Oak Toxic?

Updated 2026-03-06| 3 min read| 3,260 found this helpful

Quercus species

Oak is confirmed toxic to horses, but its toxicity risk to cats and dogs has not been formally established

The primary toxic compound in oak is gallotannin, present in leaves, bark, and acorns of the plant

Ingestion of oak plant parts or acorns can cause digestive distress, urinary issues, jaundice, and potentially digestive tract obstruction in susceptible animals

FAQ

Is Oak toxic to Humans?

No confirmed human toxicity data available; seek immediate medical care if large quantities of oak parts or acorns are ingested (Unknown)

Is Oak toxic to Cats?

Toxicity to cats is unconfirmed, no specific clinical signs have been formally documented (Unknown)

Is Oak toxic to Dogs?

Toxicity to dogs is unconfirmed, no specific clinical signs have been formally documented (Unknown)

Is Oak toxic to Horses?

Abdominal pain, constipation followed by diarrhea (occasionally bloody), depression, frequent urination, discolored urine, jaundice; acorn ingestion may cause digestive tract obstruction (Moderate)

Not sure which plant? Snap a photo to ID in 1 secondGet App

Toxicity Details

Humans

Unknown

No confirmed human toxicity data available; seek immediate medical care if large quantities of oak parts or acorns are ingested

Cats

Unknown

Toxicity to cats is unconfirmed, no specific clinical signs have been formally documented

Dogs

Unknown

Toxicity to dogs is unconfirmed, no specific clinical signs have been formally documented

Horses

Moderate

Abdominal pain, constipation followed by diarrhea (occasionally bloody), depression, frequent urination, discolored urine, jaundice; acorn ingestion may cause digestive tract obstruction

Toxicity Snapshot

Toxic PartsLeaves, bark, acorns, and all green growing plant parts of Quercus species

Exposure RoutePrimary exposure route is ingestion of toxic oak plant parts; casual dermal contact poses no known toxicity risk

Toxic CompoundsGallotannin

First Aid & Prevention

First 30 Minutes

• Remove all remaining oak plant material or acorns from the exposed animal's access and mouth if they are conscious
• Do not induce vomiting unless explicitly instructed to do so by a licensed veterinarian
• Collect a sample of the ingested oak material or acorns to share with veterinary staff for confirmation

Contact Vet Immediately

• A horse has ingested any quantity of oak leaves, bark, or acorns
• Any animal shows symptoms including abdominal pain, abnormal bowel movements, discolored urine, or jaundice after possible oak exposure
• The animal shows signs of digestive obstruction such as unproductive retching or severe abdominal distension

Prevention

• Keep oak trees, fallen leaves, and acorns out of reach of pets, and remove oak debris from horse grazing pastures
• Educate horse owners and pet caregivers about the confirmed toxic risk of oak to horses to avoid accidental ingestion
• Regularly clear fallen acorns and oak plant debris from yards, paddocks, and grazing areas used by animals

Treatment & Prognosis

• Veterinarians may administer activated charcoal for decontamination in cases of recent, uncomplicated ingestion
• Supportive care including fluid therapy, pain management, and gastrointestinal support will be provided based on presented symptoms
• Surgical intervention may be required if acorn ingestion causes complete digestive tract obstruction

Emergency? Open PlantFun for real-time AI guidanceGet App

Professional Toxicology

Scientific NameQuercus species

AliasesOak tree、Acorn tree

Toxicity Grade

HumansUnknown

CatsUnknown

DogsUnknown

HorsesModerate

Target Organs

Gastrointestinal tractLiverKidneys

Mechanism of Action

• Ingested gallotannins cause direct irritation to the gastrointestinal tract, followed by systemic damage to liver and kidney tissue

• Large, hard acorn fragments can cause physical blockage of the digestive tract even at low ingestion quantities

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: Moderate toxicity reported, ingestion of large oak quantities may cause weight loss, kidney damage, and digestive symptoms matching those seen in horses

Sheep: Low to moderate toxicity, large ingestion of oak plant parts may lead to gastrointestinal upset and mild liver damage

Confusion Risk

The following plants look similar and may be confused:

American Chestnut Castanea dentata

Both belong to the Fagaceae family with similar serrated leaf shapes; chestnut leaves are longer with more pronounced sharp teeth, while most oak leaves have characteristic lobed structures

American Beech Fagus grandifolia

Both are common deciduous Fagaceae trees; beech leaves have a fine, soft texture and distinct parallel veins, unlike the thicker, often lobed leaves of oak species

Use PlantFun to scan and avoid misidentificationGet App

Related Toxic Plants

Black Oak

Quercus velutina

Moderate toxicity, confirmed toxic to horses with the same gallotannin toxic principle as other oak species

European Beech

Fagus sylvatica

Low toxicity, ingestion of raw beech nuts may cause gastrointestinal irritation and neurological symptoms in severe cases

Horse Chestnut

Aesculus hippocastanum

High toxicity, ingestion of seeds, leaves, or bark causes severe gastrointestinal distress and neurological damage in all animal species

Download PlantFun App

Identify, grow and care for plants effectively!

Instant Plant ID

Take a photo to quickly identify plants.

Smart Care Reminders

Generate watering and care schedules.

Toxicity & Disease Diagnosis

Identify toxic plants and pests with treatment advice.

Data Sources

1. ASPCA Animal Poison Control

This information is for reference only and does not constitute medical advice. If ingestion or poisoning is suspected, seek medical or veterinary attention immediately.

View Full Plant Wiki