Plant poisonings and mycotoxicoses
Author: Prof Christo Botha
Licensed under a Creative Commons Attribution license.
Southern Africa is well known for the diversity and
Too often plant poisonings are a grey area in the
beauty of its flora. It is perhaps ironical, but not entirely
experience of veterinarians from abroad who find
unexpected, that the subcontinent should also be
themselves in diagnostic or research laboratories in
‘blessed’
Africa.
with
a
possibly
unequalled
variety of
poisonous plants and toxic fungi.
The importance of poisonous plants and fungi to the
livestock industry of Africa cannot be over-estimated.
About 600 indigenous poisonous plants are known to
occur in southern Africa alone. In this part of the world,
where livestock are traditionally kept under extensive
conditions on veld that is frequently denuded by
droughts, overstocking and uncontrolled fires, the
animals are often forced to eat poisonous plants which
they would normally avoid. Devastating outbreaks of
poisoning have been reported under such conditions,
for instance during 1926 and 1927 about 600 000
sheep died of plant-induced photosensitization in the
north-western Cape Province and during 1929 and
1930 over one million were killed by Geigeria spp. in
Griqualand West.
Massive losses are still incurred
almost annually as a result of the ingestion of these
and other poisonous plants such as Senecio spp.,
Dichapetalum cymosum, members of the Rubiaceae
that cause gousiekte, and cardiac glycoside-containing
plants. Some authorities estimate that in certain years
10 – 25 per cent of all stock losses in southern Africa
can be attributed to plant poisonings.
It should be borne in mind that, as many of the
poisonous plants of Africa are unknown in other parts
of the world, very little of the knowledge of plant
poisonings gained elsewhere would be applicable here.