Yellow Oleander Poisoning in Dogs

Yellow oleander (Thevetia peruviana) is found in central and southern Mexico as well as Central America and is closely related to the well-known “common” or “pink oleander” that is frequently encountered in the United States. Both types of oleander are a part of the Dogbane family and can be seen as decorative shrubs and trees. 

Yellow oleander is seen either as a small bush that is less than six feet in height or as a tree around 20 feet tall. The bush or tree will have stems or branches that turn outward as they age. The leaves are dark green and glossy and are either paired or in groups of three. The length of the leaves can be two to eight inches and they are thick and leathery. Yellow (and on occasion apricot or white) flowers grow in small groups at the end of each branch. 

The entire yellow oleander plant is toxic, containing glycosides oleandrin and nerioside. These have both a cardiotoxic and neurotoxic effect upon consumption.

Found in southern Mexico and Central America, yellow oleander is toxic, leading to neurologic, cardiovascular and gastrointestinal problems in dogs that ingest the plant.

Ingesting oleander will impact the cardiovascular, gastrointestinal and neurologic systems of your dog and symptoms will occur between 30 minutes to a few hours after the plant was consumed. Symptoms of yellow oleander poisoning in your dog may include the following:

• Significant stomach upset to include vomiting and diarrhea, either with or without blood
• Depression
• Unwillingness to eat
• Excessive drooling
• Hypothermia
• Weak pulse
• A decrease in gastrointestinal motility
• Loss of coordination
• Dilated pupils
• Congested mucus membranes
• Drowsiness and weakness
• Progressive paralysis
• Cardiovascular dysrhythmias
• Cold extremities
• Tremors
• Death

Types

The Nerium oleander is the most recognized species and is found in North America. The next most common type of oleander is the yellow oleander, called Thevetia peruviana, which can be found in Mexico and Central America.

All of the yellow oleander plant is toxic, containing the glycosides oleandrin and nerioside. These have a cardiotoxic and neurotoxic impact on your dog’s body. The toxicity is significant; dogs have been shown to get very sick simply by using an oleander stick as a fetch toy, and chewing on a twig or stick can even be fatal. 

It is believed that oleander have 30 types of cardiac glycosides. When hyperkalemia (potassium level in blood is higher than normal) occurs, the pulse of your dog will be affected and that can lead to problems in the heart muscle, nerve cells and muscle cells.

Should you know that your dog ingested yellow oleander or be concerned that he has, you will want to take him to the veterinarian immediately, even if you believe he only ate a small amount. The level of toxicity will depend not only on how much your dog ate, but his size and physical condition at the time he ingested the plant. If possible, it will be helpful to bring a sample of the plant that your dog consumed. You veterinarian will likely ask you how much you saw your dog ingest, along with when you first noticed symptoms.

Your veterinarian will conduct a physical examination, feeling the abdomen of your dog, and checking his mucous membranes and pulse rate. An electrocardiogram may be conducted to see if there are abnormalities within your dog’s heart. Blood tests will be given and the presence of hyperkalemia in your dog will point to the possibility of poison by yellow oleander. Your dog’s glucose, BUN and creatinine will also be looked at. The specific digoxin immunoassay (Digoxin III-Abbott Laboratories) is a quick, sensitive test that can confirm that oleandrin is present in your dog’s blood.

The recovery of your dog will depend on how much of the plant he has consumed, along with the amount of time that has passed before he begins treatment. Should your dog have ingested a large amount and it not be discovered and treated quickly, his prognosis is poor. Should he have ingested a small or medium amount and is treated quickly, his prognosis will be much better. 

There is not a specific treatment to resolve the problems occurring as a result of the cardiac glycosides that are in the oleander plant. This being the case, even with prompt treatment, a dog can still die. Your veterinarian will focus on treating your dog’s symptoms and help him to feel better. Vomiting will be induced as soon as possible. An emetic may be used (for example 3% hydrogen peroxide at a dosage of 1 teaspoon for every 10 pounds of weight). Your veterinarian may choose to pump your dog’s stomach and/or use activated medical charcoal to help absorb the toxins in your dog’s body. 

In severe cases of poisoning, your veterinarian may choose to continuously monitor your dog’s heart in order to detect any arrhythmias. Should there be any cardiac issues, they may be treated with antiarrhythmic drugs like potassium chloride, procainamide, lidocaine, dipotassium EDTA or atropine sulfate.

If your dog is experiencing dehydration, your veterinarian may administer intravenous fluids (without potassium or calcium). Fructose-1,6-diphosphate (FDP) has been found to prevent the occurrence of hyperkalemia as well as reverse dysrhythmias. 

Should your dog have experienced poisoning from the yellow oleander he should be kept as calm as possible to ensure he does not experience additional stress on his heart.

Every case of yellow oleander poisoning is different. Prompt medical attention and treatment are imperative for a positive outcome. It will be important to follow the instructions of your veterinarian and attend follow up appointments as recommended. Your dog will likely require significant down-time to recover after poisoning from the yellow oleander plant.