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21 NOVEMBER/DECEMBER 2017 ■ TVPJOURNAL.COM PRACTICAL TOXICOLOGY signs have been reported in dogs and include nystagmus, tremors, seizures, and disorientation. Ingestion of kalanchoe warrants decontamination (asymptomatic pets only). Monitor pets for clinical signs at a veterinary hospital. In most cases, signs develop within a few hours, but onset can be delayed up to 12 hours. Any pet developing clinical signs after kalanchoe ingestion should have heart rhythm, blood pressure, and electrolytes monitored. Hyperglycemia has been reported in kalanchoe intoxications, although many cardiotoxic substances cause hypoglycemia instead. Gastrointestinal signs are managed as needed, and fluids should be administered. Add dextrose to the fluids if hyperkalemia is present. Manage vomiting and gastrointestinal clinical signs with antiemetics and histamine-2 blockers. Antiarrhythmic drugs ( Table 1 ) should be used as needed. Treat the specific arrhythmia. A digoxin-specific immune Fab (Digibind; DigiFab, digifab.us ) is indicated when serum K + >5 mEq/L or if arrhythmias do not respond to standard therapy. In most veterinary cases, the initial dose is 1 to 2 vials empirically. The vials should be reconstituted in sterile water and then added to 50 mL of saline. Administer IV over 30 minutes (improvement is noted within 20 minutes to a few hours). Monitor potassium and electrocardiograms while maintaining fluid therapy. Sometimes, the toxin redistributes in tissues and signs reappear. The prognosis is excellent if only mild gastrointestinal signs develop. If significant cardiovascular signs and/ or hyperkalemia develop, the prognosis is guarded. MISTLETOE (PHORADENDRON SPECIES) There has been significant confusion over the years between European and American mistletoe; the genus discussed here, Phoradendron, is the American mistletoe. The plants are semiparasitic and live on tree branches. One theory suggests toxicity may vary depending on the species of tree in which the mistletoe grows. Mistletoe contains a variety of potentially toxic compounds, although serious signs are uncommon. Human poison control centers have published retrospective studies of mistletoe ingestions. Most people remained asymptomatic, and gastrointestinal effects were the primary clinical signs in symptomatic cases. In rare cases, hypotension, collapse, ataxia, seizures, and death were reported. 4–6 Mistletoe contains glycoprotein lectins, which are same type of toxin found in castor beans (Ricinus communis). Mistletoe lectins (phoratoxin and ligatoxin A) are significantly less toxic than ricin. The toxins act as a cardiac depressant, causing hypotension, bradycardia, and decreased contractility. The most common clinical signs include vomiting, depression, and diarrhea. Rarely, with large ingestions, hypotension may be seen. Most ingestions are managed at home by withholding food and water. Large ingestions warrant decontamination. Pets experiencing more than mild gastrointestinal upset should be evaluated for hypotension. Prognosis is generally good. POINSETTIA (EUPHORBIA PULCHERRIMA) Poinsettia is an especially popular Christmas plant. The upper leaves come in a variety of colors and resemble a flower. The flowers are the tiny yellow structures resembling stamens. Poinsettias have received a great deal of negative publicity based on a probable urban legend from 1919. All Euphorbia plants produce a milky sap containing latex irritants. However, poinsettias are much less potent than many Euphorbia species. Diterpenoid euphorbol esters and steroids with saponin-like TABLE 1 Antiarrhythmic Therapies for Dogs and Cats ARRHYTHMIA DRUG DOSAGE Bradycardia Atropine 0.04 mg/kg IV Tachycardia Propranolol 0.02 mg/kg slow IV Tachycardia with hypertension Atenolol (β1-specific blocker) or 0.25–1 mg/kg PO q12h (dogs) 6.25 mg/cat q12h (cats) Esmolol (β1-specific blocker) 0.25–0.5 mg/kg IV loading dose, then 10–200 mcg/kg/min IV as a continuous rate infusion 3