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Liver FLukes |
The worst disaster of our career as llama farmers was caused by liver
flukes, and a vet who swore we didn't have them.
Over the course of two months, we lost a heart-rending nine female llamas,
many carrying unborn crias.
The animal would appear healthy in the morning, might refuse to get up by
noon, and would be dead by four p.m. We lost females that had gotten
thin as well as females that were in good body condition. The only
clue to impending death would be that the animal's body temperature would go
down - most likely as it went into shock.
We had had problems that winter keeping weight on animals in our female
herd. It didn't seem to matter what we fed, most of the animals were
losing body weight, even those that were previously "easy keepers". However,
other animals seemed fine. We couldn't figure out what was going on.
We found out later that liver flukes interfere with the animal's ability to
process protein, thus causing weight lose.
In camelids, liver flukes are particularly damaging to the pancreas.
One six month old female had a pancreas that had been literally torn apart -
inside her body - before she died.
Another female had extensive damage to her pancreas and had over a gallon of
reddish-brown fluid in her abdomen on necropsy - the fluid would have been
seeping from her pancreas and liver for days before she died. She had
encapsulated liver flukes in her body as well.
In our case, the liver flukes were traced back to a number of animals that
we had brought into our herd in the fall - they liver flukes, which had
invaded our entire female herd over the winter and began killing females
early in the new year.
It was only after the fourth necropsy report found "adult liver flukes" that
our vet at the time decided we should treat for liver flukes - despite the
fact that our symptoms matched those for liver flukes, and long before this
time we had been told by another breeder in Wisconsin that we most likely
had them in our herd, what to look for, and how to treat for them.
Liver flukes can't be found in a normal fecal float, thus they go undetected
many times. The liver fluke has a complicated life cycle - it requires
as snail as an intermediate host, so liver flukes used to be confined to wet
locations - like the entire Pacific Northwest. However, with the
movement of livestock they are now found almost everywhere.
Prevention is simple - worm twice a year - in our case November and February
- with Valbazen, which eliminates liver flukes. If only we had been
given that opportunity, we would have avoided a great deal of heartbreak.
Valbazen is given by mouth, and it is also good for tapeworms, as well as a
number of other types of worms. Don't use it on females within the
first two months of pregnancy as it can cause birth defects.
Below is an article on Liver Flukes. |
Fasciola hepatica
(the sheep liver fluke)
The common name of this parasite, the "sheep liver fluke," is somewhat
misleading since this parasite is found in animals other than sheep
(including cattle and humans), and the parasite resides in the bile ducts
inside the liver rather than the liver itself. This species is a common
parasite of sheep and cattle and, therefore, relatively easy to obtain.
Thus, in introductory biology or zoology courses, it is often used as "THE"
example of a digenetic trematode. This species has been studied extensively
by parasitologists, and probably more is known about this species of
digenetic trematode than any other.
The adult parasites reside in the intrahepatic bile ducts, produce eggs,
and the eggs are passed in the host's feces. After passing through the
first intermediate host (a snail),
cercariae
encyst on vegetation. The definitive host is infected when it eats the
contaminated vegetation. The
metacercaria excysts in the definitive host's small intestine, and the
immature worm penetrates the small intestine and migrates through the
abdominal cavity to the host's liver. The juvenile worm penetrates and
migrates through the host's liver and finally ends up in the bile ducts (view
a diagram of the life-cycle). The migration of the worms through the
host's liver, and the presence of the worms in the bile ducts, are
responsible for the pathology associated with fascioliasis.
Fasciola hepatica is found in parts of the United States (view
distribution), as well as in Great Britian, Ireland, Europe, the Middle
East, the Far East, Africa, and Australia. Fascioliasis in sheep and cattle
results in animals that show low productivity (low weight gain, low milk
production, etc.). Also, in many countries, livers from animals infected
with F. hepatica are condemned as unsuitable for human consumption.
This not only results in a significant economic loss to ranchers and
farmers, but it also results in the loss of an important source of protein.
The infection can be diagnosed by finding eggs in the feces of animals, but
the eggs are difficult to differentiate from closely related species such as
Fasciolopsis buski. Several immunological methods for diagnosis are
available.
Fasciola hepatica egg; approximate size = 140 µm in length.
Fasciola hepatica egg.
Another example of a Fasciola hepatica egg, showing the
operculum. (Original image from:
The Atlas of Medical
Parasitology.)
A stained whole mount of an adult Fasciola hepatica;
approximate length = 20 mm. The internal organs of this species are
characteristically highly branched, thus making it very difficult to
differentiate the various internal organs. Click
here to view a labeled image of this parasite, or
here to view a labeled line drawing.
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