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1051.e2 Yew Toxicosis

Yew Toxicosis Client Education
Sheet
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• Hypotension
BASIC INFORMATION
• Respiratory distress or arrest of vomiting, followed by administration of acti-
vated charcoal can be lifesaving, particularly if
Definition implemented within 2 hours of ingestion, before
Yew toxicosis results from accidental ingestion, Etiology and Pathophysiology the onset of clinical signs of toxicosis. If clinical
typically by dogs, of dried or fresh yew (Taxus • Taxus spp (yew) are commonly used as signs are present, treatment consists of managing
spp) plant material; it is followed by develop- ornamental evergreen shrubs: Japanese yew cardiac arrhythmias, controlling seizures, and
ment of vomiting, muscle weakness, seizures, (T. cuspidata), English yew (T. baccata), providing supportive care as needed.
cardiac arrhythmias, coma, and death. Taxine American yew (T, canadensis), Chinese yew
A and B are the toxic alkaloids. (Taxus chinensis), Pacific or western yew (T. Acute General Treatment
brevifolia), Florida yew (T. floridana) • Evacuation of ingested plant material: in
Epidemiology • Yew alkaloids (taxines) block calcium and animals not showing clinical signs
SPECIES, AGE, SEX sodium ion channels, leading to bradycardia, ○ Dogs: apomorphine 0.03-0.04 mg/kg
Dogs are more likely to be involved than cats; all heart block, and ultimately cardiac arrest. IV or IM or crush tablet portion with
breeds and ages and both sexes are susceptible. water and instill into conjunctival sac and
DIAGNOSIS rinse after emesis; hydrogen peroxide 3%,
RISK FACTORS 2.2 mL/kg PO (max, 45 mL [in large
• Yews are toxic as green and dried plant Diagnostic Overview dogs]) and repeat in 10-15 minutes if
material. Diagnosis generally is based on known or no vomiting. Emesis may not remove all
• All parts of the yew are toxic except for the possible ingestion of yew, and confirmation plant material from the GI tract.
red, fleshy fruit (the aril) surrounding the is by identification of plant parts in vomitus. ○ Cats: dexmedetomidine 7 mcg/kg IV or
hard seed. The hard seed coat is resistant to Extremely rapid course of toxicosis means IM; xylazine 0.44 mg/kg IM
digestive enzymes. Clinical signs are unlikely that diagnosis is often retrospective (made at ○ Gastric lavage (plant material not easily
if the seed is swallowed whole, but absorp- postmortem exam). removed through tube)
tion from a cracked or partly chewed seed ○ Endoscopic removal of plant parts
is possible. Differential Diagnosis ○ Activated charcoal 1-2 g/kg PO with a
• Taxus brevifolia contains only minimal con- • Cardiac glycoside–containing plants (e.g., cathartic such as sorbitol (70%) 1-3 mL/
centrations of toxic alkaloids and therefore oleander, foxglove) kg; mix with charcoal; use labeled dose
has lower toxic potential than other yews. • Calcium channel blockers (diltiazem, for commercial products.
verapamil) toxicosis • Treat cardiac arrhythmias as needed.
GEOGRAPHY AND SEASONALITY • Caffeine toxicosis (methylxanthines) ○ Ventricular tachyarrhythmias: correct
• The most common ornamental yews are hypokalemia (rare) if present and consider
Taxus baccata (English yew) and Taxus Initial Database lidocaine (dogs) 2 mg/kg IV; in cats,
cuspidata (Japanese yew), but it may vary • CBC, serum biochemistry profile, urinalysis: use with caution; procainamide (dogs)
geographically. In the eastern United States, hypokalemia possible 2-4 mg/kg IV and (cats) 1-2 mg/kg IV;
Taxus canadensis (American yew) is the • Electrocardiogram (ECG): wide variety of propranolol 0.02-0.1 mg/kg slow IV or
most common; in Florida, Taxus floridana arrhythmias is possible, most commonly esmolol 0.05-0.1 mg/kg/min IV CRI
is the most common native species; and atrioventricular (AV) block, ventricular tachy- titrated to effect or by intermittent IV
in the western United States, T. brevifolia cardia, and ultimately with severe intoxications, bolus doses of 0.05-0.1 mg/kg q 5 minutes
(western or Pacific yew) is most frequently ventricular fibrillation/cardiac arrest up to a maximum of 0.5 mg/kg
seen. • Blood pressure: hypotension possible ○ Sinus bradycardia: atropine 0.04 mg/kg
• Taxine content is often higher in the winter IV
than in the summer. Advanced or Confirmatory Testing • Control seizures: diazepam (dogs/cats) 0.25-
• Taxines (or metabolites) can be identified in 1.0 mg/kg IV or phenobarbital (dogs/cats):
Clinical Presentation vomitus and stomach contents by gas chro- 2-3 mg/kg IV, with higher doses often used
HISTORY, CHIEF COMPLAINT matography, mass spectrometry, and silica in dogs
• History of exposure to dried or fresh plant gel thin-layer chromatography, although the • IV fluids and oxygen as needed
material lengthy turnaround time of such advanced • Correct electrolyte abnormalities as needed.
• Recent history of vomiting, with the presence testing usually precludes its use clinically.
of plant material noted in the vomitus • Necropsy: the diagnosis of yew poisoning is Drug Interactions
• The onset of systemic clinical signs is generally based on the presence of yew plant Sodium channel blockers and calcium channel
extremely rapid (within 30 minutes to 3 material in the gastrointestinal (GI) tract. blockers may potentiate arrhythmias.
hours after ingestion), and progression to Taxine affects electrical activity of the heart,
death may happen in a few hours. and no significant lesions are typically found Recommended Monitoring
• In increasing degree of severity over time, at necropsy. Fatty degeneration of the kidney, • ECG (arrhythmias)
the spectrum of clinical complaints includes congestion of lungs, and inflammation of • Blood pressure (hypotension)
vomiting, muscle weakness, seizures, coma, the GI tract are possible. • Serum electrolytes
and death. • Central nervous system (CNS) signs
TREATMENT • Respiratory rate and effort
PHYSICAL EXAM FINDINGS
• Signs of abdominal pain Treatment Overview PROGNOSIS & OUTCOME
• Mydriasis Given the rapid course of progression and
• Tachycardia or bradycardia (fairly common possibility of fatal intoxication, yew toxicosis • Good if treated early and intensively (before
with yew toxicosis) is considered a medical emergency. Induction onset of clinical signs)

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