Acorns and Oak Trees
Falling acorns are one of the trademarks of autumn, but they can cause problems for curious dogs and, less commonly, cats. Acorns and leaves from the oak tree contain substances that can irritate the digestive system and, in larger amounts, cause more serious illness.
How Acorns Harm Pets
Toxic compounds: Acorns and oak leaves contain tannins, naturally occurring plant compounds that can irritate the stomach and intestines.
Toxicity level: Mild to moderate in most dogs, depending on how many acorns are eaten.
Other risks: Beyond chemical irritation, whole acorns can also cause choking or intestinal obstruction—especially in small dogs.
Most pets that chew on a single acorn or two experience only mild stomach upset. However, frequent snacking on acorns or large ingestions can lead to more significant problems.
Signs of Acorn or Oak Leaf Poisoning
Vomiting
Diarrhea (sometimes with blood)
Loss of appetite
Abdominal pain
Lethargy or weakness
In severe or repeated exposures: dehydration or changes in kidney function
What to Do if Your Pet Eats Acorns or Oak Leaves
Call ASPCA Poison Control immediately at 888-426-4435 for guidance on what to do next.
Do not induce vomiting or give home remedies unless directed by poison control or your veterinarian.
Seek veterinary care, if recommended
Veterinary Care
Most dogs recover well with supportive care. Your veterinarian may:
Give medications to control vomiting and diarrhea
Administer fluids to prevent or correct dehydration
Recommend monitoring for signs of kidney irritation if large amounts were eaten
Take X-rays if an intestinal blockage is suspected
Prevention
Keep yards free of fallen acorns when possible.
Supervise dogs outdoors in heavily wooded or oak-filled areas.
Discourage chewing or playing with acorns as “toys.”
Be especially cautious with puppies, who tend to explore by mouthing objects.
Final Thought
Acorns are a symbol of fall, but they aren’t harmless for pets. Tannins can upset the digestive system, and whole acorns can block the intestines. While small exposures usually cause only mild illness, it’s best to prevent access altogether. If your pet eats acorns or oak leaves, call ASPCA Poison Control first and follow their advice for the safest next steps.
Information adapted and expanded with reference to ASPCA Poison Control.
Gal Chivvis, DVM
