Yellow Oleander Poisoning in Cats

Yellow oleander is extremely toxic, containing chemicals such as cardiac glycosides, cardenolides, thevetins A and B, thevetoxin, ruvosode, nerifolin, and peruvoside. This combination creates a lethal effect in most animals that attempt eating yellow oleander. All parts of the plant are considered toxic. Even small portions of the plant may have a deadly effect on the victim. Yellow oleander remains toxic if it is dried. The potency of the seeds leads this plant to be commonly used as a method of self-harm in many countries. 

The yellow oleander is a plant that is as dangerous as it is beautiful. It is classified as Thevetia peruviana of the Apocynaceae family of plants. Native to Central America, yellow oleander can be used in landscaping or be found growing wild in many of the warmer southern states. It is a very decorative shrub which can range from six to 20 feet in height. Yellow oleander is an evergreen that grows narrow, glossy dark green leaves that are leathery in texture. The flowers bloom at the end of the branch and may be yellow, apricot, or white in color. 

Symptoms generally have a rapid onset, showing up within the first three hours after ingestion, if not immediately. If it is suspected that your cat has eaten yellow oleander, it should be treated as a medical emergency. All signs to watch for are listed as follows:

• Nausea
• Vomiting
• Diarrhea (may be bloody)
• Excessive drooling
• Food aversion
• Depression
• Hypothermia
• Slow heart rate
• Slow capillary response time
• Tremors
• Arrhythmias
• Dilated pupils
• AV block (a heart block)
• Paralysis
• Coma

Yellow oleander may be found in gardens or growing wild in many of the warmer states that do not have a true winter. Eating a few leaves, chewing on a twig of the plant, or even drinking water that yellow oleander leaves have been sitting in may cause death. All cats allowed outdoors in warm climates are at risk of coming into contact with this plant.

If your cat begins exhibiting any of the symptoms above, or if you witnessed it eating yellow oleander plant material, bring it into the nearest veterinary clinic or animal hospital immediately. Treatment will likely be started before diagnosis is attempted. The vet may ask about the plants that you keep in or around your home and if you allow your cat to go outdoors. Providing your cat's full medical history can aid the vet in determining the cause of symptoms and how best to treat them. 

The veterinarian will then perform a complete physical examination of the cat to compile all of the symptoms that have manifested in the cat. All of the cat's vital functions will be measured at this time. The cat's temperature will likely be low and its heart rate slower than normal. An electrocardiogram will be used to monitor the rhythm of the heart. Blood tests will be needed to measure levels within the blood. Abnormally high levels of potassium may point to yellow oleander poisoning. Sometimes a diagnosis can only be made via autopsy post mortem.

There is no official antidote for yellow oleander poisoning. Treatment will depend on the symptoms that have developed in the cat. All effort will be made to stabilize the animal's basic functions.

Remove Stomach Contents 

The vet will empty the stomach either by emesis with hydrogen peroxide or by using gastric lavage (stomach pumping) to remove any remaining plant material before it has been digested.

Activated Charcoal 

Administering activated charcoal can prevent absorption of any more of the plant toxins residing in the digestive tract. The decision to use single or multiple doses shall be made at the vet's discretion. 

Medication 

A variety of medications may be used to treat arrhythmias of the heart. These include potassium chloride, Procainamide, dipotassium EDTA, atropine, FDP or lidocaine (which is the preferred medication). Digoxin-specific antibody fragments have been identified as having the possibility to counteract toxins from yellow oleander, however, this treatment is hard to obtain.

Fluid Therapy 

If the cat has become dehydrated, saline and electrolytes will be supplemented intravenously to the cat.

The overall prognosis will depend on how much of the plant has been eaten. If the cat has ingested very small amounts of the plant, the prognosis is guarded but recovery is possible. The cat may be left with permanent heart damage after the event. If a larger amount of yellow oleander has been consumed, death is likely. Within 24 hours the cat will become paralyzed, fall into a coma and die. Administering treatment quickly may slightly improve the outlook, however, recovery is unlikely. 

The best way to protect your cat from exposure to yellow oleander is by keeping it indoors. Some may choose to remove the plant from their garden as a further precaution.