Pacific Yew Poisoning in Cats

This evergreen is extremely poisonous for your cat because it contains taxines. The tiny red berries, twigs, and branches of the plant are equally poisonous. Your cat’s life can be threatened if it eats any part of this plant; the taxines cause life-threatening changes in blood pressure and heart rate, seizures, tremors, coma and, soon, death.

If you aren’t sure about the identification of a new plant, look at its leaves. The leaves of the Pacific yew range from 1 to 2.5 centimeters long and narrow, at 0.25 cm wide. Normally, you’ll find this shrub in forests in the western United States.

Pacific yew is called by several other names, including English yew, Japanese yew, western yew and Anglo-Japanese yew. Its scientific name is Taxus brevifolia and it resides in the Taxaceae family.

Symptoms of Pacific yew poisoning may develop rapidly and include:

• Tremors
• Difficulty breathing
• Nausea
• Vomiting
• Diarrhea
• Acute heart failure
• Dilated pupils
• Collapse

Unfortunately, if the cause of a cat’s symptoms is not known to be ingestion of Pacific Yew, the first sign of poisoning may be collapse or death. The oil irritants in Pacific Yew can cause acute gastroenteritis (vomiting and diarrhea), but this may not develop since animals may experience heart failure before other symptoms develop.

The causes of Pacific yew poisoning for cats are two volatile oils found within the shrub: Taxine A and Taxine B. These are known as direct cardiac myocyte calcium and sodium channel antagonists. They are potent, disturbing both sodium and calcium channel currents within the heart, working like verapamil (a calcium channel blocker) works. 

Essentially, Taxine A and Taxine B work by widening your cat’s blood vessels and affecting the degree the heart’s muscle fibers shorten when an electrical current stimulates them.

These volatile oils also suppress vascular smooth muscle contractions and can cause your cat’s blood pressure to fall. Your cat’s heart comes to a standstill, leading to its death.

Making the situation even more difficult for you and your cat is that you may not know when your cat ate the yew. Detectable clinical signs of poisoning can develop within minutes or several days later. Also, only a tiny amount of this plant is sufficient to poison your cat and kill it.

If you are able to get your cat to the vet quickly, have a sample of Pacific yew with you so he can correctly identify what is making your cat sick. The vet will take a history of potential exposure (all substances that could have poisoned your cat) and carry out a physical. Because time is so important, he will look for yew leaves or other evidence in your cat’s gastric contents.

The vet may also run a liquid chromatography and mass spectroscopy on the samples provided to determine what has made your cat so sick.

With Pacific yew poisoning, minutes matter. The vet will begin treatment immediately once he knows what is going on. He will induce vomiting (preferably within 30 minutes to 1 hour of your cat getting poisoned). This happens only with animals who are still not showing symptoms, because inducing vomiting in a cat with high amounts of taxine alkaloids in its body could cause cardiac arrest and central nervous system complications.

If induced vomiting is impossible, gastric lavage is the next step. This should be followed by a course of activated charcoal to help absorb the remainder of the toxins in your cat’s stomach.

Once all of the poison has been removed from your cat’s body, the vet will monitor your cat’s heart rhythms for several days. Your cat will have to stay calm and quiet during this time. Because cardiac arrhythmias induced by plants in the Taxus genus are so difficult to predict and control, medication may be used to counter the effects of the poisons. 

Other treatments include supportive fluid therapy, which helps maintain your cat’s blood pressure as well as keeping it properly hydrated. If your cat is still in gastric distress, the vet can give gastrointestinal medications, such as pectin and kaolin to coat its stomach. 

The only way for your cat to survive Pacific yew poisoning is not to come in contact with it. The earliest sign of exposure and poisoning is often death, making poisoning consequences significant. 

If you know you have this shrub on your property, removing and disposing of it may be the only way to prevent your pets coming into contact with it. 

In order to avoid contact with Pacific Yew in neighbors’ yards, it may be necessary to restrict your cat’s wanderings and keep it indoors.