Periodic electrocardiographic monitoring of the QRS complex interval and other cardiac arrhythmias for several days after
exposure is important, even in asymptomatic animals. Avoid additional cardiac stressors or triggers of cardiac arrhythmias
such as exercise, transportation, or excitement. Administering atropine sulfate has been suggested to counteract the cardiotoxic
effects of taxines in domestic animals; however, Taxus species-induced arrhythmias in people are difficult to control.2,4 Use caution if administering atropine since it can increase myocardial oxygen demand and potentiate myocardial hypoxia and
dysfunction. Atropine is considered to be more effective in yew toxicosis if it is administered early. Repeated high doses
of intravenous lidocaine have been used successfully to control yew-induced ventricular fibrillation in one person.5 Intravenous boluses of hypertonic sodium bicarbonate were ineffective in reversing the widening of the QRS complex interval
in swine with T. x media toxicosis.6
Other treatments are essentially symptomatic and supportive: fluid therapy to support blood pressure and maintain hydration
and renal function; positive pressure ventilation if respiratory distress is present; antiemetics (e.g. metoclopramide 0.2 to 0.5 mg/kg orally, intravenously, or subcutaneously every eight hours); and gastrointestinal protectants
(e.g. kaolin and pectin 1 to 2 ml/kg orally every six to 12 hours). Aggressive behavior and seizures should also be controlled
(e.g. diazepam at 0.5 to 1 mg/kg intravenously or 4 mg/kg rectally in increments of 5 to 20 mg to effect).
Prognosis and prevention
Since yew toxicosis is often a postmortem diagnosis, preventing exposure is paramount. Make sure pet owners know that yew
branches or leaves should not be used as play items for dogs or as perches for companion birds. And owners should dispose
of yew trimmings by removing, burning, or burying the trimmings where animals cannot access them.
"Toxicology Brief" was contributed by R.B. Cope, BSc, BVSc, PhD, Department of Biomedical Sciences, College of Veterinary
Medicine, Oregon State University, Corvallis, OR, 97331. The department editor is Petra A. Volmer, DVM, MS, DABVT, DABT, College
of Veterinary Medicine, University of Illinois, Urbana, IL 61802.
REFERENCES
1. Burrows GE, Tyrl RJ. Taxaceae. In: Toxic plants of North America. Ames: Iowa State University Press, 2001;1149-1157.
2. Wilson CR, Sauer J, Hooser SB. Taxines: a review of the mechanism and toxicity of yew (Taxus spp.) alkaloids. Toxicon 2001;39:175-185.
3. Evans K, Cook J. Japanese yew poisoning in a dog. J Am Anim Hosp Assoc 1991;27:300-302.
4. Willaert W, Claessens P, Vankelecom B, et al. Intoxication with Taxus baccata: cardiac arrhythmias following yew leaves ingestion. Pacing Clin Electrophysiol 2002;25:511-512.
5. von Dach B, Streuli RA. Lidocaine treatment of poisoning with yew needles (Taxus baccata L.) [German]. Schweiz Med Wochenschr 1988;118:1113-1116.
6. Ruha AM, Tanen DA, Graeme KA, et al. Hypertonic sodium bicarbonate for Taxus media-induced cardiac toxicity in swine. Acad Emerg Med 2002;9:179-185.
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