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Causes of Infectious Abortions
in Goats
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Maria Lenira Leite-Browning, DVM
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Extension Animal Scientist
Alabama A&M University |
Goat herds generally have a 2
to 5 percent abortion rate. Any percentage above this
is a serious problem because abortions can lead to
economic losses. Indeed, infectious abortion in a
doe herd can be a public health concern because infectious
agents that cause abortions in goats can also infect
and cause diseases in humans. Infectious abortions
should be taken seriously by the producer and herd
manager. |
The most common microorganisms that cause abortions
in goats are:
Chlamydiosis (Chlamydia psittaci)
Query or Queensland (Q) fever (Coxiella burnetii)
Listeriosis (Listeria monocytogenes)
Leptospirosis (Leptospira spp)
Toxoplasmosis (Toxoplasma gondii)
Brucellosis (Brucella melitensis) |
|
Chlamydiosis (Chlamydia, Enzootic Abortion) |
Chlamydiosis, commonly known
as chlamydia, is the most frequent cause of abortion
in goats in North America. It is associated with pneumonia,
pink eye, inflammation of epididymis (a part of the
buck's reproductive system), and inflammation of the
joints. It can be transmitted to does through the
direct contact of feces from infected pigeons and
sparrows. Chlamydia can be also transmitted to goats
by ticks or other bloodsucking insects. |
Chlamydia multiplies in the blood
and is located in the reproductive organs of the doe.
In pregnant does, this microorganism can be found
in the fetus and placenta, leading to an inflammation
of the placenta that prevents normal transfer of nutrients
from the doe to the fetus. It can also lead to miscarriage
or abortion. Abortions can occur any time between
days 100 and 130 of gestation. Does may show no symptoms
other than a bloody vaginal discharge two to three
days prior to aborting. During the first three weeks
after abortion has occurred, the doe will have uterine
discharge containing chlamydia. If chlamydia is not
diagnosed and treated, the infection will persist
and the infected doe may abort again during the next
pregnancy. |
| Diagnosis |
A diagnosis of chlamydiosis is
based on the history of the herd, clinical signs,
and characteristics of the placenta. When chlamydiosis
is suspected, aborted fetuses and fresh placenta should
be packed in ice, marked with correct identification
of the doe, and sent to a lab for positive diagnosis.
Up to three days after abortion, a vaginal swab should
be taken by a veterinarian and sent to a diagnostic
laboratory for isolation of the microorganism. Serum
samples from the aborting doe can also be used for
immunological tests, such as the enzyme-linked immunosorbent
assay (ELISA) or the indirect inclusion fluorescence
antibody (IIFA) tests for diagnosis. |
The presence of chlamydial antigens
in ground placenta or vaginal swabs collected just
after abortion may be detected by ELISA with diagnostic
kits developed for human C. trachomatis infections.
In human medicine, polymerase chain reaction (PCR)
or its variation, ligase chain reaction (LCR), are
considered to be the most sensitive diagnostic methods
available for diagnosis of chlamydia. But this is
expensive. |
| Treatment and Prevention |
Infected does should be treated
with tetracycline, oxytetracycline, and chlortetracycline.
The injection of 20 mg/kg of oxytetracycline given
by intramuscular route at 105 and 120 days of pregnancy
can prevent abortion but cannot prevent chlamydial
shedding at kidding. Tetracyclines affect the replication
of chlamydia and can be effective in preventing abortions.
Chlamydia psittaci are susceptible to chlortetracycline.
In an infected herd, abortion can be prevented by
administrating 80 mg/head/day during pregnancy. In
an outbreak, 250 mg/head/day for 3 weeks has been
recommended and appears to be effective. |
Listeria |
Listeriosis is caused by the
bacteria Listeria mono-cytogenes (Lm), which can be
found in soil, contaminated water, and spoiled, concentrated
hay or silage. It can live in soil and fecal contents
for a long time. After infecting, the bacteria multiply
and spread throughout the animal's body, causing fever
and decreased or loss of appetite. Lactating does
show reduced milk production. Infected does show neurological
disturbance due to encephalitis (inflammation of the
brain). Abortion can occur at early stages of pregnancy
and infected does can produce stillborn or weak kids. |
The prevalence of Lm on goat
farms is seasonal. Management practices are associated
with listeriosis and fecal shedding of Lm. Awareness
of risk factors may be used to develop control measures
to reduce disease and introduction of Lm into the
human food chain. Listeria is a public health concern
and may affect humans. It primarily affects people
whose immune systems are inefficient, including newborns
and the very old. In pregnant women, listeria may
cause infant deaths, meningitis, or spontaneous abortions. |
| Diagnosis |
Brain tissue, aborted placenta,
and fetus specimens should be isolated and identified
for the presence of Lm. Tissue must be identified,
refrigerated (4 degrees C), and sent to a reference
laboratory for isolation of Lm. This microorganism
has been isolated from the spinal fluid, nasal discharge,
urine, feces, and milk of infected does. Serology
is not used routinely for diagnosis because many healthy
animals have high Listeria titers. Immunofluorescence
is effective for quickly identifying Lm in smears
from dead animals, tissue from aborted fetuses, milk,
meat, and other sources. |
| Treatment and Prevention |
Stop using contaminated food.
Generally, procaine penicillin should be administered
every 6 hours for 3 to 5 days then daily for an additional
7 days. Administration of 500 mg of chlortetracycline
a day per goat is also recommended. Chloramphenicol,
oxytetracyclin, and ampicillin have shown success
in treating listeriosis. Intravenous sodium chloride,
glucose solutions, and sodium bicarbonate are also
useful. |
Leptospira |
Leptospirosis can cause abortion,
stillbirths, or the birth of premature or weak, infected
kids. The most common serovars, a subdivision of a
species different from other strains, causing abortions
in goats are Leptospira interrogans, grippotyphosa,
and pomona. Goats are susceptible to these strains,
with abortion occurring after infection at the time
when the microorganisms start to multiply in the doe's
blood. Some have shown anemia and jaundice (yellowing
of the tissues, usually resulting from abnormal liver
function) and hemoglobinemia (part of red blood cells
that carries oxygen). However, an infected doe may
not have fever or jaundice. |
| Diagnosis |
Diagnosis is based on the microscopic
agglutination test (MAT) and the ELISA. Isolation
and identification of Leptospira spp in the doe's
urine, placenta, or fetal kidney tissues is the most
accurate method of diagnosis. |
| Treatment and Prevention |
Tetracycline and oxytetracycline
may be successful if given early in acute cases. Erythromycin,
enrofloxacin, and tiamulin are also effective in acute
cases. Oxytetracycline, amoxicillin, penicillin G,
Tylosin, and doxycycline can be used with success.
Treatment has a limited effect on the course of disease
once uremia (presence of excessive amounts of urea
and other nitrogenous waste products in the blood)
has developed. |
When abortion caused by Leptospira
is diagnosed in a goat herd, further abortions can
be prevented by promptly immunizing the entire herd
and simultaneously treating all animals with antibiotics.
Only sick does should be treated with antibiotics.
In a zone with a high incidence of leptospirosis,
annual immunization of the herd is recommended. Management
methods to reduce transmission include controlling
rodents, keeping the herd from potentially contaminated
streams and ponds, separating goats from wildlife,
selecting replacement stock from herds that are seronegative
for leptospirosis, and immunizing replacement stock. |
Toxoplasmosis |
Toxoplasmosis is caused by the
Toxoplasma gondii microorganism. It is another common
cause of infectious abortion in goats, other animals,
and humans. Cats can be carriers of T. gondii. Cats
often defecate and bury their feces in the hay and
food storage areas of barns. Does can become infected
by ingesting food or water contaminated by feces. |
T. gondii enters the bloodstream
of the doe and spreads to other tissues. In pregnant
does, T. gondii can invade and multiply in the placenta
and pass to the fetus, causing fetal death, fetal
mummification (where the doe reabsorbs the fetal fluid),
stillbirth, or the birth of weak kids. In some cases,
the pregnancy can progress normally and the doe can
give birth to a normal kid. Abortions from this microorganism
occur mainly in the last trimester of pregnancy and
may occur in does of all ages and in successive pregnancies. |
Humans can be infected by T.
gondii by ingesting meat and milk from animals with
toxoplasmosis. Toxoplasmosis can be a public health
concern because children who are allergic to cow milk
often consume non-boiled goat milk. |
| Diagnosis |
Diagnosis is based on clinical
signs and by isolation of T. gondii from placental
and fetal tissue. Samples for diagnosis should be
shipped on ice but not frozen. If the placenta is
not available or is decomposed, diagnosis can be done
by testing for the presence of the antibody against
T. gondii in fetal fluid or in doe serum. T. gondii
can be isolated from the vaginal mucosa, saliva, nasal
secretion, and urine from experimentally infected
goats and in the milk of naturally infected goats.
Toxoplasma infection in both humans and animals can
be diagnosed using various serological tests, such
as indirect haemagglutination, indirect immunofluorescence
(IFAT), or ELISA. |
Serological analysis using IFAT
and ELISA has been widely employed to detect herds
contaminated by Toxoplasma, including swine and sheep. |
PCR (polynucleotide chain reaction)
can be effective in the diagnosis of toxoplasmosis.
DNA can be extracted from the lung, muscle, and mesenteric
lymph node of the doe and lung tissues of the aborted
fetus. A direct PCR assay is effective for the diagnosis. |
| Treatment and Prevention |
Feeding decoquinate (2 mg/kg
bw/day) or monensin (15-30 mg/head/day) throughout
pregnancy may reduce the abortion rate in a herd with
a history of toxoplasmosis. Sulfonamides are used
to treat toxoplasmosis in goats. Clindamycin (12.5
mg/kg, IM, BID for 3 weeks) is also recommended. There
is no vaccine available in the United States. Control
of toxoplasmosis is based on management practices;
pregnant females should not be exposed to infected
cat feces. Note: Cats should be tested for the T.
gondii microorganism routinely. |
Q Fever |
Query or Queensland fever can
cause goats to abort. Q fever is caused by the microorganism
Coxiella burnetii and is a disease that affects many
animals and humans. Ruminants can contract Q fever
when grazing contaminated pastures and from tick bites.
In a co-grazing system, infected cows and sheep may
be a source of infection for goats. Other animal species
and humans can be infected by inhaling contaminated
dust. In infected goats, the microorganism can be
found in the placenta, uterine fluid, and milk. Infected
animals show no symptoms of the disease until aborting
or having stillborn kids in late pregnancy. Does do
not generally show any symptoms of the disease until
1 to 2 days before abortion, when they experience
a lack of appetite and depression. |
| Diagnosis |
Diagnosis is based on isolation
of Coxiella burnetii in the placenta. Be aware of
possible infection by Coxiella b. Wear gloves when
helping the doe at the time of kidding or when handling
aborted fetus. Placenta and aborted fetuses should
be burned or buried. Detection by PCR and immunofluorescence
tests of Coxiella b. in parturition products and vaginal
secretions at abortion are preferred over serological
tests. |
| Treatment and Prevention |
There is no vaccine to prevent
Q fever in goats. Feeding 200 mg/head/day of chlortetracycline
in the feed for 19 days or using 20 mg/kg of long-acting
oxytetracycline every 3 to 14 days should control
the infection. |
Brucella |
Brucellosis, also known as undulant
fever or Malta fever in humans, is caused by Brucella
melitensis. Although brucellosis in goats is considered
non-existent in the United States, there was a case
reported in a South Texas goat herd in October 1999. |
Goats can be infected by Brucella
melitensis (a specific strain that causes disease
in goats) or Brucella abortus (a specific strain that
causes disease in cattle) by ingesting Brucella from
contaminated feed, pasture, or water. Brucella then
spreads through the blood and becomes localized in
the lymph nodes, udder, uterus, testes, and spleen.
Infected does show signs of fever, depression, weight
loss and diarrhea that can also be accompanied by
lameness or mastitis, inflammation of the mammary
gland. Infected bucks may develop orchitis, an inflammation
of the testicles. |
In pregnant does, Brucella can
be localized in the placenta leading to the development
of placentitis (inflammation of the placenta) with
subsequent abortion, commonly around the last month
of pregnancy. |
Brucella can be found in milk,
urine, feces, placenta, and vaginal secretions that
accompany natural birth or abortion. In the case of
normal full-term births, kids from infected does are
often infected and capable of spreading the disease. |
| Diagnosis |
Diagnosis is achieved by isolating
the microorganisms from the aborted fetus, placenta,
or vaginal discharge in laboratory tests. Positive
animals are identified by serologic examination. The
indirect enzyme-linked immunosorbent assay (iELISA)
is sensitive and specific, and shows potential for
use as a bulk milk test for detecting B. melitensis
antibodies in goat milk. |
| Treatment and Prevention |
There is no treatment for brucellosis
in goats. It is mandatory to eliminate infected animals.
Vaccination of goats is not permitted in the United
States. |
Note:
Ceftiofur and Neomycin
are the only two antibiotics approved to use in
goats. The other antibiotics mentioned in this
article are considered extra-label. Consult your
veterinarian for extra-label antibiotic use, side
effects, and withdrawn period.
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What to do when abortion occurs: |
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| References |
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