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18 PRACTICAL TOXICOLOGY PEER REVIEWED AMARYLLIS (AMARYLLIS OR HIPPEASTRUM SPECIES) Amaryllis is native to South America. It can be forced to bloom in winter, generally during the holiday season. The flowers come in a variety of colors, with red being popular for Christmas. Like other members of the Amaryllidaceae family, amaryllis contains the phenanthradine alkaloids lycorine and tazetine. These alkaloids reach concentrations of up to 0.5% in the bulb and leaves. Lycorine is the toxic principle responsible for most of the clinical effects. Lycorine acts on neurokinin-1 receptors, with some effect on the 5-hydroxytryptamine receptors. Many other alkaloids are present in the plant as well. A lycorine study in dogs demonstrated that 0.5 to 2 mg/kg SC causes nausea and vomiting. 2 At 2 mg/kg SC, 100% of dogs vomited. The gastrointestinal effects of lycorine in the study lasted 2.5 hours. However, the oral bioavailability of lycorine in dogs is only 40%. Clinical signs would likely last longer when plant material is ingested and remains in the gastrointestinal tract. For most pets, ingesting leaf material results only in mild gastrointestinal upset, with clinical signs that may include mild to moderate vomiting, diarrhea, anorexia, and hypersalivation. Ingestion of portions of the bulb may cause more intense clinical signs, such as restlessness, tremors, or dyspnea, while large or massive bulb ingestions could cause hypotension, seizures, and sedation. Most cases of vomiting are managed at home by withholding food and water for several hours; additional treatment is rarely required. Moderate to severe vomiting can be managed with antiemetics. Maropitant (Cerenia; zoetisus.com ) is a neurokinin-1 receptor antagonist and is the antiemetic of choice. In a study of lycorine-induced vomiting in beagles, maropitant completely blocked vomiting when given before lycorine was administered. 1,2 On the basis of ASPCA Animal Poison Control Center data, maropitant is an effective antiemetic for pets that begin vomiting after amaryllis ingestion. Other antiemetics (ondansetron, metoclopramide) are not as effective as maropitant in these cases. Other supportive care includes IV fluids and, in severe cases, correction of electrolyte imbalances. Large ingestions of leaves and bulbs may require decontamination with induction of emesis (if within an appropriate time frame). Massive ingestions may require blood pressure monitoring. Prognosis is generally good for amaryllis ingestions, and, in most cases, signs resolve within 24 hours. CHRISTMAS CACTUS (SCHLUMBERGERA TRUNCATA) Christmas cactus is a native Brazilian plant and a member of the cactus family (another common name is crab's claw cactus). The plant is light sensitive and can be forced to bloom seasonally. In dogs and cats, the most common clinical signs of toxicosis include vomiting, lethargy, anorexia, diarrhea, and hypersalivation. Bloody vomiting and diarrhea can also occur. Ataxia has been reported in cats. Clinical signs are generally mild and resolve within a few hours. Treatment is generally managed at home by withholding food and water and giving the gastrointestinal tract a chance to recover. If vomiting or diarrhea is moderate to severe, the animal may require antiemetics and correction of dehydration or electrolyte imbalances. A bland diet may be indicated for several days. CHRISTMAS TREES Christmas trees are the ultimate Christmas season plants. Common species include firs (Abies and Pseudotsuga species), pines (Pinus species), cypresses (Cupressus species), spruces (Picea species), and cedars (Juniperus and Cedrus species). Most Christmas trees are cut before being brought into the house, although some have a root ball so the tree can be planted outdoors after the holidays. Cut trees are usually placed in a stand with a reservoir for water. Frequently, preservatives containing dextrose and fertilizers are added to the water. Drinking the preservative–water mix typically causes only mild, self-limiting gastrointestinal upset. If the water is not routinely changed, bacterial or fungal overgrowth can occur. Pets may ingest needles, cones, branches, and bark. Most Christmas trees contain essential oils (concentration and specific oils vary by species). Ingestion of large quantities of needles, cones, and parts of the tree may result in a gastrointestinal foreign body.