A. Anderson, DVM
Abortion in ewes has many
causes. Some are infectious like enzootic abortion of ewes (EAE)/chlamydiosis
(Chlamydia psittaci), vibriosis/campylobacteriosis (Campylobactre
fetus), brucellosis (Brucella spp.), toxoplasmosis
(Toxoplasma gondii), listeriosis (Listeria
monocytogenes), and salmonellosis (Salmonella spp.).
Others are toxic like hellebores (Veratrum spp.), kale
(Brassica spp.), locoweed (Oxytropis spp.),
poison/milk vetch (Astragalus spp.), broomweed (Gutierrezia
microcephala), coumarins (rat poison, moldy grass or sweet
clover), and mycotoxins (usually those that mimic the hormone
estrogen). Still other diseases and toxic plants can cause
abortions under certain conditions. Malnutrition, abrupt
nutritional changes, and heat stress have been implicated and
several more causes are currently under investigation.
In most cases of abortion,
the actual cause is long gone by the time the abortion
actually occurs, making a positive diagnosis difficult. A
decomposed fetus or contaminated area further complicates the
diagnostic efforts. Some toxins require extensive testing at
special laboratories. In reality, due to the variety of causes
(etiologies) and diagnostic hurdles, as many as 40-50% of all
ovine abortions may go undiagnosed. This often explains why a
plan that might work for one flock has no effect in a second
While the odds may not
look promising, establishing at least a presumptive diagnosis
is necessary to take corrective action or develop a
preventative plan. Isolate the aborting ewe and aborted fetus
from the rest of the flock. These materials may be infectious
and can be transmitted to the other ewes. Call your
veterinarian as soon as possible. They can advise you on how
to handle the material before they arrive to collect samples.
After the examination, dispose of the fetus and aborted
tissues properly and disinfect the area very well. Care must
be taken while handling the material because some of the
infectious agents are also contagious to man.
Two of the most common
causes of ovine abortion are EAE (enzootic abortion of ewes)
and vibriosis/campylobacteriosis. If these diseases are
confirmed or suspected, a preventative plan should include
vaccination of the flock and all future new arrivals to the
At Colorado Serum Company,
we carry a full line of sheep vaccines, which include two
specifically developed to prevent ovine abortion.
For the prevention of enzootic
abortion of ewes (EAE) caused by Chlamydia psittaci.
Vaccinate ewes sixty days prior to
breeding with a booster dose thirty days later.
Revaccinate yearly prior to breeding.
BACTERIN, Ovine origin
For the prevention of vibrionic
abortion of ewes (vibriosis/campylobacteriosis) caused by Campylobactre
fetus subspecies jejuni (type I) and subspecies
intestinalis (type V).
Vaccinate ewes thirty days prior to
breeding with a booster dose sixty to ninety days later.
Revaccinate yearly around breeding time.
As always, read and follow
For help with your flock
health program, feel free to give our veterinary staff a call.