TOXICITY
Black walnut trees are considered toxic but are
different from most other plants considered toxic.
They are generally safe to livestock with the
notable exception of the horse. Affected mostly
by standing in shavings containing black walnut
chips, in some instances, pollen from the walnut
tree in the spring can affect horses by causing an
allergic reaction and if the hulls are eaten, can
potentially cause kidney damage.
EQUINE Health
48 www.EliteEquestrianMagazine.com
EE
BLACK WALNUT
is the only way to assure black walnut laminitis never occurs.
Shavings made from black walnut bark/wood are
generally darker and will differ from the normal pine color.
If shavings are obtained from a local lumber yard, wood
mill or saw mill, make sure the owner is aware that they
cannot use black walnut wood for horse shavings. Manufacturers
sometimes use black walnut in the manufacture
of wood pallets. These are often then ground up for shavings.
Black walnut in also being increasing used for mulch
so avoid using wood intended for mulch use. Escalating
use of black walnut for products both domestic and internationally
make the risk even greater as the trackability
becomes harder if not impossible to follow. Generally,
know your dealer/supplier and make sure they know the
importance of accidently exposing a horse to black walnut
shavings even in small portions.
An ounce of prevention is well worth it. Know what is in
those stall shavings.
BBlack walnut trees (Juglans nigra L) have a dark
brown deeply furrowed bark which makes them
distinctive when seen in pastures or along fence
rows. The leaves are long and pointed and perhaps
the most obvious characteristic is the actual
nut that is contained within a green leathery hull
that generally drop in the fall. Not only are the
hulls potentially toxic if eaten, but walking over
a bed of these hulls beneath the tree can prove
hazardous to anyone’s walking and balance ability.
Toxicity to horses primarily starts to occur if black
walnut wood makes up anywhere between 5-20% (by
weight) of the shavings or sawdust in the stall. If exposed,
horses will begin to show clinical signs within hours of contact
if the concentration is on the higher side and within
24-48 hours if on the lower side on concentration.
Clinical signs include but not limited to stocking up, soft
tissue swelling (edema) in the limbs, reluctance to move,
stiffness, elevated heart and respiration rates, and even
neck/chest swelling. Continued exposure leads to laminitis
and founder. The condition is called black walnut laminitis.
Laminitis results from the disruption of blood flow to the
laminae within the hoof. These structures secure the coffin
bone to the hoof wall. Any inflammation in the laminae
can weaken that bond allowing the coffin bone to eventually
rotate and the hoof wall to separate. Although laminitis
and founder are used interchangeably, founder usually
refers to a chronic long-term condition associated with the
rotation whereas laminitis refers to a sudden initial attack.
The treatment for black walnut laminitis is similar to laminitis
of a different cause. The swelling is reduced by cold hosing
numerous times a day, anti-inflammatory meds (et al) on
board, and alleviation of any pressure on the horses hoof
(e.g. sand stalls, Styrofoam pads or commercially made
booties, etc.) and stall rest. Veterinary intervention immediately
is mandatory.
PREVENTION
/www.EliteEquestrianMagazine.com