Nephthytis Poisoning in Dogs

Nephthytis plants (Syngonium podophyllum), also commonly known as arrowhead plants, goosefoot, and American evergreen, have conspicuous cream and white marking on their spade-shaped leaves. They have been naturalized in areas of Florida, Texas, and Hawaii but are more often found as a houseplant, often in hanging baskets. All portions of the nephthytis plant can contain the insoluble calcium oxalate crystals that cause intense oral pain irritation when chewed, and gastrointestinal distress if swallowed. The intense irritation and swelling caused by munching on these plants usually inhibit dogs from doing more than sampling the plant. On rare occasions, dogs may consume larger amounts of the plant material. On those occasions, your canine companion may require a visit to the veterinarian’s office for additional treatment.

The nephthytis plant (Syngonium podophyllum) is one of several that contain insoluble calcium oxalate crystals. These crystals can cause severe irritation to both the oral cavity and gastrointestinal system.

Insoluble calcium oxalate crystals are contained in all of the cells of the nephthytis plant. When chewed or swallowed these crystals can cause your pet distress in the form of: 

• Cardiac arrhythmia
• Diarrhea
• Dilated eyes 
• Difficulty swallowing
• Excessive drooling
• Hoarse barking
• Labored breathing
• Loss of appetite
• Numbness of exposed area
• Obstruction of the airway
• Pawing/rubbing at the face or mouth
• Swelling of the lips or tongue
• Vocalization
• Vomiting  

Types 

The nephthytis plant is also commonly known as  the African evergreen, American evergreen, arrowhead vine, goosefoot plant, and trileaf wonder. There are many varieties of plants that contain insoluble calcium oxalate crystals which are responsible for the irritation and swelling from contact with the nephthytis plants. These plants can include: 

• Calla or arum lily 
• Chinese evergreen
• Devil’s ivy 
• Dumbcane 
• Elephant’s Ear 
• Fruit salad plant 
• Jack-in-the-pulpit
• Peace lily 
• Philodendron 
• Rhubarb
• Skunk cabbage 
• Wild calla

The nephthytis plant contains the insoluble calcium oxalate crystals that cause the pain and inflammation in all of its parts. Insoluble calcium oxalates are calcium salts of oxalic acid which produce either numbness or irritation to the tissues it contacts. Chewing any portion of the plant usually causes immediate pain and inflammation to the oral tissues and throat area as the crystals insert themselves into the skin and mucous membranes. When the sap or plant material is actually swallowed, that irritation extends to the throat and down into the GI tract, which causes internal swelling and severe pain. Swelling in the throat can occasionally block the airway, making this condition potentially life-threatening.

The oral pain and swelling due to the exposure to the nephthytis plant and its calcium oxalate crystals will appear right away. Unlike the oral symptoms, gastrointestinal signs may take as long as two hours to appear. If you are uncertain what toxin your pet has ingested or if your dog swallowed sizeable amounts of the foliage your veterinarian may recommend a visit to the office. Your dog’s doctor will pay particular attention to any information about possible exposure to household or gardening products, foraging opportunities, and prescriptions or supplements that your dog may also be taking. 

General blood work such as a complete blood count and biochemistry profile may be ordered at this time as well as a urinalysis. These tests are done in an attempt to uncover any concurrent disorders or diseases as well as to determine the overall condition of the animal. If your dog has ingested enough of the plant material that vomiting is occurring, then the vomitus will also be examined and tested for toxins. Plant material found in the vomit may help confirm the diagnosis.

You can start treatment at home by using clean water to rinse the mouth and other areas that were affected thoroughly. This removes as many of the crystals from the skin and soft tissues as possible to reduce further swelling. You may want to also offer your dog something cool to eat or drink to ease the oral pain until you are able to contact your veterinarian. In most cases, the discomfort and unpleasant taste will prevent most canines from consuming substantial amounts of the actual plant, so rinsing the mouth area may be adequate treatment, however, your veterinarian may recommend an appropriate pain reliever or antihistamine if mild symptoms develop.

In cases that involve the ingestion of larger amounts of plant material or sap, you may need to transport your pet to the veterinary clinic for supportive treatment. IV fluids with electrolytes will be most likely administered at the veterinarian’s office to prevent dehydration and if an antihistamine was not previously recommended it may be dispensed at this time as an intramuscular injection. Gastroprotective medications are occasionally recommended to avoid physical damage from the crystals to the lining of the stomach. If the airway is swollen enough to cause any sort of blockage, your canine may need to be kept under observation at the clinic until the swelling subsides.

Dogs who have eaten smaller amounts of the plants such as the nephthytis plant, which contain insoluble calcium oxalate crystals usually have a positive prognosis. The effects from the crystals in the mouth and gastrointestinal tract are generally eliminated within twelve to twenty-four hours from ingestion. Swelling that occurs in the airway should be evaluated by a veterinarian and may worsen the prognosis. Massive doses of the plant are rare due to the initial pain and discomfort in the mouth. When larger doses do occur they can cause long-term kidney and liver damage so the kidneys and liver may require regular monitoring after the ingestion of substantial quantities of plant material.