According to the ASPCA, Spathyphyllum is only poisonous to cats and dogs if the leaves are eaten in large amounts. The toxic substance in this plant is the insoluble calcium oxylate crystals contained in the juice or sap, which lodge in the tissues and cause irritation and swelling. If the swelling is severe, it can block the airways.
Symptoms of calcium oxylate crystal ingestion include:
- Oral irritation
- Excessive drooling
- Difficulty swallowing
- Intense burning and irritation of mouth, tongue, and lips
If your cat has ingested a small quantity of Spathiphyllum leaves, give her milk, which dissolves the crystals, and then watch her carefully. She will be uncomfortable for a time but will likely survive. If your cat has ingested a large amount of leaves or is having difficulty breathing, seek veterinary help immediately.