Plants and flowers that are toxic to horses
Whether you are planning a garden adjacent to a horse turn-out or exercise
area, thinking of adding some touches to your riding arena, or re-planting a pasture, it is necessary to keep
in mind that the plants and flowers you use must not be poisonous to horses. Even
if the horses are separated from planted areas by some distance, the wind and birds can carry seeds that will end up in the
pastures.
So, determine from the start what is safe in your area and what will achieve your landscaping or gardening objectives.
Click below for a link to a list of resources to find the toxic plants in your area.
And some that are safe too!
“LITTLE KNOWN FACTS”--
A single ounce of oleander leaves can kill a 1000 pound horse—it has an
effect similar to digitalis in human on the heart. Plant that grows wild in many areas of N. America, and used in containers. (Several links, including Purdue)
Needles from the evergreen Yew--whether dead or alive-- can cause immediate sudden death. Yews are often used in containers, so avoid for decoration of rings, etc.
(Several links including Purdue)
Johnson grass contains cyanide in leaves and stems. (Purdue link)
Toxic levels of nitrates
can accumulate in Johnsongrass following heavy fertilization or drought and result in toxicosis which be confused with cyanide
poisoning
(Ohio State info)
Many species of cherry
and peach trees are poisonous--once eaten, they produce cyanide poisoning in the digestive tract. Does seem to affect
ruminant animals more than horses, however, it can result in death within an hour. Includes eating of wilted leaves.
(Ohio State)
If eaten by horses, St. John's-Wort may cause photosensitization, since this weed contains black dots composed by hypercin,
a pigment that is absorbed by the body and activated by exposure to sunlight. Ingestion can result in a condition in which
patches of white or light-coloured skin become seriously sunburned under normal exposure to sunlight (several links
including Canada).
Horses eating
large quantities of bracken fern show signs of acute poisoning related to vitamin B1 deficiency (Ohio state)
Lupine flowers--grow wild and are popular
for gardens. Causes breathing problems, can end in coma and death (several links including Purdue)
Black walnuts-trees can cause founder
(stablemade link)
Red maple tree leaves,
fallen leaves, wilted leaves--cause poisoning in horses, and only for horses. Dried leaves remain toxic for 30 days. Can result
in coma and death.(Ohio State link)
SAFE PLANTS--
Two safe plants are crepe myrtle and red phototip. (TX A&M link)
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GENERAL INFORMATION
Horse
Poisoning from Oregon State
University
. Poisonings are most likely to occur with very young animals or animals newly brought into the area.
2.
Generally, livestock do not graze toxic plants in a pasture as long as there is abundant, palatable feed. (Tall larkspur and
lambsquarters are exceptions.)
3. Examine pastures in August. Weedy species left untouched are either toxic, unpalatable
or thorny.
4. Most poisonings occur in hay, so check hay closely for weeds. Starthistle can be a hay contaminant from southern
or eastern Oregon.
5. Foxtail Barley and Medusahead cause mechanical
injuries.
6. Lambsquarters and Amaranth are nitrogen accumulators.
7. The corn family foliage, when frosted or drought
stressed, is toxic to horses.
8. Blister beetles are very toxic to horses and are sometimes found in hay. There are many
kinds of blister beetles that feed on hay and pasture crops.
9. Camelids have other toxin problems.There are many poisonous
plants that may be toxic to livestock and horses that are not referenced on this list.
Do not assume a plant is not toxic just because it is not listed here.This material is provided as information
only and is not to be used for the home treatment of animals.
Please contact your veterinarian or poison control if poisoning is suspected.
For further information, the Cornell University website contains many links to information on poisonous plants, http://www.ansci.cornell.edu/plants/comrest.html
Authors: Ross Penhallegon, Pat Patterson, Larry Campbell, Pete Schreder
OSU/Lane County
Extension Service
Revised March 2002
last updated July 16, 2003
PLANT TOXICITY in HORSES
FROM the Canadian Ministry
Horses will usually avoid eating poisonous plants (they don't taste
very good) as long as there is an abundant supply of good quality hay or pasture available. However, faced with no pasture
or hay, a horse might decide to sample one of the poisonous weeds still left standing in the field.
The best medicine for dealing with poisonous plants is ... PREVENTION.
- Ensure that horses on pasture have adequate
hay and/or pasture so that they won't have to resort to eating poisonous weeds.
- Avoid overgrazing, if no supplemental hay is
provided.
- Learn to recognize poisonous weeds and control
them by pulling or by use of commercially registered herbicides.
- Examine your hay for unwanted plants.
