Page 951 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Poisonous Plants of the Europe Chapter | 62 903

VetBooks.ir (Warren and Waughan, 1985). The rumen contains acorns ers near the base, and pistillate flowers are mostly near
Flowers are green and inconspicuous; staminate flow-
large
fatal.
is
frequently
numbers.
Evolution
in
the top of a small panicle. The fruit is a three-lobed cap-
Hemorrhagic lesions of the gastrointestinal tract, nephri-
tis, and perirenal edema may be important. sule with a soft, spiny exterior, 1.5 2 cm long. There are
three seeds per capsule. Seeds are shiny, grayish brown
mottled with reddish brown, and 10 mm long and 6 or
ROBINIA PSEUDOACACIA
7 mm wide. Seeds resemble engorged ticks and usually
(PAPILIONACEAE FAMILY) tree in a somewhat spiny pod.
Common Names: False Acacia, Locust Tree
and Black Locust Tree Toxicity
The poisonous principle is a phytotoxin called ricin. In
Robinia pseudoacacia is a large ornamental tree with
Europe, the plant is commonly planted not only as an
alternate, compound leaves and unbranched spines resem-
ornamental but also in vegetable gardens to repel moles.
bling rose thorns. It is often used in landscaping and
Horses are most susceptible to poisoning, but all livestock
grows wild. Black locusts growing near pastutes can hang
and humans can be affected. All parts of the plant are
over fences and drop seedpods into a pasture that may be
toxic, especially the seeds. Toxicity is seen most often in
bundled in hay. This plant has been cultivated and is a
spring and summer.
common tree in dry woodlands, old fields, roadsides,
fence rows, and pinelands, particularly in clay soils,
although it can be found in sandy soils. Clinical Presentation
Animals are most often poisoned when feed grains have
Toxicity become contaminated with the castor bean seeds.
Depending on the amount consumed, symptoms appear
Toxic principles include the phytotoxin robinin and the
from several hours to days after animals consume the
glycoside robitin (emetic and purgative) found throughout
toxin. Violent purgation in the form of straining and
the plant, although the flowers have been suggested to
bloody diarrhea is the classical sign. Other signs are dull-
contain the toxic principles. The toxic parts are leaves
ness, abdominal pain, weakness, trembling, and
particularly wilted ones, young shoots, pods, seeds, and
incoordination.
inner bark. Apparently, the toxin is heat labile, and it pro-
duces gastrointestinal distress. Horses, cattle, sheep, goats,
poultry, and humans may be poisoned by ingesting roots, SENECIO SPP. (COMPOSITEAE FAMILY)
bark, sprouts, seed pods, or trimmings during periods of
drought or food shortage. Horses are most susceptible to Common Names: Ragwort and Groundsel
the effects of Robinia pseudoacacia.
This plant is very common in pastures and agricultural
lands. Ragwort appears to be less common and is peren-
Clinical Presentation nial, while groundsel is an annual and has a hollow stem.
Symptoms include diarrhea, anorexia, weakness, posterior These plants maintain toxicity after drying, so they are
paralysis, depression, mydriasis, loss of appetite, irregular still toxic in baled hay. Plants in this group start as basal
pulse, and difficult breathing. Intestinal problems can lead rosettes. The genus of this family contains more than
to bloody diarrhea. Death is not frequent. Postmortem 1200 species, of which 25 are known to be toxic
lesions are restricted to the gastrointestinal tract. and causes seneciosis. Members of the plant family
Symptoms can appear 1 2 h after ingestion. Mucous include Senecio aquaticus (marsh ragwort), S. jacobea
membranes turn yellow, appendages become cold and (ragwort or tansy ragwort), S. squalidus (Oxford ragwort)
pupils dilate. and S. vulgaris (groundsel). In the United Kingdom, there
have been many reported incidents involving exposure to
ragwort. Ragwort (S. jacobea) is a highly toxic plant that
RICINUS COMMUNIS (EUPHORBIACEAE
grows widely in pastures, as well as on many areas of
FAMILY) waste land, and like the buttercup (Ranunculus spp.), it
often remains ungrazed so long as there is an alternative
Common Name: Castor Bean
supply of feed. However, there is a crucial difference
The plant Ricinus communis has large, palmately lobed between these two plants that renders buttercups relatively
leaves, and it is a robust annual (in southern regions) or harmless (the toxic principle is an unstable chemical that
perennial (in tropics and subtropics regions) woody herb. is not found in hay made from such meadows) while rag-
It is cultivated and occasionally escapes and persists in wort continues to be a major problem to both ruminants
pinelands, waste places, and roadsides. and horses.