by Dr. Stacy Armstrong, DVM, DACVECC
What is it? Which parts are toxic?
Ornamental evergreen shrub with leathery, dark green leaves. The flowers are borne in terminal clusters of dark red, pink, white. All parts of the plant are toxic.
Toxins? Clinical signs?
Dried and fresh leaves are highly toxic because they contain cardiac glycosides. The plant can cause sudden death with vomiting, diarrhea and heart failure. Experimentally, oleander is rapidly absorbed. There are reports of dogs dying after only ingesting a few leaves. More commonly, the toxic signs appear 8-24 hours after exposure.
Signs of poisoning often begin as vomiting or diarrhea. Variable irregular heartbeats, anxiety, dilated pupils (less common), muscle twitching, sweating, obtunded behavior and weakness can also be seen. Clinical signs often worsen over 24 to 48 hours as cardiac glycosides are excreted in bile and reabsorbed via the enterohepatic route. This tends to concentrate circulating toxin and worsen the clinical picture over this time frame.
Some sources report the toxic dose to be ~ 30mg/kg but there are reports of dogs dying from ingesting a small as 1 leaf. Fresh material contains saponins that are irritating to mucosa and are rarely ingested voluntarily. Dried leaves are seemingly more palatable and toxicity is not diminished by drying.
Therapy
If early in exposure, vomiting can be initiated (if appropriate).
Therapy is largely supportive however, repeat dosages of activated charcoal is likely useful because it may block the enterohepatic reabsorption. Specific antidote (DigibindTM) cross reacts with oleander glycosides and allows for excretion of the toxin in urine. Digibind is expensive and is only recommended when the irregular heartbeats (arrhythmias) are not responding to traditional anti-arrhythmic drugs. ECG monitoring and addressing specific arrhythmias as they arise is prudent due to the progressive and variable nature of arrhythmias with this intoxication.
Close monitoring of electrolytes, especially potassium is also important.
Prognosis
Many times, animals poisoned with oleander are found dead. In animals that are found and treated, they may still die within hours to several days. If the animals survive the initial insult, there should not be any long term effects.
If you suspect your pet has ingested this plant, contact Critical Care & Veterinary Specialists of Sarasota, or your local veterinarian right away!
