Page 68 - The Mini Horse Magazine 2023 No 1

Water hemlock Red maple

(Cicuta spp.) trees
(Acer rubrum)

INFORMATIVE Also known as: Spotted water hemlock ID: A medium-sized tree with leaves that are

green in the spring and summer, with shallow
ID: A perennial weed with erect hairless stems
notches, bright red stems and a whitish
that can grow to six feet from clusters of fleshy
underside; in fall, the leaves turn bright red.
roots. The stems are hollow and branching,
thicker at the base. Leaves are elongated and
trees, and becomes dark and broken on older
toothed, and the small white flowers form The bark is smooth and pale gray on young
flat, umbrella-shaped clusters at the ends of trees.
branches. The danger: Ingestion of fresh, growing red
maple leaves seems to do little or no harm, but
The danger: Water hemlock is considered one
of the most toxic plants. All parts of the plant when the leaves wilt they become extremely
contain a cicutoxin alkaloid that affects the toxic to horses. Access to wilted leaves is
central nervous system, but the toxin is most most common after storms, which may cause
concentrated in the root. Because cattle are branches to fall into pastures, or in the autumn
more likely to pull up and consume the root, that when the leaves fall and are blown into
species is considered most at risk of poisoning, grazing areas. The toxins in wilted red maple
but horses have also been known to browse leaves cause the red blood cells to break down
the plant; less than a pound of the leaves and so that the blood can no longer carry oxygen;
stems can be fatal. The toxin levels in the leaves the kidneys, liver and other organs may also be
and stems diminish as the plant ages during damaged. As little as a pound or two of leaves
the growing season, and additional amounts can be fatal.
of toxin are lost when the plant is dried, but Signs: Depending on how many leaves were
water hemlock is never considered safe for eaten, signs can appear within a few hours or
consumption. Most animals will avoid the plant. as long as four or five days after consumption.
Signs: The toxins affect neurons primarily Signs include lethargy; refusal to eat; dark red-
within the brain, causing various signs, brown or black urine; pale yellowish gums and
including excessive salivation, dilated pupils mucous membranes at first, advancing to dark
and nervousness, progressing rapidly to muddy brown; increased respiratory rate; rapid
difficult breathing, degeneration of the heart heart rate; dehydration.
and skeletal muscles, seizures and convulsions; What to do: The only treatment is the
death usually results from respiratory paralysis. administration of large amounts of intravenous
Signs of poisoning appear within an hour of fluids and possibly blood transfusions. Recovery
ingestion, and death typically follows within depends on how many leaves were consumed
two to three hours. and how promptly the horse receives care.

What to do: Supportive care initiated before the Special note: Research indicates that the leaves
convulsions begin can offset the worst effects of of at least two related species—the silver
the seizures, but horses who survive are likely and sugar maples—may contain the same
to have experienced permanent damage to the toxic elements as red maples, but in less toxic
heart and skeletal muscles. amounts.

68 | Miniature Horse Magazine • Issue 1/2023