• Electrocardiogram (ECG; see p. 1253): a wide variety of arrhythmias is possible and fairly common, most commonly atrioventricular (AV) block, ventricular tachycardia, and (ultimately with severe intoxications) ventricular fibrillation/cardiac arrest.

• Blood pressure (see p. 1209) (hypotension possible)

ADVANCED OR CONFIRMATORY TESTING

• Taxines (or metabolites) can be identified in vomitus and stomach contents by gas chromatography, mass spectrometry, and silica gel thin-layer chromatography, although the lengthy turnaround time of such advanced testing usually precludes its use clinically.

• Necropsy: the diagnosis of yew poisoning is generally based on the presence of yew plant in the gut. Taxine affects electrical activity of the heart, so no significant lesions are typically found on necropsy. Fatty degeneration of the kidney, congestion of lungs, and inflammation of the gastrointestinal (GI) tract are possible.

TREATMENT

TREATMENT OVERVIEW

Given the rapid course of progression and possibility of fatal intoxication, yew toxicosis is considered a medical emergency. Induction of vomiting, followed by administration of activated charcoal can be lifesaving, particularly if implemented within 2 hours of ingestion prior to the onset of clinical signs of toxicosis. If clinical signs are present, general treatment consists of managing cardiac arrhythmias, controlling seizures, and providing supportive care as needed.

ACUTE GENERAL TREATMENT

• Evacuation of ingested plant material: in animals not showing clinical signs:

○ Apomorphine, 0.03-0.04 mg/kg IV or IM, or crush tablet portion with water and instill into conjunctival sac and rinse following emesis; or hydrogen peroxide 3%, 2 mL/kg PO (max 45 mL [in large dogs]), repeat in 10 to 15 minutes if no vomiting. Emesis may not remove all plant material from the GI tract. If the ingestion was small and/or the patient has not eaten anything else, some clinicians feed a tasty meal immediately prior to inducing vomiting, to allow mixing and agglutination of plant material with food that is then vomited.

○ Gastric lavage (plant material not easily removed through tube)

○ Endoscopic removal of plant parts

○ Activated charcoal (1-2 g/kg PO) with a cathartic such as sorbitol (70%) 1-3 mL/kg; mix with charcoal; use labeled dose for commercial products.

• Treat cardiac arrhythmias as needed:

○ Ventricular tachyarrhythmias (see p. 1165): correct hypokalemia if present and consider lidocaine (dogs: 2 mg/kg IV; cats: use with caution), procainamide (dogs: 6-8 mg/kg IV; cats: 1-2 mg/kg IV), propranolol 0.1 mg/kg slow IV, or esmolol 0.2-0.5 mg/kg slow IV to effect.

○ Sinus bradycardia: atropine, 0.04 mg/kg IV

• Control seizures (see pp. 353 and 1009): diazepam (dogs/cats: 0.25-0.5 mg/kg IV) or phenobarbital (dogs/cats: 25 mg/kg IV, higher doses often used in dogs)

• IV fluids and oxygen as needed

• Correct electrolyte abnormalities as needed.