Milkweed

Symptoms reported in cats

Most serious first.

1. 1
   Abnormal heart rate and rhythm (bradycardia, tachycardia, arrhythmias) Within 2 hours · This is the most dangerous effect of the plant's cardiac glycosides, which disrupt the Na+/K+ ATPase pump and alter how the heart muscle contracts. This can also trigger hyperkalemia (dangerously high potassium levels in the blood), which is life-threatening.
2. 2
   Vomiting and diarrhea Within 2 hours · These are generally the first visible signs of cardiac glycoside toxicosis before systemic cardiovascular symptoms become apparent.
3. 3
   Weakness and unspecified neurological signs Within 2 hours · These symptoms manifest as the cardiovascular system becomes profoundly depressed and cellular oxygen/energy cycles are disrupted.
4. 4
   Breathing difficulties (dyspnea) Within 2 hours (or developing as the condition worsens). · Respiratory distress frequently occurs secondarily as the heart begins to fail and blood pressure drops.
5. 5
   Organ damage Delayed (typically develops as symptoms persist over 4–5 days). · Depending heavily on the amount of milkweed or toxic sap ingested, systemic toxicity can ultimately cause severe damage to the liver or kidneys.

Important notes

Milkweed (Asclepias spp.) is a highly toxic plant for cats. All parts of the plant, including dried leaves and stems, contain powerful toxins called cardiac glycosides. The highest concentration is found in the plant's milky sap. These toxins directly attack the heart by disrupting the normal electrical signals that control heartbeats. This forces the heart muscle to beat harder but at an abnormal rhythm, which can be very dangerous. The sap can also irritate the digestive system. If a cat eats milkweed or licks the sap, they may vomit, have diarrhea, or act weak and uncoordinated. More severe signs include difficulty breathing, muscle tremors, and irregular heartbeats. Because heart-related poisoning can worsen very quickly, contact a veterinarian immediately if you suspect your cat has been exposed.

• 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