Purchase the Book
Owners Field Guide to Toxic Plants
ON THE PICTURE BELOW:
For a University of Pennsylvania
Poisonous Plants, click here:
For a Purdue
Of Veterinary Medicine
Poisonous Plants, click here:
a printable PDF of
"A Guide To Plants
That Are Poisonous
helpful links on
trees that are
the pictures & links below:
Colorado State Univ.
Note: When in doubt regarding plantings around your horses, and how safe/unsafe they are, contact your local Cooperative Extension Office and they can help! To locate your closest U.S. Department of Agriculture Cooperative Exension office: CLICK HERE
plants in the U.K.:
- Poisonous Plants and Trees
- That Can Harm Your Horse
of this below are from an article in the
- March, 2001 issue of EQUUS magazine
- By Joanne Meszoly
As praiseworthy as trees are, there are
a few situations where horses and trees
don't mix. In some cases, fruit- or nut-bearing
trees contribute to colics when horses gorge
on their produce. In others, falling branches
or uprooted trees injure nearby horses.
But the gravest dangers arise with the few
tree species that are toxic enough to sicken
or kill horses.
Of the nonornamental native trees, the
most deserving of the skull-and-crossbones
warning are those that produce cyanide in
their wilted leaves. Cyanide suffocates
animals by blocking oxygen transport via
the red blood cells. The red
maple (Acer rubrum) is one
such tree whose leaves are harmless most
of the year until wind damage or seasonal
change causes them to fall from the tree
and wilt. Red maple leaves have serrated
edges and can turn either red or yellow
in the fall. "There are other trees
that shed red leaves in the fall, but the
red maple has some distinctive features,"
says Anthony Knight, BVSc, MRCVS, who specializes
in toxic trees and plants at Colorado State
University. "The underside of the red
maple leaf tends to be silvery in color."
Signs of poisoning, including lethargy,
discolored urine and darkened gums, may
not appear for four days.
Equally toxic are cherry
(black cherry, chokecherry, and fire cherry)
peach and plum
trees, all members of the
Prunus species. These leaves also produce
cyanide when wilted, affecting horses within
a few hours of ingestion.
To be safe, remove these deadly trees
or relocate horses away from pastures bordered
by or containing them. In general, horses
are not likely to eat leaves or any other
tree parts unless they are quite hungry.
However, when curiosity or boredom spurs
exploratory bites, the horse may ingest
enough of the deadlier species to do harm.
The following trees have no place in
horsekeeping areas because of their toxicity
or potential for causing digestive distress.
They are listed below in order of the
risk they pose to horses, starting with
the most hazardous. For more information
and pictures of many of the below, click
on the name:
Some plants and trees that may be present
in your pastures or fields could be dangerous
or even deadly to your horse. You may see
these innocent looking plants every day
and not even know that they pose a threat!
If you suspect that you may have any of
the following around you, you should consult
with a vet knowledgeable in toxicology and
get them removed before your horse finds
First and foremost is the red
maple tree. Yes that's right,
the common red maple. If ingested, the leaves
of the maple contain substances that can
cause a breakdown of your horse's red blood
cells leading to severe problems. If you
have any red maples in your pastures, get
them removed immediately and if you don't
have them, then definitely don't plant any.
Laurel is another plant to
avoid. Yes for those in PA, our state flower
can be toxic to horses.
need to be avoided as well. These 3 plants
contain toxins that can cause diarrhea,
weakness, impaired vision, and heart problems
and can be deadly within 1-2 days.
is a toxic plant that we've all seen and
chances are your horse may have too. Worse
yet, he may think it's a tasty treat. Unfortunately
milkweed can cause seizures, lack of coordination
and colic in horses and may lead to death
1-3 days after ingestion. One more complicating
factor is that milkweed is still toxic after
drying so if any of it accidentally winds
up in your horse's hay, they could be in
big trouble. Please be certain that
you know where your hay is coming from.
You may be a bit more familiar
with the need to avoid water
hemlock as it is quite toxic
to humans as well as horses. It is commonly
found near streams or in swampy, wetland
areas, so be very cautious about letting
your horse graze in these regions if you
don't know what types of plants are out
there. It can cause violent seizures and
muscle twitching closely resembling tetanus.
Also causing similar signs
hemlock. Poison hemlock can
be found in fertile, moist soils in areas
such as woodlots, fencerows, and waste areas.
Two other toxic plants found
in similar types of environments are sorghum
grass and wild
cherry trees, which contain cyanide.
In PA and other parts of the northeastern
and eastern part of the US white snakeroot
is apparent. White
snakeroot is often found
in forest soils or at the interface between
forests and croplands. Again the plant is
toxic both fresh and dried, so watch out
for your hay. Horses can get very depressed
or weak if they have eaten this plant, and
may show signs similar to congestive heart
Big warning on this next one... black
walnut trees. These are very
common and shavings or sawdust from these
trees sometimes get used as horse bedding.
Interestingly, ingestion is not the problem
here. Instead, this will likely cause laminitis
in your horses hooves. Additionally, some
parts of the hoof can become necrotic. If
your horse is having problems with laminitis,
you may want to inspect your bedding carefully
for black walnut shavings. Black
locust trees are also particularly
toxic to horses and some types of oak
trees can be as well, although
more so to sheep and cattle. Finally yew,
although not commonly grown freely in pastures
can be a serious problem if carelessly discarded
into a pasture or if animals escape and
gets access to landscaped areas.
This is by no means a complete list and
I would recommend that any horse owner buy
a book containing a comprehensive listing
of toxic plants and trees to make sure that
your horse doesn't have access to any of
them. As I mentioned many of these toxic
plants could kill within 1-3 days of being
eaten, so avoidance is much better than
trying to cure the problem after it happens.
As always if you suspect your horse may
have eaten a toxic plant or tree, consult
your veterinarian immediately. I sincerely
hope that this helps to make your horse's
life a safe and happy life!
READ THIS REGARDING OAKS AND ACORNS:
Beware: Acorns Can Cause Colic and Founder
Oaks and their toxicity to horses
Acorns and Stomaches
Acorn Toxicity in Horses
Another link for information on plantings and weeds/grasses that are toxic to horses: CLICK HERE
And here's another excellent article on the subject: CLICK HERE
Note: When in doubt regarding plantings around your horses, and how safe/unsafe they are, contact your local Cooperative Extension Office and they can help! To locate your closest U.S. Department of Agriculture Cooperative Exension office: CLICK
FOR MORE RESOURCES ON TOXIC-TO-HORSES PLANTINGS, SEE LEFT SIDEBAR ON THIS PAGE