Lenten Rose Poisoning in Dogs

Plants of the Helleborus genus, like the lenten rose, belong in the Buttercup (Ranunculaceae) family.  Although rose is included in many of the names given to Hellebore plants they are not closely related to the rose family. The lenten rose, like other Hellebores, can be moderately toxic if eaten in significant quantities. Although rarely fatal, ingesting large enough amounts of this plant can prove somewhat toxic. The unpleasant taste of these plants tends to prevent most animals from eating large enough quantities of this plant to become dangerously poisonous.

Lenten rose (Helleborus orientalis) is a winter-blooming plant that can cause cardiac arrhythmias and neurotoxic effects. Canines showing symptoms from eating lenten rose should be evaluated by a veterinarian.

Along with the systemic symptoms of poisoning, the sap from the lenten rose has been known to cause minor skin irritation in both humans and other animals. The resulting irritation usually clears up in less than an hour. 

• Abdominal pain
• Depression
• Diarrhea
• Difficulty breathing
• Excessive drooling
• Excessive thirst
• Heart rhythm abnormalities
• Lethargy
• Low blood pressure
• Paralysis
• Pawing at mouth (due to burning or tingling sensations)
• Seizures
• Sudden death
• Vomiting 
• Weakness

Types

• Helleborus argutifolius - A widely grown species of hellebore with green flowers that bloom in late winter and early spring
• Helleborus foetidus - Although known as stinking hellebore, the name is undeserved as the yellow-green flowers that bloom in the spring are not particularly smelly 
• Helleborus niger - Also known as the Christmas rose and black hellebore, the winter-blooming flowers are typically white or pink and the leaves dark and leathery
• Helleborus orientalis - This is the Helleborus species known as lenten rose; it has purple, green and rose-colored flowers that bloom in late winter 
• The Helleborus genus of plants contains approximately twenty species in the buttercup family of Ranunculaceae

Lenten rose belongs in the Helleborus genus which is a subset of the buttercup family (Ranunculaceae), rather than a part of the rose family (Rosaceae). All plants in the buttercup family contain various cardiac glycosides as well as a glucoside by the name of ranunculin. Ranunculin breaks down into the toxin protoanemonin during the digestive process.

When consumption of the lenten rose is witnessed, then the primary diagnosis will be based on the proper identification of the plant combined with the symptoms. Reactions to these plants are relatively mild unless large amounts of the plant have been eaten. If the signs and symptoms are incongruent with Helleborus toxicity or if the toxin is unknown, then diagnosis may be more involved. Your veterinarian will ask you about any opportunities for inappropriate eating that may have occurred as well a history of your pet’s health as information. Information about any supplements or medications your dog is taking will also be relevant to the treatment plan.  Drugs such as steroids, beta-blockers, and some chemotherapy agents may interact negatively with the cardiac glycosides present in lenten rose plants. 

General tests, such as a biochemistry profile, complete blood count, and urinalysis will be ordered at this time, and a physical examination will be completed with an emphasis on heart function and rhythm. Additional tests to check the functionality of the kidneys and the liver are also helpful in determining if any damage has occurred to these organs.

A thorough rinsing of the mouth is recommended to relieve the signs of pain or swelling in the mouth. If the amount that was consumed wasn’t overly large, and if it has been less than a few hours, you may be instructed on how to use hydrogen peroxide to properly induce vomiting in canines. If large volumes of the plant were consumed, or if acute symptoms are starting to develop, further treatment at your veterinarian's office will be required. Supportive measures such as IV fluids are necessary to fight dehydration as well as ensure that the proper sugar and electrolyte balances are maintained. 

Calcium should be avoided as an additive to IV fluids with lenten rose poisoning as the effects of the cardiac glycosides are enhanced by calcium. Activated charcoal is frequently utilized to soak up as many of the toxins as possible, generally, after  a gastric lavage is employed to void the various toxins from the patient’s system. If symptoms of cardiac involvement are present then antiarrhythmic drugs such as atropine sulfate, procainamide or lidocaine may be used to regulate the heart rate.

The prognosis of your dog will be dependent on how long it has been since the plant was ingested, how much was consumed, and what symptoms are presenting. Severe toxicity is rare due to the unpleasant taste and the possible burning and itching in the mouth. Symptoms from sampling these plants usually dissipate within 24 hours. If the quantities ingested lead to a veterinary visit, the recuperating patient should have a quiet, calm setting to return home to in order to speed recovery. This is of particular concern if the heart was affected due to cardiac glycoside involvement as further stress on the heart should be avoided. Anesthesia given to facilitate gastric lavage may cause short-term difficulties with coordination, and in that case, your dog may be confused and disoriented when he first returns home.