Black walnut: a toxic horse bedding

Plant characteristics

• Large tree with a big, round and symmetrical canopy appearance.

• Leaves consist of 11 to 13 long, toothed leaflets.

• Dark brown to nearly black, deeply furrowed bark.

• Flowers appear in April through June.

• Dark shavings.

Black walnut grows in the eastern half of the U.S., except at the northern border.

Black walnut prefers moist, well-drained soils, especially along streams and rivers. These trees usually grow scattered in mixed deciduous forests.

Toxicity

Black walnut shavings are toxic bedding for horses. The innermost wood of the black walnut causes toxicity after oral or skin contact.

Bedding containing as little as 20 percent fresh black walnut shavings, made from old or new wood, can cause toxicity. Black walnut shavings are commonly supplied by furniture manufacturers.

Signs of illness

Within a few hours of toxicity, the following signs occur.

• Depression

• Stocking up

• Warm hooves

• Acute laminitis (founder)

• Stiff gait

• Reluctance to move

As toxicity progresses, you may see,

• Flared nostrils

• Colic

• Swelling in the neck and chest areas

• High heart and breathing rates

• High body temperature

• Laminitis may result in coffin bone rotation in severe cases

Treatment

Signs of toxicity often subside within hours of removing black walnut shavings. A mild sedative and mineral oil may be helpful in some cases; nonsteroidal anti-inflammatory drugs are often used.

Control

Don’t use black walnut shavings for horse bedding.