| BLUE
GREEN ALGAE
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We have long believed our goats spend hours searching
for new and unusual ways to kill themselves. The most
recent – and unique – method they found
at our farm was to ingest toxic blue-green algae.
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The scientific name for blue-green algae is cyanobacteria.
Cyanobacteria are normally unicellular and manufacture
their own food, relying on sunlight for photosynthesis.
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Most aquatic ecosystems (creeks, rivers, lakes, etc.)
contain blue-green algae that may or may not be visible
to the human eye. But when conditions are right, the
numbers can rapidly increase; and “blooms”
(also called scum) can be seen on water surface. These
algal blooms can be toxic to animals.
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British researchers claim the blooms are more prevalent
in late summer and early fall when warm weather is
followed by heavy rainfall then more warm conditions.
Blooms will normally disappear in winter. Canadian
researchers report the blooms appear in the hot summer
months and are more prevalent in the prairies.
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Thomas Morris,
MD, Medical Epidemiologist in North Carolina wrote,
“Cyanobacteria also have lipopolysaccharides
(LPS, similar to compounds found in the cell walls
of Gram-negative bacteria such as Escherichia coli)
which are potent mediators in the mammalian immune
system. Mortality from cyanobacteria is mostly confined
to veterinary reports in pets and livestock that have
drunk water densely packed with algae.” |
There are between 10 (according to British research)
and 50 (according to Dr. Morris) genera of blue-green
algae that are toxic with the most common being Microcystis,
Anabaena, Aphanizomenon, and Oscillatoria. The three
main toxins are endotoxins, neurotoxins, and hepatotoxins.
Endotoxins are primarily irritants which produce allergic
reactions, rashes, and sometimes gastroenteritis.
Neurotoxins cause muscle tremors and nerve damage
while hepatotoxins damage the liver.
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In general, the blooms do not have a long life, usually
disappearing within days. The blooms are associated
with eutrophication, the process of nutrient enrichment
by phosphates and nitrogen. In rare occasions when
conditions remain favorable, the blooms can remain
for months if nutrient levels are high. When cyanobacterial
toxins are discovered in a water system, they can
be removed by using activated charcoal, but chemicals
such as copper sulphate should not be used.
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Per to Dr. Thomas, “Not all cyanobacteria produce
toxins, and even those known to produce toxins are
not always producing the compounds shown to be toxic.”
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These toxins may be colorless, odorless, and remain
in the water for weeks after the blue-green algae
disappears. These toxins are not destroyed by boiling
the water.
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According to the Cooperative Research Centre for Water
Quality and Treatment in Australia, “The first
documented case of an algal bloom causing deaths occurred
in South Australia’s Lake Alexandrina in 1878.
In that case, cattle, pigs and sheep died within hours
of drinking contaminated water.” Since 1878
there have been many other documented incidents of
poisoning – both of wild and domesticated animals.
According to Health Canada, “Animals are not
more sensitive than people to the effects of the toxins;
they are simply not as concerned with the way water
looks or smells before they drink it.”
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Also according to Health Canada, “Death is usually
caused by damage to the liver or to the nervous system,
depending on which toxins were predominant in the
water. Treatments to counteract the effects of cyanobacterial
toxins in animals have not been extensively investigated
to date.”
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When we recently lost
the four goats and had seven additional goats
down due to what we now believe was blue-green algae,
we are convinced the seven goats we saved recovered
because we gave them penicillin orally to kill the
bacteria in their rumen. The area we think was infected
contained runoff water from the hillside where the
goats spend their evenings (and where they spill feed
and release urine and nannie berries). Heavy rains
caused the runoff water to settle in a small depression
just inside the hay field. Weather conditions and
flooding prevented the area from drying and contributed
to the formation of the blue-green algae blooms.
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