Page 949 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Poisonous Plants of the Europe Chapter | 62 901

VetBooks.ir NERIUM OLEANDER (APOCYNACEAE Toxicity
FAMILY)
All parts of the plant contain the toxic alkaloid aconitine,
with the highest concentration in the tubers (roots) and
Common Name: Oleander
Alkaloid content and composition varies throughout the
Nerium oleander is a very common ornamental plant in seeds and lower amounts in the leaves and stems.
Mediterranean areas of Europe; it is also grown in tem- year. The alkaloid content is highest when plants are
perate climates in conservatories and greenhouses. N. ole- flowering (June and July). Horses, donkeys, and goats
ander is a large ornamental evergreen shrub. The long, are more sensitive to aconitum than sheep. The plant is
pointed leaves are oblong and contain a prominent midrib. not usually eaten (acrid test), and field poisoning is
Large clusters of white, pink, or red flowers appear at the uncommon. Aconitine may also be present when forage
end of the branches in summer. It is particularly abundant or hay are contaminated by it.
on sandy soils near the coast. It is widely cultivated and
used as landscaping along roadsides and edges of woods Clinical Presentation
and in lawns and gardens. The clinical signs produced by this plant include vomit-
ing, colic, bradypnea and dyspnea, muscular weakness,
paralysis, pupillary dilatation (mydriasis), and death.
Toxicity
Death is due to asphyxia, and the postmortem findings are
All parts of N. oleander contain very toxic cardiac glyco-
those associated with suffocation. The lesions are not spe-
sides (oleandrin, digitoxigenin, neriin, folinerin, and rosa-
cific, usually appearing to be gastric and renal congestion
genin) that apparently exert a digitoxin-like effect
(Lorgue et al., 1996).
(cardiotoxic potential) (Langford and Boor, 1996). Toxins
may also be inhaled in smoke when plants are burned.
Human poisoning occasionally occurs from eating hot PTERIDIUM AQUILINUM LOR PTERIS
dogs roasted on sticks from nearby oleander plants. This AQUILINA L (POLYPODIACEAE FAMILY)
extremely toxic plant can poison livestock and humans at Common Name: Bracken Fern
any time of the year. The lethal dose in horses, donkeys,
and calves is 30 50 mg/kg BW (Oryan et al., 1996). Pteridium aquilinum is also classified by some authorities
as three separate species, P. aquilinum, P. esculentum,
and P. yarrabense.
Clinical Presentation
It is distributed throughout all European countries and
Severe gastroenteritis, diarrhea, abdominal pain, sweating, on every continent of the world. Bracken fern is most
and weakness are the usual symptoms. These signs appear common in woods, old fields, waste places, and roadsides,
within a few hours after eating the leaves. Cardiac irregu- particularly on relatively dry sites. P. aquilinum is
larities are common, often characterized by increased regarded as a potentially serious threat to the health of
heart rate. However, a slower heart rate is often detected both animals and man. Poisoning is common in places
in the later stages. In comparison with other species, tur-
where P. aquilinum grows naturally.
key poults have not been found to be very sensitive to
Oleander.
Toxicity
In poisoning by P. aquilinum, a polioencephalomalacia
POISONOUS PLANTS AFFECTING occurs because these plants contain the enzyme thiami-
THE ANIMALS nase, which inactivates thiamine (Vitamin B 1 ) in cattle,
sheep, and horses; this is called “pteridism”. The thiami-
Aconitum napellus (Ranunculaceae Family) nase hydrolyzes vitamin B 1 , leading to a depletion of vita-
min B 1 and produces a clinical syndrome of thiamin
Common Names: Aconite, Monkshood,
deficiency primarily in horses.
and Wolfsbane Ingestion of the green plant during periods of food
Aconitum napellus has blue or white flowers bilateraly shortage or when dried plant material (dryness does not
symmetrical with a prominent upper hood, which gives reduce toxicity) is mixed in with hay or straw over a pro-
the genus its name. The perennial herb has palmate leaves longed period (15 30 days) is toxic. Toxic effects from
and a tuberous root. Several species are common garden the plant appear to be cumulative, and symptoms may not
plants, but cases of poisoning in European countries are appear until several weeks or months later (1 3 months),
not common. However, it should be remembered that depending on the species of the animal, the amount
these plants are potentially poisonous. ingested, the time of the year, and other factors. Clinical