Is Black Walnut Toxic to Dogs and Cats? (2026)
Juglans nigra
Advertisement
Quick facts
| Toxic to dogs | Yes |
|---|---|
| Toxic to cats | Yes |
| Toxic to horses | Yes |
| Toxic component | Juglone and, when moldy, tremorgenic mycotoxins |
| Onset of symptoms | Within a few hours for GI signs; neurological signs from mold can appear within hours of eating moldy nuts |
| Indoor / outdoor | outdoor |
If your pet ate this plant
Both lines are staffed 24/7. A consultation fee applies to each. Do not wait for symptoms to appear before calling.
Advertisement
Symptoms in dogs
- Vomiting
- Diarrhea
- Tremors and seizures if moldy nuts were eaten
Symptoms in cats
- Vomiting
- Diarrhea
Advertisement
What to do
Fresh walnut hulls cause mainly GI upset, but moldy fallen walnuts are a more serious concern due to tremorgenic mycotoxins — contact a vet urgently if a dog has eaten moldy walnuts and shows tremors.
Toxic component and mechanism
The toxic component in Black Walnut is juglone and, when moldy, tremorgenic mycotoxins.
What makes this plant different
Fresh Black Walnut hulls cause mainly mild stomach upset, but walnuts that have fallen and sat on the ground long enough to grow mold present a distinctly more dangerous, fast-acting neurological risk from tremorgenic mycotoxins — freshness and mold status matter more than species identification here.
Plant identification
- Scientific name
- Juglans nigra
- Family
- Juglandaceae
- Also known as
- Black Walnut
- Typically found
- outdoor
Pet-safe alternatives
Advertisement
Related plants
Alocasia
Alocasia spp.
Aloe
Aloe vera
Amaryllis
Amaryllis spp.
Ambrosia Mexicana
Chenopodium botrys
American Bittersweet
Celastrus scandens
Last verified: July 2, 2026 · Cross-referenced with ASPCA Animal Poison Control