7 Surprisingly Common Plants That Are Poisonous to Pets

Written and submitted by guest author, Emily Jackson

Most pet owners know that some plants, including lilies, poison ivy, azalea, daffodil, and oak, are harmful to their cats and dogs. However, you may be shocked to find out that we are surrounded by surprisingly common plants that are poisonous to pets.

Always practice care when planting particular veggies, herbs, and flowers in your garden or windowsills to protect your beloved furry friends. If you can't live without some of the listed plants, be sure to supervise your animals carefully, especially curious cats.

Common Plants Poisonous to Pets

1. Aloe Vera: A Common Household Plant Toxin

Among the most surprising is Aloe Vera, known as a plant highly beneficial for humans. While the plant’s internal gel is mostly harmless, its skin is toxic to both cats and dogs. Chemicals, saponins (glycosides), located in the skin of the leaf have antiseptic and cleansing properties in humans. Alternatively, these chemicals can cause vomiting, diarrhea, tremors, depression, lethargy, and extremely irritated skin in your pet.

Fortunately, symptoms are usually not severe, unless when your pet ingests a large piece of the plant. If you spot red urine along with other symptoms, take your pet to the vet right away.

2. Potatoes: An Unexpected Kitchen Danger

Recently, the FDA (the US Food and Drug Administration) announced that DCM (canine dilated cardiomyopathy) was reported in dogs eating pet food containing potatoes and peas as primary ingredients.

This disease usually occurs in genetically prone breeds. However, veterinarians have discovered that a wide variety of dogs may become sick after eating food rich in this particular vegetable for long periods of time. Many common varieties of grain-free dog food are found to contain high quantities of potatoes.

Both potatoes and their stems/leaves contain highly toxic solanine that is poisonous to your pets. You should never feed a dog raw potatoes, and while cooking will reduce the level of this chemical, potential risks still exist. Instead, consider replacing standard potatoes with dog-approved, cooked sweet potatoes.

3. Oregano: Hidden Herb Hazard

Many of us grow oregano (Origanum vulgare hirtum) in our homes and gardens, but rarely are pet owners aware of how dangerous this particular plant is for their furry friends. Thankfully, nature stepped in to make this plant repellent to cats. Their sophisticated noses sense this fragrance at a level 1400% stronger than humans. The consumption of fresh oregano usually causes mild intestinal issues in both cats and dogs.

Additionally, the essential oil made of this plant contains gastrointestinal irritants, such as terpenoids and phenols. Avoid applying this oil to your cat directly since it is poisonous and its ingestion may lead to liver failure.

4. Hibiscus: What Pet Owners Need to Know

While many hibiscus varieties are considered safe, some types of hibiscus can be poisonous to pets. The Rose of Sharon (Hibiscus syriacus) is particularly concerning for pet owners, as this hibiscus variety can be toxic to both cats and dogs.

For Dogs:

• Most common hibiscus varieties are generally safe
• Rose of Sharon can cause digestive issues if ingested
• Symptoms include nausea, diarrhea, and vomiting
• Severity depends on amount consumed

For Cats:

• Both blossoms and stems of Rose of Sharon are poisonous
• Can cause digestive upset and discomfort
• Monitor cats around all hibiscus varieties
• Remove fallen flowers and leaves promptly

If you're growing hibiscus in your garden or home, take these precautions for your pet:

• Research your specific hibiscus variety before planting
• Keep indoor hibiscus plants out of pets' reach
• Clean up fallen flowers and leaves regularly
• Consider fencing off garden hibiscus plants
• Watch for signs of plant chewing or ingestion

Contact your veterinarian immediately if you suspect your pet has consumed toxic hibiscus parts. While most cases are mild, prompt treatment ensures the best outcome for your pet.

Frequently Asked Questions About Hibiscus and Pets

Are all hibiscus plants poisonous to cats and dogs?

No, not all hibiscus plants are poisonous. While most common hibiscus varieties are considered non-toxic, the Rose of Sharon (Hibiscus syriacus) can be harmful to both cats and dogs. For dogs, ingestion can cause digestive issues, while for cats, both the blossoms and stems can be poisonous.

What happens if my dog eats hibiscus flowers?

If your dog eats Rose of Sharon hibiscus flowers, they may experience nausea, diarrhea, and vomiting. Most cases are mild, but the severity depends on how much was consumed. Other hibiscus varieties typically cause minimal to no issues.

Are hibiscus leaves toxic to pets?

The leaves of most hibiscus varieties are generally safe, but Rose of Sharon hibiscus leaves can cause digestive upset in both cats and dogs. For cats, the leaves pose a higher risk than they do for dogs.

5. Oleander: A Beautiful but Dangerous Flower

A few years ago, I brought oleander (Nerium oleander) seedlings from Greece. I have always adored that flower and wanted to grow it in my garden, but someone told me that it could hurt my pets. 

I learned that all parts of the oleander are highly toxic, and even small amounts may cause several health issues to a variety of species including dogs, cats, and even humans. These plants, especially the variety with red flowers, contain cardiac glycosides, which cause hypothermia, slow heart rate, arrhythmias, severe vomiting, lethargy, and tremors. In some cases, it can lead to death, though this is quite uncommon.

For several reasons, most people have never heard how dangerous this plant can be. This plant primarily grows in California and Hawaii, so most pet owners in the remainder of the country are unfamiliar with its characteristics. Thankfully, for most pets oleander is unattractive. 

If you plant or have this flower growing nearby, always monitor your pets so you can enjoy the fragrance and beauty of this exotic plant without worry.

6. Marijuana: The Pet Exposure Risk

Pet poisoning by marijuana (Cannabis sativa) is one of the most common intoxications seen in veterinary practice, especially in dogs. Due to an increased level of cannabinoid receptors in the canine brain, they are particularly vulnerable. For both cats and dogs, most are exposed by nibbling dried leaves, consuming edibles and/or inhaling second-hand smoke.

In Colorado, a state with legalized marijuana, within five years, two veterinary hospitals noticed that the frequency of marijuana poisoning in dogs has increased four times since the legalization legislation was passed.  

Ingesting these plants in any form may cause depression of the central nervous system and problems with coordination in your pet. In most cases, the animal will experience dilated pupils, increased heart rate, troubles with regulating temperature, vomiting, diarrhea, seizures, tremors, and even coma.

7. Tomato Plant: A Garden Safety Concern

Common tomatoes (Lycopersicon spp) and its entire plant are poisonous for both cats and dogs. The unripe fruit, stems, and leaves contain alpha-tomatine and the same glycoalkaloid solanine as potatoes. These parts of the plant may cause intoxication when eaten in a considerable amount. Fortunately, poisoning by tomato plant is not typically fatal.

Common symptoms include weakness, drowsiness, stomach pain, slow heart rate, and difficult breathing. Ripe tomato fruits themselves won't cause any problems in most cases.

The ASPCA (The American Society for the Prevention of Cruelty to Animals) provides long lists of plant poisonous to both cats and dogs. Make sure to learn more about the hidden dangers that might be in your own home. The best way to protect your pet from poisoning is to check plant lists before adding to your pet food or garden.

About the Author

My name is Emily Jackson. I am a writer, translator, veterinarian, humanitarian, and a passionate traveler. After playing with white bears and elephants in the Belgrade ZOO and dealing with Rabies virus in the Institute Pasteur, I enjoy writing. My five beasts are my ultimate love, including three cats (Clementine, Josephine, and Sophio) and their 'mom' American Stafford Terrier (Malena).