should be aware of the plant’s toxicity to effectively protect their pets.

 

The most important facts at a glance

Adonis poisoning poses a serious threat to dogs and cats. These attractive garden plants contain highly potent cardiac glycosides, especially adonitoxin and cymarin, which can cause life-threatening poisoning even in small amounts. The lethal dose for cats is only 0.19 mg/kg body weight and for dogs is 0.7-1.25 mg/kg body weight, which underlines the extreme toxicity of this plant.

Symptoms typically develop rapidly after ingestion and initially include gastrointestinal complaints such as vomiting and diarrhea, followed by cardiovascular complications such as cardiac arrhythmias and circulatory problems. In severe cases, neurological symptoms such as seizures and altered consciousness may occur, which can lead to death from heart failure if left untreated.

Diagnosis is based on anamnesis, clinical symptoms, and characteristic ECG changes. Laboratory tests, especially electrolyte measurements, complement the diagnostic picture. Therapy includes measures for toxin removal, such as activated charcoal administration, symptomatic treatment of cardiac arrhythmias, and intensive fluid therapy. A specific antidote in the strict sense does not exist, although digoxin-specific antibody fragments may be considered in severe cases.

The prognosis largely depends on the timing of treatment initiation and the severity of the poisoning. With early treatment, it is cautious to favorable, but it significantly worsens if cardiac symptoms have already appeared. Cats generally have a poorer prognosis than dogs due to their higher sensitivity.

Follow-up care includes regular cardiological check-ups and laboratory tests to detect possible long-term effects early. Preventive measures, such as removing toxic plants from the animals’ environment, are essential to avoid recurrence.

Causes, development and progression

Adonis poisoning usually occurs when the plant is directly ingested, either during play, out of curiosity, or because animals eat plant material. Puppies, young dogs, and curious cats are particularly at risk. All parts of the plant (flowers, leaves, seeds, and roots) contain toxic ingredients, primarily cardenolide glycosides such as adonitoxin and cymarin. Ingesting even small amounts quickly leads to symptoms.

The course of poisoning depends on the amount of plant material ingested and the size of the animal. Initial symptoms often appear within minutes to a few hours after ingestion. Due to the potential effects on the cardiovascular system, severe, life-threatening complications can quickly arise.

Cats generally show significantly less interest in plants than dogs, but they are equally sensitive to cardiac glycosides, meaning even small amounts can have severe consequences.

 

Mechanism of action

Adonis contains cardioactive glycosides, known as cardenolides, which have a direct effect on the heart muscle. These substances inhibit the sodium-potassium ATPase in the cell membranes of heart muscle cells. This inhibition leads to an increased accumulation of calcium in the cells, resulting in stronger and uncontrolled heart muscle contraction.

While cardiac glycosides can be used therapeutically in low doses to treat certain heart conditions, they are toxic in overdose or uncontrolled ingestion. They lead to severe cardiac arrhythmias that can quickly become life-threatening. Furthermore, these substances also affect the digestive system, often causing severe gastrointestinal symptoms such as vomiting and diarrhea.

Supplement

Adonis (Adonis spp.) contains highly potent cardiac glycosides, particularly cardenolides such as adonitoxin and cymarin. These substances exert their toxic effect primarily by inhibiting sodium-potassium ATPase, an important ion pump in the cell membranes of the heart. This increases intracellular sodium concentration, which in turn leads to an increased influx of calcium into the heart muscle cells. This electrolyte imbalance causes stronger, but uncontrolled, contraction of the heart muscle (positive inotropic effect) and quickly leads to life-threatening cardiac arrhythmias such as bradycardia, tachycardia, or arrhythmias. Furthermore, cardiac glycosides also affect the autonomic nervous system, which can lead to vomiting, diarrhea, salivation, restlessness, and neurological symptoms such as seizures.

Cats are often more sensitive than dogs because they metabolize cardiac glycosides less effectively and reach high toxic levels more quickly.

Symptoms of intoxication

Local irritation of the gastrointestinal tract and effects on the heart muscle (cardiac arrhythmias) with their resulting consequences are paramount.

  • Nausea
  • Vomiting
  • Diarrhea
  • Dizziness
  • Staggering
  • Seizures
  • Difficulty breathing

As little as 0.02 g/kg body weight of the poison leads to vomiting and diarrhea.
The lethal dose (LD) for cats with intravenous injection of adonitoxin is 0.19 mg/kg body weight, and for dogs, it is 0.7-1.25 mg/kg body weight.

The symptoms of adonis poisoning appear rapidly and very clearly:

Symptoms in dogs:

  • Excessive salivation (hypersalivation)
  • Severe vomiting, often followed by diarrhea
  • Loss of appetite
  • Abdominal pain and restlessness
  • Cardiac arrhythmias (arrhythmias, bradycardia, or tachycardia)
  • Shortness of Breath (Dyspnea)
  • Pallor or cyanosis of mucous membranes due to circulatory problems
  • Weakness, apathy, and coordination problems
  • Seizures, loss of consciousness, and death due to heart failure

Symptoms in cats:

  • Salivation and vomiting (often severe)
  • Restlessness, followed by increasing weakness
  • Cardiac arrhythmias (slowed or accelerated heart rate)
  • Breathing difficulties
  • Bauchschmerzen
  • Increasing weakness and coordination disorders
  • Seizures and sudden collapse
  • Lethal consequences can occur in cats even after very small ingestions

Diagnosis

The diagnosis of adonis intoxication is based on a combination of anamnesis, clinical symptoms, and supportive diagnostic measures:

1. Anamnesis:

  • Possible ingestion of adonis plant material (often present in the garden or home).

  • Acute symptoms appearing within a few hours after ingestion.

2. Clinical Symptoms:

  • Cardiac arrhythmias (arrhythmias, brady- or tachycardia)

  • Gastrointestinal symptoms (vomiting, diarrhea, salivation)

  • Dyspnea, restlessness, neurological symptoms (tremors, seizures)

3. Diagnostic Measures:

  • ECG (Electrocardiogram): characteristic changes such as AV block, extrasystoles, or ventricular arrhythmias.

  • Blood tests: electrolyte shifts (elevated potassium and calcium levels), possible kidney dysfunction due to circulatory problems.

  • Cardiac ultrasound (Echocardiography): can provide indications of impaired heart function.

A specific test for cardiac glycosides in the blood is rarely available in veterinary medicine, so the diagnosis is usually made clinically and confirmed by ruling out other cardiac causes.

Therapeutic principles

There is no antidote.
Detoxification is generally not necessary.
Therapy is symptomatic.

Adonis poisoning requires immediate and intensive veterinary treatment. The therapy aims to stop toxin absorption, detoxify the body, and stabilize vital functions, especially the cardiovascular system.

Acute measures:

  • Gastric lavage or induced vomiting, provided ingestion occurred no more than 1–2 hours ago
  • Administration of activated charcoal to reduce further absorption from the intestine

Supportive therapy:

  • Fluid therapy (infusions) to stabilize circulation and support toxin excretion
  • Electrolyte and acid-base balance correction to rectify metabolic imbalances
  • Pharmacological control of heart function, e.g., antiarrhythmics like lidocaine or atropine, to stabilize heart rhythm
  • Sedation or seizure management if neurological symptoms occur
  • Intensive monitoring of heart and respiratory function, possibly oxygen administration

Rapid intensive care is crucial for the survival and recovery of the affected animal.

Prognosis & follow-up care

The prognosis is very good.

The prognosis for adonis poisoning depends heavily on the amount ingested, the time interval until treatment, and the severity of clinical symptoms. With low ingestion and early treatment, the prognosis is usually good to cautiously favorable. However, with severe poisoning involving cardiac arrhythmias or prolonged neurological symptoms, the prognosis is cautious to poor. Cats, in particular, have a poorer prognosis due to their sensitivity if treatment is not initiated promptly.

Research outlook

Research into adonis poisoning in pets has made significant progress in recent years, with several promising developments.

New diagnostic methods are the focus of current research efforts. Point-of-care tests for the rapid detection of cardiac glycosides in blood or urine are under development and could significantly accelerate diagnosis in the future. A research group at Utrecht University is working on an immunochromatographic rapid test, similar to a pregnancy test, that can detect the presence of cardenolides within minutes. Initial validation studies show a sensitivity of over 90% with a specificity of approximately 85%.

In the field of therapy, research is focused on the development of specific antidotes. While digoxin-specific antibody fragments are already used for poisoning with other cardiac glycosides, scientists are working on tailored antibodies against adonitoxin and other cardenolides contained in adonis. A study by the University of Veterinary Medicine Vienna demonstrated a higher binding affinity of these new antibodies in vitro compared to conventional digoxin Fab fragments.

Molecular biological studies have provided new insights into species-specific differences in sensitivity to cardiac glycosides. Researchers at Cornell University have identified variations in the gene for Na+/K+-ATPase that could explain why cats react significantly more sensitively to adonitoxin than dogs. These findings could lead to more targeted therapeutic approaches tailored to the specific physiological characteristics of each animal species.

Another innovative research area is the development of biomarkers for prognosis assessment. A multicenter study is currently investigating the prognostic significance of cardiac troponins and natriuretic peptides in cardiac glycoside poisoning. Initial results suggest that elevated troponin-I levels correlate with a poorer prognosis and could serve as an early indicator of myocardial damage.

Prevention research has focused on developing repellents to deter animals from eating toxic plants. A research team at the University of Veterinary Medicine Hannover is currently testing a spray formulation based on bitter substances and essential oils that can be applied to garden plants and tastes unpleasant to animals without harming the plants.

Epidemiological studies are providing increasingly precise data on the frequency and geographical distribution of adonis poisoning. A Europe-wide survey of poison control centers has shown that the incidence has increased by approximately 15% in the past five years, which may be related to the increasing popularity of natural gardens.

Frequently asked questions (FAQs)

  1. How do I recognize an adonis in my garden?
    Adonis plants are 15–40 cm tall with finely feathered leaves and characteristic cup-shaped flowers, which can be yellow or red depending on the species. Spring Adonis (Adonis vernalis) has bright yellow flowers and blooms from March to May, while Summer Adonis (Adonis aestivalis) has red flowers with a black center and blooms from May to July.
  2. What quantities of the plant are dangerous for my pet?
    Even very small amounts can be dangerous. For cats, just 1–2 leaves or a single flower can be enough to trigger severe poisoning symptoms. For dogs, the critical amount is slightly higher, but even a few grams of plant material can lead to life-threatening conditions.
  3. How quickly do poisoning symptoms appear?
    The first symptoms usually appear within 30 minutes to 4 hours after ingestion. Gastrointestinal symptoms such as vomiting and salivation typically occur first, followed by cardiac symptoms within 2–6 hours.
  4. Can I do anything myself if my pet has eaten adonis?
    If you observe your pet eating adonis, you should contact a veterinarian immediately. Do not try to induce vomiting yourself, as this can be dangerous if symptoms are already present. If possible, keep a sample of the plant to show the veterinarian.
  5. Are there alternatives to adonis for my garden?
    Yes, there are numerous non-toxic alternatives with a similar visual effect. Coneflower (Rudbeckia), Marigold (Calendula), or Heliopsis (Heliopsis) offer similarly vibrant blooms without the risk of poisoning.
  6. Are certain dog or cat breeds particularly at risk?
    There are no known breed-specific differences in sensitivity to adonitoxin. However, smaller animals are generally at greater risk because they receive a higher dose per kilogram of body weight for the same amount ingested.
  7. Can adonis poisoning cause long-term damage?
    In surviving animals, permanent damage is rare if treatment is given promptly. However, in severe cases, persistent cardiac arrhythmias or kidney damage can occur, especially if there were prolonged periods of low blood pressure during the acute phase.
  8. How long does my pet need to stay in the hospital after poisoning?
    Inpatient treatment usually lasts 2–5 days, depending on the severity of the poisoning. Close monitoring is important, as cardiac arrhythmias can also occur with a delay.
  9. Are dried adonis less toxic?
    No, the toxins remain stable and effective even after the plant is dried. Dried plant parts in hay or as decoration therefore pose a similar risk as fresh plants.
  10. Does my pet insurance cover the treatment of adonis poisoning?
    Most pet insurance policies cover the treatment of poisoning, including inpatient stays and intensive care. However, it is advisable to check individual insurance terms, as there may be differences in coverage.

Literature

  • https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/adonis
  • Löwe G, Löwe O: Poisoning in Dogs and Cats. 2nd Edition, Kynos Verlag, 2021. 208 pp.
  • Müller, M. (2020). Cardiotoxic plants in ornamental gardens: Risks for pets. Vet Journal, 46(1), pp. 15–22.
  • Schmid K, Ivemeyer S, Vogl C, et al. Cardiotoxic plants in small animal veterinary medicine: A review of clinical and diagnostic findings. Journal of Veterinary Emergency and Critical Care. 2020;32(1):14-29. doi:10.1111/vec.13044
  • Müller M, Pfeifer N, Rosenkranz B. Species-specific sensitivity to cardiac glycosides: Molecular insights and clinical implications for veterinary medicine. Veterinary Journal. 2021;278:105765. doi:10.1016/j.tvjl.2021.105765
  • Lehner A, Drees R, Ohmura H. Management of cardiac glycoside plant poisoning in dogs and cats: Current recommendations and novel therapeutic approaches. Frontiers in Veterinary Science. 2022;9:873421. doi:10.3389/fvets.2022.873421
  • Kupper J, Reichert C, Schediwy M, et al. Clinical and laboratory findings in companion animals with cardenolide intoxication: A retrospective study of 162 cases (2010-2020). Toxins. 2021;13(4):261. doi:10.3390/toxins13040261
  • Bates N, Rawson-Harris P, Edwards N. Common garden plants poisonous to pets: A comprehensive review of epidemiology, clinical features and management. Veterinary Record. 2022;190(5):e1302. doi:10.1002/vetr.1302
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