Pacific Yew Poisoning in Dogs

The Pacific yew is considered a small tree or very large shrub, but it can grow as tall as 50 feet. The foliage is evergreen needles about one inch long with small, yellow flowers growing underneath. The flowers turn into juicy, round fruit (berries) which are dark orange or red with one seed in the middle. The foliage is more toxic than the seeds, and the bark contains taxol, which is an alkaloid used in treating some cancers. The toxicity gets stronger when the seeds or foliage are dried and these seeds are spread by birds that swallow the seeds whole.

Pacific yew poisoning is an extremely serious condition caused by the ingestion of any part of a Pacific yew, including breathing in the pollen. If your dog eats the foliage or seeds of one of these trees, it can be fatal within just a few hours if it is not noticed and treated. This may sometimes happen when dogs are left outdoors for long periods of time. The toxins in the Pacific yew include taxine, which is a cardiotoxin (damages the heart muscle) that is absorbed so quickly into the bloodstream that sometimes there may not be any symptoms at all before sudden death. The heart just becomes weaker and stops being able to circulate the blood, eventually ending in heart failure.

Symptoms of Pacific yew poisoning vary greatly and depend on the route of transmission, and the health of your dog. Breathing in or coming into contact with the Pacific yew pollen can cause:

• Painful joints
• Extreme sleepiness
• Scratching
• Skin redness, rash, and inflammation
• Breathing difficulty

Ingesting any part of a Pacific yew may cause:

• Drooling
• Rapid heart rate
• Vomiting
• Weakness
• Dilated pupils
• Irregular heartbeat
• Dizziness (stumbling, falling down)
• Difficulty breathing
• Blue tint to lips and gums
• Muscle tremors
• Convulsions
• Seizures
• Coma
• Respiratory failure
• Cardiac arrest
• Sudden death

Types

The scientific name of the Pacific yew is Taxus brevifolia from the Taxaceae family. These trees are commonly found in British Columbia and Alberta in Canada, and several states in the United States (Washington, Oregon, Nevada, Alaska, Idaho, California, and Montana). Some of the other names the Pacific yew is known by are:

• Western yew
• Japanese yew
• English yew
• Anglo-Japanese yew
• Taxus occidentalis
• Taxus boursieri
• Taxus baccata

There are numerous toxic properties in the Pacific yew, which include:

• Both alkaloid and non-alkaloid diterpenoids (taxines A & B, paclitaxel, baccatin III, and 10-deacetylbaccatin III)
• Phenolic compounds (3,5 dimethoxyphenol)
• Flavonoids and bioflavonoids (myricetin and bilobetin)

It is essential that you get your dog to a veterinary professional right away if you suspect Pacific yew poisoning, even if there are no visible symptoms. If you bring a sample of the tree or a photograph, this can help speed up the diagnosis and treatment. Bringing your pet’s medical records may also help and be sure to mention if your dog is on any kind of medication. A physical examination will be done first, checking your dog’s blood pressure, oxygen levels, breath sounds, heart rate, respirations, weight, height, and body temperature. The veterinarian will hook your dog up to an EKG machine for an electrocardiogram, which measures heart functions. This is a very important diagnostic test because it will show multiple abnormal QRS waves, ventricular tachycardia, and longer QRS complexes. Also, an endoscopy should be done to check the airway for obstructions and remove any yew needles or seeds. This is done with a long, flexible tube called an endoscope.

Some laboratory tests will be done next, which may include a CBC (complete blood count), liquid or gas chromatography, biochemical profile, mass spectroscopy, urinalysis, and liver enzyme panel. In addition, some x-rays (radiographs) and an ultrasound can be used to check the heart muscle functioning and abdominal obstructions or lesions.

Treatment for Pacific yew poisoning will likely begin before or during the examination due to the high toxicity and rate of absorption. The veterinarian will first perform gastric lavage or emesis, decontamination with intravenous fluids, medications, and several days of hospitalization.

Gastric Lavage

Because of the emergence of the situation, the veterinarian may skip the emesis (vomiting) and do a gastric lavage to clear the toxins and plant particles still in the digestive system. This may be followed by activated charcoal to absorb any poisons that the lavage may have missed. 

Decontamination

Intravenous (IV) fluids will be given to flush the kidneys and to prevent dehydration. This will continue until your dog is ready to leave the clinic.

Medications

Atropine should be administered for heart rhythm irregularity, lidocaine can help with ventricular fibrillation, sodium bicarbonate for dysrhythmia, and phenobarbital for controlling seizures.

Hospitalization

Your veterinarian will need to keep your dog for several days to monitor heart rate, liver and kidney functions, and to provide fluids and oxygen therapy.

Many cases of Pacific yew poisoning are fatal if not treated within the first few hours. Your pet’s prognosis depends on the amount of toxins in the body and when you were able to obtain treatment. The veterinarian will let you know when you take your dog home what the prognosis is because each case is different. Preventing the ingestion of any more Pacific yew needles, seeds, or bark is essential for your pet’s recovery so you should make sure there is no point of contact. Observe your dog when outdoors as much as possible and continue to watch for complications. Call the veterinarian if you notice unusual behavior or distress, or have any questions.