Oxalate containing plants

A number of plants including Dieffenbachia spp , Zantedeschia spp , Epipremnun aureum , Philodendron spp, and Spathiphyllum spp.  contain insoluble calcium oxalate crystals.

Rhubarb ( Rheum rhabarbarum),  contains anthraquinones and soluble oxalates in small quantities (about 0.28% dry weight of leaf material) . Oxalis spp. (sorrel, wood sorrel, shamrock, soursob, Bermuda buttercup, and Irish shamrock) can contain up to 16% of dry matter as soluble oxalates.

Source : Plants of the Araceae family

 Toxic Principle

• All parts are usually poisonous. However, the leaves may sometimes do not have the toxin.
• Calcium oxalate crystals are felt to be one cause of the clinical signs. Recently toxicity has also been attributed to several proteolytic enzymes, which trigger the release of some potent kinins and histamines by the body.
• These kinins in turn cause several local reactions, which may be aggravated by the sharp calcium oxalate crystals contained in the plant tissues.
• Calcium oxalate crystals are thought to mechanically damage cells in the mouth during ingestion and may allow toxin to enter and create cellular havoc.

Clinical Signs:

• Immediate evidence of pain and irritation upon chewing.
• Shaking of head
• Intense salivation and change in phonation.
• Swelling of the mucous membranes of the pharynx and tongue.
• Severe dyspnoea may develop, but obstruction rarely develops.
• Nausea, vomiting, diarrhoea, secondary dehydration, electrolyte imbalance and shock are possible.
• Very rarely – irregular heart beat, mydriasis, coma and death.

 Treatment:

• Rinse mouth.
• Activated charcoal will help in adsorbing the toxins.
• Oral calcium (e.g., milk) may be helpful in precipitating any soluble oxalates.
• Antihistaminics.
• Symptomatic and supportive care with IV fluids if vomiting or diarrhea are persistent causing dehydration or shock.