Shamrock Poisoning in Dogs

The genus of plant known as Oxalis includes several varieties of shamrock plants and wood sorrels. All parts of the shamrock plant contain soluble calcium oxalate crystals. Oxalate crystals can cause diarrhea and excessive salivation when chewed or swallowed. Consistent consumption of the plant can lead to metabolic disturbances and kidney damage. On rare occasions, your dog may eat large amounts of plant material over a long period of time, causing stress on kidney function as well as changes in electrolyte and hormone levels. On those occasions, your canine companion will require an emergency visit to the veterinarian’s office.

Several varieties of the Oxalis genus are commonly known as shamrock. They contain soluble calcium oxalate crystals which cause possible renal failure if absorbed into the bloodstream.

The shamrock plant contains soluble calcium oxalate crystals in all parts of the plant. When chewed or swallowed these crystals can cause: 

• Blood in urine
• Tremors 
• Diarrhea
• Excessive drooling
• Lethargy
• Kidney failure
• Labored breathing
• Loss of appetite
• Frequent urination
• Excessive thirst
• Pawing/rubbing at the face or mouth
• Vocalization
• Vomiting

Types

The Oxalis genus is a large genus in the wood-sorrel family of Oxalidaceae.  It is most commonly known as the shamrock but also goes by the name of sourgrass and wood-sorrel. This should not be confused with Trifolium variety of clover, which is also sometimes referred to as a shamrock but does not contain oxalate crystals. 

Other types of plants that contain soluble calcium oxalate crystals can include: 

• Starfruit (Averrhoa carambola)
• Shamrock (Oxalis spp)
• Wood Sorrel (Oxalis acetosella)

When ingested in significant amounts, the oxalates in the plant can combine in the stomach and intestines. Additionally, once the calcium oxalate dissolves into the bloodstream, it binds with calcium, effectively removing it from the system. The sudden drop in usable calcium can have a destructive effect on the kidneys.

On any occasion, a pet who is displaying symptoms of feeling unwell should be taken to the veterinarian for an evaluation. Bring a portion of the plant along with you for the veterinary team to identify. If your dog has vomited while at home, bring a sample to the clinic; plant material in the vomitus can assist with the diagnosis.

If the source of the toxicity is unknown, your veterinarian will take special note of any opportunities for inappropriate eating (such as foraging in trash or investigation of non-food items around the home) as well as any prescriptions or supplements that are being administered to your dog. A biochemistry profile, complete blood count (CBC), and urinalysis are likely to be ordered at this time. This is done to uncover any concurrent diseases or disorders, to confirm the type of toxin, and to assess renal function. In the case of shamrock poisoning, blood markers will highlight hormonal and metabolic abnormalities as well as a decrease in calcium levels.

When the oxalates from the shamrock plant enter the bloodtream, systemic changes, due to the binding of the salts with the calcium and magnesium in the blood, occur. Because the calcium oxalate passes through the kidneys, renal function will be put under stress and renal failure could occur. 

Intravenous fluid treatment will be given to prevent dehydration and help support the kidneys. As well, electrolytes will be administered along with cathartic medication to encourage movement of the bowels. The combination of bowel and urinary activity will increase the rate of elimination of the toxins. Activated charcoal may be used to help bind the toxins within the stomach in order to discourage further absorption. 

The prognosis for dogs affected by sampling just small amounts of the plants containing the soluble calcium oxalate crystals is usually quite good, although a dog with concurrent kidney problems may experience more serious effects from the toxicity. Large quantities of this toxin usually leave the kidneys with permanent damage. Your veterinarian will most likely recommend increasing the frequency of monitoring in regards to the viability of your pet’s kidneys moving forward.

Fortunately, fatalities from the ingestion of this plant are rare. It is best to discourage your pet from grazing or sampling any plant material; not only is the digestive system of the canine not made for processing large amounts of greenery, plants can often cause toxicity ranging from mild to severe.