Can Dogs eat Walnuts?
Keep Walnuts Away from Dogs
English (Persian) walnuts in tiny quantities are unlikely to kill a dog outright, but the risk-to-benefit ratio is poor enough that veterinarians universally advise against feeding them. Black walnuts should be treated as outright toxic due to juglone content. Any walnut left on the ground or stored improperly may grow Penicillium or Aspergillus molds that produce tremorgenic mycotoxins capable of causing seizures within hours. Given that safer, genuinely beneficial treats exist, there is no compelling reason to offer walnuts to dogs.
Moderation Is Essential
Walnuts should only be offered to dogs in small, infrequent amounts. Follow the safe feeding guidance and watch closely for any reactions.
Why Are Walnuts Dangerous for Dogs?
Walnuts — dogs.
The walnut family presents two overlapping hazards. First is the issue of species: black walnuts (Juglans nigra) contain juglone, a naphthoquinone compound that is directly toxic to dogs. Even small amounts — a single black walnut kernel or exposure to the hull — have been associated with vomiting, lethargy, and tremors. English walnuts (Juglans regia), the grocery-store staple, do not contain significant juglone, but they are by no means benign. Their very high fat content (roughly 65% fat by weight) can trigger acute pancreatitis in dogs, whose pancreatic enzyme regulation is far more sensitive than ours to dietary fat spikes. A medium-sized dog (around 10 kg) eating just two or three English walnuts in one sitting is ingesting enough fat to provoke gastrointestinal inflammation.
The second — and arguably more dangerous — hazard is mold. Walnuts' oily, porous shells create an ideal microenvironment for tremorgenic mycotoxin-producing fungi, especially Penicillium crustosum. These mycotoxins (primarily penitrem A and roquefortine C) are potent neurotoxins that cause muscle tremors, incoordination, hyperthermia, and seizures in dogs at very low doses. Dogs that scavenge walnuts from the garden, garage, or compost bin are at particular risk because fallen nuts can begin molding within days in warm, damp conditions. There is no reliable way for an owner to determine visually whether a walnut is mycotoxin-contaminated — mold may be internal or microscopic. This unpredictability is a core reason why even 'fresh-looking' walnuts warrant caution.
Black walnuts should be considered toxic regardless of quantity or apparent freshness — juglone is present throughout the nut, hull, and bark. If your dog chews on a black walnut tree branch or hull, contact your vet immediately.
Symptoms & progression
- Vomiting
- Diarrhoea
- Abdominal pain or guarding
- Loss of appetite
- Bloating
- Muscle tremors
- Incoordination / ataxia
- Hyperthermia (elevated body temperature)
- Seizures
- Excessive salivation
- Weakness or collapse
- Hunched posture
- Repeated vomiting 12–24 hours after ingestion
- Painful, tense abdomen
- Lethargy and reluctance to move
- Fever
- Gagging or retching without productive vomit
- Pawing at the mouth
- Sudden distress or restlessness
- Reduced or absent bowel movements
Dose & severity
There is no established 'safe' dose for black walnuts or moldy walnuts — none should be given. For English walnuts, the risk escalates rapidly with quantity and dog size; the table below illustrates why even small amounts are inadvisable.
What to Do If Your Dog Ate Walnuts
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1
Identify the walnut type immediately. Determine whether the nut was a black walnut or English walnut, and whether it appeared moldy, discoloured, or was foraged from outside. This information will critically guide your vet's response.
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2
Call your vet or an animal poison helpline without delay. If your dog ate black walnuts, any visibly moldy walnut, or a large quantity of English walnuts, telephone your veterinarian, the ASPCA Animal Poison Control Center (888-426-4435), or the Pet Poison Helpline (855-764-7661) right away — do not wait for symptoms to appear.
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3
Do not induce vomiting without professional guidance. Inducing emesis at home is appropriate in some walnut ingestion cases (especially recent ingestion of moldy nuts) but should only be done under veterinary instruction and using safe methods. Never use salt, hydrogen peroxide above 3%, or other home remedies.
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4
Watch for neurological symptoms as a top priority. Muscle tremors, incoordination, or seizures after walnut ingestion constitute a veterinary emergency. If these develop, transport your dog to an emergency clinic immediately — tremorgenic mycotoxicosis can deteriorate rapidly.
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5
Monitor for pancreatitis signs over the next 24–48 hours. Even if your dog initially seems fine after eating a moderate amount of English walnuts, watch for vomiting, hunched posture, or abdominal pain emerging the following day. Pancreatitis can be delayed in onset and may require IV fluid therapy, pain management, and hospitalisation.
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6
Secure your garden and compost. If you have walnut trees or store walnuts at home, ensure dogs cannot access fallen nuts, husks, or stored bags. Place compost bins with walnut scraps behind dog-proof fencing — this is an often-overlooked source of mycotoxin exposure.
Safe alternatives
If you want to offer your dog a nutritious, nutty-flavoured snack without the risks walnuts carry, these options are veterinary-approved in appropriate portions.
Rich in protein and healthy fats; widely enjoyed by dogs and safe in small amounts — always check labels for xylitol before offering
Lower in problematic compounds than walnuts; fine as an occasional treat for dogs without weight issues, though still high in fat so portion control matters
A genuinely dog-friendly seed — provides zinc, magnesium, and omega fatty acids, and is sometimes used to support urinary and digestive health
High in vitamin E and linoleic acid; a small pinch as an occasional topper is safe and contributes to coat health
Frequently asked questions
My dog ate one English walnut off the floor — do I need to go to the vet?
Why are black walnuts more dangerous than English walnuts for dogs?
What do tremorgenic mycotoxins from moldy walnuts do to a dog's body?
Can walnuts cause pancreatitis in dogs, and how would I recognise it?
Sources & references
- ASPCA Animal Poison Control Center — Walnut toxicity in dogs, ASPCA Professional toxic plant and food database
- Merck Veterinary Manual — Mycotoxicosis: Tremorgenic mycotoxins (penitrem A, roquefortine), clinical signs and treatment in small animals
- Gwaltney-Brant S, et al. (2018). 'Food hazards for pets.' In: Veterinary Toxicology: Basic and Clinical Principles, 3rd ed., Academic Press
- Pet Poison Helpline — Walnuts and dogs: black walnut vs. English walnut toxicity overview
About the author: Dra. Carmen Ortega
Diplomate of veterinary nutrition focused on species-appropriate diets and preventative feeding, and lead author of our dietary guidance.
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