Black Walnut
Juglans nigra
Horse
Severe
Any suspected ingestion is an immediate veterinary emergency. Bedding containing only 10 to 20% black walnut shavings causes laminitis in less than 24 hours.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Symptomatic and supportive treatment for laminitis.
- Time to signs
- Less than 24 hours
- Prognosis
- Grave. Mechanical laminitis can lead to the rotation of the third phalanx, potentially requiring euthanasia of the horse.
- IMMEDIATELY remove the horse from its bedding.
- Thoroughly wash its feet and legs with cold water.
- Call a veterinarian for laminitis treatment.
Its ID card
- Height
- Jusqu'à 30-40 mètres
- Flowering
- Spring (April-May in North America, may vary in Europe)
- Toxic parts
- Wood shavings (bedding), roots, nut husks, bark.
- Toxin
- Juglone (and other poorly identified toxins that trigger inflammation).
- Habitat
- Parks, forest plantations, large estates.
- Soil indicator
- Rich, deep, and well-drained soils.
- Regions
- Europe (Parks and forests), Native to North America
- In hay
- Not reported
- Palatability
- Low. The danger is primarily dermatological/contact via the hooves, although ingestion exacerbates symptoms.
When the risk rises
All year round (via bedding). Autumn (falling fruits).
Spotting it in the field
Common Walnut (Juglans regia, less toxic but should still be avoided). — smell : bark and leaves can release an acrid odor when crushed.
- Large tree.
- Very dark, deeply fissured bark.
- Compound leaves with numerous leaflets.
- Large, round nuts with a very rough green husk.
Signs to watch for
Acute toxicity (from prolonged contact with bedding)
Dose : Bedding containing 10-20% black walnut shavings.
- Acute, fulminant laminitis (prostrate horse, rocking back on heels)
- Hot and edematous limbs
- Lethargy and severe depression
- Mild colic
- Strong digital pulse
Who is affected
Other species : Juglone inhibits the growth of many other plants under the tree. Toxic to dogs (moldy husks = neurotoxic).
In pregnant mares : low directly, but extreme pain can induce abortion.
Getting rid of it
Method : Remove the tree or manage wood shavings. If the tree is present, avoid using its shavings as bedding. Juglone is present in the roots and bark.
- Never use black walnut wood shavings for equine bedding.
- Identify and keep horses away from areas where black walnut is present, especially if shavings are used.
- If black walnut is present in a pasture, fence off the root zone to prevent access.
Frequently asked questions
Can Equio identify Black Walnut from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Black Walnut dangerous in hay?
Hay risk is not always reported for this entry, but suspicious forage should still be isolated until checked.
This page is informational. If ingestion is likely, if signs appear, or if the horse is fragile, contact a veterinarian immediately.