Top 5 Most Poisonous Plants for Dogs

Published: 19th July 2010
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The ASPCA has listed five poison plants as the deadliest for dogs we discuss of of these in detail here:


The beautiful Lily comes in multitudes of varieties, all are deadly to your dog. All parts of the lily are highly toxic.

Not only is the flowers beauty heart-stopping, scientists have found 38 known cardiac glycosides in the plant.

The Lilly is particularly deadly for cats.

The lily is found in nearly all locales, and warrant particular attention when they are used as part of indoor flower arrangements.

Ironically, the lilies are often given as funeral flowers.

Besides the cardiac threats, the sap of the lily also contains oxalate crystals which can cause mild irritation in humans but can cause fatal swelling by asphyxiation in dogs, in even small amounts.

Therefore, do not even let your dog swim in ponds or lakes with water lilies! Minuscule amounts of even diluted oxalate can cause serious problems for dogs!


We will be repeating ourselves throughout this article with the standard "seek immediate, emergency veterinary care" if you suspect your dog (or cat) ingested any part of a lily.

Treatment consists primarily of emptying the stomach, so do not discourage vomiting.

It is critical to begin vomit inducement treatments and gastric lavage within four hours of ingestion.

Hydrogen peroxide can be used to induce vomiting in a dog. But talk to your vet before doing so.

Treatment also include diuretics, to help prevent kidney failure.

Without treatment, poisoning by the Lily is nearly always fatal, and death usually occurs within four days due to either kidney or liver failure.

Azaleas (Rhododendron)

Azaleas are the most common poisonous flowers ingested by dogs. All parts of most azaleas contain grayanotoxin, which is sometimes known for the scientific name of the plant, rhodotoxin.

The toxins have mild effects on humans, but can be deadly for dogss, even in small amounts.

Common acute symptoms (other than witnessing ingestion) are nausea, salivation, vomiting, weakness, dizziness, difficulty in breathing and loss of balance.

Grayanotoxin is a neurotoxin and is also found in azalea pollen and nectar.

The toxin is potent enough to have caused illness in people who have eaten honey manufactured by bees that collected their pollen from rhododendron and azalea flowers. This condition is known as "Honey Intoxication".

More serious symptoms of poisoning, in dogs, present themselves 6 hours after ingestion and include depression, acute digestive upset, hyper salivation, nasal discharge, epiphora, projectile vomiting, frequent defecation, and difficulty swallowing.

Dogs usually slip into coma, before dying.

Some dogs slowly recover from poisoning from Azaleas after 48 hours.


Veterinarians, when able to treat the dog within 4 hours of the suspected poisoning, often attempt gastric lavage. The success of this procedure is highly dependent upon how long the leaves or other plant parts were in the Boxers digestive tract.

Additionally, veterinarians will usually follow a lavage with a charcoal treatment.

We cannot find sources stating owners should try to induce vomiting on their own. In any event, veterinarians should always be contacted before an owner attempts inducement.

Some doctors recommend beginning a course of antibiotics as a preventative against secondary pneumonias that often result from dogs inhaling their vomitus while suffering from grayanotoxin poisoning.

Sago Palm (Cycas revoluta)

This is the "oldest living known, plant".

The Sago Palm is a typical background plant for gardens in warm or tropical climes.

It is relatively low maintenance and has an outstanding ,rich, green cover, making it an attractive landscaping tool. Unfortunately, it is also highly toxic for both dogs and people.

Incidences of Sago poisoning in dogs have increased by 200% in the past five years as major retailers such as Walmart, Lowes and Home Depot are actively marketing the palms as house plants, often without poison warnings attached.

Ingestion results in death for 75% of dogs.

The home improvement store versions of these plants are potted for indoor growth as house plants making them obviously, more available to chewing canines.

Dogs, for some reason also find the palms quite tasty, and the most poisonous part of the plant: the seed or nut makes an attractive chew-toy as well.

All parts of the plant contain the neurotoxin Cycasin.

Symptoms, other than observing ingestion include: vomiting, loose or watery stools, drooling, foaming at the mouth (frothy, yellow), shaking or muscular dysfunctions and coma.

Dogs that do recover from this poison usually suffer moderate to severe liver damage, in some cases even cirrhosis.


We have read that inducing vomiting is proscribed for cases of cycasin ingestion.

A veterinarian should be called immediately upon suspicion of ingestion


Hydrogen Peroxide can be used to induce vomiting, but again, talk to your doctor first.

Treatment by doctors usually consists of lavage and activated charcoal as well as medications to evacuate the bowels.

Cycasin becomes active when it is broken down in the intestines, so attempting to circumvent the "intestine link" in the digestive process can sometimes have positive results.

However, the prognosis for animals that have ingested Sago Palm parts is bleak.

The only real treatment, in this case, is prevention.

Castor Bean

The castor plant is often recommended by landscapers as a natural mole repellent.

Unfortunately, all parts of the plants contain some toxins, enough toxin, if ingested, to cause adverse reactions in dogs.

Castor plant beans are fatal.

In fact, the toxin found in the castor bean: ricin, is often referred to as deadliest, naturally occurring poison.

The major players in WW I extracted ricin from castor beans for use in chemical warfare, but both sides found the toxin too dangerous and uncontrollable for effective deployment.

One milligram of Ricin is enough to kill the average sized adult man.

No wonder moles find the castor plants so repellant!

Besides playing a role in terrorist activities and covert assassinations, ricin and castor beans also form a main ingredient of Castrol motor oil.

Symptoms of ricin poisoning usually manifest themselves slowly over a 12 hour period. Causes of death are often paralysis of the respiratory system or heart failure.

Paralysis is often preceded by bouts of convulsions.

Other nerve agent symptoms such as extreme salivation/ drooling or foaming at the mouth can also present. Blood in watery stool and vomiting are often the first symptoms, occurring after one or two hours.


There is no antidote to ricin, so treatment is usually of symptoms and supportive and include attempts to clear the digestive tract of unmetabolised toxin or beans.

Simply keeping your dog away from these deadly plants is the only real alternative, here.


Along the lines of "I bet you didn't know": 'Oleander' is a general term used to describe two species within the genus Narium, which in turn, belongs to the Apocynaceae Family.

"Apocynum" is Latin for "away dog!".

So it should come as no surprise that Oleander is hazardous to a dog's health. Another member of the family is even known as "Dogbane", but its sticky sap merely deters dogs by irritating them.

Oleander goes a step further, and is actually quite deadly for your dogr (and you too for that matter).

The movie "White Oleander" isn't just Hollywood! These plants are highly toxic.

It is difficult to pin an exact set of symptoms on poisoning by oleander ingestion. This is because there are numerous different toxins to be found within the oleander itself.

The toxin named for the plant, "oleandrin" as well as another toxin, neriine, are both cardial glycosides. They are found throughout the plant and are particularly prevalent in the sap.

So cardiac symptoms are often associated with Oleander poisoning, such as a racing heart beat followed by periods of extremely slow rates- or heartbeats with no discernible rhythm.

However, also in the oleander, particularly in the bark, there is a nerve agent called Rosagenia. Therefore, nerve agent symptoms, i.e. salivation, drooling, twitching , disorientation and general malaise can also manifest themselves.

The gastro-intestinal system also responds to oleander through vomiting and diarrhea. In some cases, the nerve agents may cause internal bleeding and therefore, blood in the stool.


Vomiting should be encouraged, if not induced (under a veterinarian's direction); in the event your Boxer ingests Oleander.

A 'fortunate' characteristic of Oleander poisoning is that symptoms often appear rapidly enough to offer some window for treatment.

A less fortunate effect is that on the heart, particularly for dogs. Many of the life saving cardio-vascular treatments available to humans are not yet applicable to canines. So the mortality rate is correspondingly higher.

Veterinarians will often perform a gastric lavage and administer charcoal to absorb any toxins left in the digestive tract.

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