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Milkweed
Asclepias spp.
Milkweed (Asclepias spp.) is a toxic plant for cats due to cardenolide cardiac glycosides — potent compounds found throughout the plant, with the highest concentration in the milky latex sap. These compounds act on the heart in a manner similar to Foxglove, disrupting the electrical signals that regulate heartbeat. All parts including dried plant material remain toxic.
Important Notes
Toxic compounds: cardenolide cardiac glycosides in latex sap, leaves, and stems
Mechanism: cardenolides inhibit the Na+/K+-ATPase pump in cardiac muscle cells, causing arrhythmias
Symptoms: drooling, vomiting, weakness, abnormal heart rate, muscle tremors; severe cases may cause seizures and cardiac failure
The milky latex sap is the most concentrated source — avoid contact with broken stems
Seek veterinary care promptly; cardiac glycoside toxicity can escalate rapidly
Potentially Toxic Parts
Sap
All parts of the plant
Possible Symptoms Reported in Cats
Abnormal heart rates and rhythms (including bradycardia, tachycardia, and severe arrhythmias)
Cardiac · Within 2 hours
Vomiting and diarrhea
Gastrointestinal · Within 2 hours
Weakness and unspecified neurological signs
Neurological · Within 2 hours
Breathing difficulties (dyspnea)
Respiratory · Within 2 hours (or developing as the condition worsens).
Organ damage
Renal · Delayed (typically develops as symptoms persist over 4–5 days).
Disclaimer: This summary was compiled from multiple sources and is for informational use only. It is not a diagnosis or treatment plan. Toxicity can vary based on the substance, amount, plant part, and individual cat. If you think your cat may have been exposed to a toxic substance, contact a veterinarian right away.