Is Shamrock Plant (Oxalis) Toxic to Cats?

Is oxalis toxic to cats?

Shamrock plant (Oxalis spp)  is toxic to cats. The toxic principle is oxalic acid which is rapidly absorbed in the gastrointestinal tract and binds to systemic calcium causing blood calcium levels to drop suddenly (acute hypocalcemia) and calcium oxalate (CaOx) deposition in the renal tubules, leading to acute renal (kidney) failure.

Plant defences

Thorns on a rose

Plants have evolved many defence mechanisms to protect themselves from herbivory, such as thorns, trichomes (leaf hairs), chemicals and razor-sharp crystals. Oxalic acid is a common compound in plants and occurs in two forms; soluble and insoluble.

  • Insoluble oxalic acid is the most common type which forms clumps of needle-sharp crystals called raphides in the tissues. When an insect or animal chews these types of plant, raphides are released which cause intense pain to the oropharynx. Due to pain and discomfort, domestic pets will usually stop chewing plants containing insoluble calcium oxalates. Common houseplants which contain insoluble oxalates include Dieffenbachia (dumbcane), Zantedeschia (calla lily), Syngonium podophyllum (arrowhead plant),  Spathillium (peace lily), Philodendron, Epipremnum aureum (pothos), Schefflera (umbrella tree), Colocasia (elephant’s ear) and Aglaonema (Chinese evergreen).
  • Soluble oxalic acid-containing plants are considered more harmful because of the potential to cause hypocalcemia and acute kidney damage. Plants include spinach (which also contains insoluble calcium oxalate crystals) and rhubarb.

The degree of toxicity depends on the duration of exposure and the amount of plant consumed. Livestock are at greatest risk as they are more likely to consume large quantities of the plant. The bitter taste of oxalic acid is generally enough to deter most cats and dogs from eating enough to cause sickness.

Related: Plants toxic to cats

What is oxalis?

  • Family: Oxalidaceae
  • Botanical name: Oxalis spp.
  • Common names: Shamrock plant, Wood sorrel, False shamrock,  Wood plant, Good luck plant, Sorrel, Love plant
  • Plant type: Perennial
  • Toxicity: Toxic to cats
  • Toxic parts: All parts
  • Severity: Moderate
  • Toxic properties: Oxalic acid (soluble calcium oxalate)

Oxalis is a large genus of flowering perennials comprising of 800 species found throughout the world. Many oxalis species are considered weeds, however, some species are grown as houseplants. One of the most outstanding of the oxalis species is Oxalis triangularis, commonly known as purple oxalis.

Clinical signs

There is no toxic dose, and symptoms will depend on the amount of oxalis ingested as well as the overall health of the cat. Cats who are dehydrated or have chronic kidney disease are at increased risk.

  • Weakness
  • Lethargy
  • Hypersalivation (drooling)
  • Gastrointestinal signs (loss of appetite, vomiting, diarrhea)
  • Tremors secondary to hypocalcemia
  • Kidney damage 24-36 hours after ingestion (altered urine output, blood in the urine, increased thirst)

What should you do if your cat has ingested oxalis?

In most cases, cats will ingest an insignificant amount of oxalis to cause clinical signs. If a large amount has been ingested, seek immediate veterinary care.

As always, if you are unsure of the toxicity of a plant, contact your local veterinarian or animal poisons control for further advice.

Feature image Kevin, Flickr