A severely parasitized lamb that died
most common health problem of domestic sheep, especially young
lambs, is internal parasites (worms). There are many different
types of worms that can cause problems to sheep, but stomach worms
are the most common. Stomach worms cause many symptoms in sheep
and lambs and can result in death if the symptoms go undetected.
The worm that causes the most losses in sheep flocks is the barber
Barbor Pole Worm
contortis, better known as the barber pole or wire worm,
is a blood sucking parasite that cause blood and protein loss
(anemia) in the sheep. It pierces the lining of the sheep's
abomasum (or true stomach). It causes anemia as
evidenced by pale mucous membranes, shown in the picture below
(left). It can also result in a condition called "bottle
jaw," (below, right) which is an accumulation of
fluid under the sheep's jaw.
Pale mucous membranes
become infected with worms when they graze. After they consume
the infective larvae on the pasture, the larvae
develop into adult worms and lay eggs inside of the sheep's digestive
tract. The eggs are deposited on the pasture when the sheep poops.
Once on pasture, the eggs develop into infective larvae that are
consumed by the sheep and and the cycle starts all over again
unless the sheep are treated with an effective drug, then moved
to a place where there aren't any worm eggs to be re-ingested.
The environmental conditions which are most conducive to the parasite
life cycle are warm and moist.
are more susceptible to worms than cattle because they graze closer
to the soil surface. As animals get older, they begin to develop
immunity to parasites, but it takes longer in lambs
than calves. When a ewe lambs, her immunity to parasites is temporary
Drenching is when you give
worming medicine to the sheep.
the past, worms were effectively controlled with anthelmintics,
drugs that kill parasites. But nowadays, the worms have become
resistant to most of the drugs, making parasite control more difficult.
Scientists are working hard to find new ways to control parasites
in sheep and goats.
in South Africa developed a system called FAMACHA© (named
for its originator Dr. Faffa Malan) whereby you compare the
color of the sheep's lower eyelid to a score card to determine
its "eye score" and need for deworming.
This way you only treat the animals with clinical signs of parasitism
instead of treating all of the animals in the flock. This helps
to slow down the rate by which the worms become resistant to
red eye lid indicates a healthy sheep.
stomach worm egg.
A microscopic fecal test can also be used to pinpoint
the need for deworming. However, unlike fecal tests for dogs and
cats, the mere presence of worm eggs does not mean a sheep needs
treated for worms. It is normal for sheep to have parasites. Rather
it is the number of parasite eggs that are found in a gram of feces.
The number of eggs gives an indication of how much that sheep is
contaminating the pasture with eggs that have the potential to develop
into infective larvae and infect other sheep and lambs. The purpose
of deworming in this case would be to reduce the source of contamination.
Go BACK to Zoonotic Diseases.
. . . New Words . . .
- deficiency in red blood cells.
jaw - an accumulation of fluid under the jaw.
- immature stage for worms.
- natural or acquired resistance provided by the immune system
to a specific disease.
- a substance with the property to destroy or expel intestinal
Deworm - give medicine to kill worms.
- force to drink.
- relating to feces or "poop."