What makes it harmful
tremorgenic mycotoxins (Penitrem A) from mold that grows on walnuts, especially fallen/black walnuts; also juglone in black walnuts
How much is dangerous
The real danger is MOLD: walnuts that fall from trees and sit on the ground grow Penicillium mold, which produces Penitrem A — a neurotoxin that causes tremors and seizures (Merck Veterinary Manual). Fresh English walnuts are less risky but still high in fat (pancreatitis). There is no safe amount of moldy walnuts.
Symptoms to watch for
Mild / early
- • Vomiting
- • Tremors
- • Restlessness
Severe — vet urgently
- • Severe whole-body tremors
- • Seizures
- • High fever
- • Death
What to do if eaten
Tremorgenic mycotoxin poisoning is an emergency — if a dog eats moldy or fallen walnuts and shows tremors, get to a vet immediately. Even without symptoms yet, call poison control.
Frequently asked questions
- Can dogs eat walnuts?
- Dangerous — moldy walnuts can cause seizures. Black walnuts and fallen nuts are the main risk. The real danger is MOLD: walnuts that fall from trees and sit on the ground grow Penicillium mold, which produces Penitrem A — a neurotoxin that causes tremors and seizures (Merck Veterinary Manual). Fresh English walnuts are less risky but still high in fat (pancreatitis). There is no safe amount of moldy walnuts.
- What happens if a dog eats walnuts?
- Symptoms can include vomiting, tremors, restlessness, severe whole-body tremors, seizures, and more. Severity depends on the amount and your dog’s size.
- What should I do if my dog ate walnuts?
- Tremorgenic mycotoxin poisoning is an emergency — if a dog eats moldy or fallen walnuts and shows tremors, get to a vet immediately. Even without symptoms yet, call poison control.
Sources: Merck Veterinary Manual · ASPCA Animal Poison Control · PetMD.
⚠️ For general guidance, not veterinary advice. Toxicity depends on your dog’s size, the amount eaten, and individual sensitivity. Always confirm with your vet for health decisions.