Abortion is when a female loses her offspring during pregnancy or when giving birth to weak or deformed babies.Abortions can be caused by infectious or non-infectious agents. Non-infectious abortions can be caused by trauma such as fighting or rough handling, but are not common. The main infectious agents that cause abortion in sheep and goats are:
Vibriosis(Campylobacter): these infections result in late pregnancy abortions or still births. They are seen much more commonly as a cause of abortion in ewes than indoes.
- Chlamydia (Enzootic Abortion of Ewes or EAE): These infections cause abortions during the last 2 to 3 weeks of gestation resulting in stillbirths and weak offspring. Ewes and does infected by this bacterium rarely abort more than once but can continue to shed the bacteria from their reproductive tract infecting other herd members. If the abortions occur in ewe lambs or young ewes it is likely due to this agent
- Toxoplasmosis: This is a protozoan parasite for cats and rodents. They spread the agent into the hay or feed which is eaten by the stock through the faeces. If ewes or does contract toxoplasmosis early in gestation, they usually reabsorb the fetus. When infected later in gestation, abortions are common.
- Leptospirosis: it is caused by the bacteria Leptospira interrogans which cause abortion in goats. It is transmitted when animals come into contact with standing water (lake or pond with the bacteria). Symptoms include anemia and icterus (yellowish pigment of the skin and eyes).It can be a symptom of anemia or liver disease. Diagnosis can be made by testing the dam’s urine the aborted fetus or the placenta.
- Q fever: is caused by the bacteria Coxiella burnetii which is found in milk, urine, feces, placental tissue and amniotic fluid as well as spread through the air. Pasteurization is effective in killing the bacteria in milk. Symptoms in ruminants include anorexia, abortion and lesions. Diagnosis of the disease is usually done from an infected placenta which will be covered with a gray-brown secretion. The disease can be spread to humans especially farmers, veterinarians and researchers who assist in the birthing process who often exhibit flu-like clinical signs.
Care should be taken when handling aborted fetuses or placentas, as all the pathogens that cause abortion in sheep and goats can be transmitted to humans.
- Campylobacter and Chlamydia bacteria are often spread to a noninfectedherd or flock when a purchased animal is introduced from another farm.
- Campylobacter and Chlamydia are,transmitted by ingestion of materials in contact with infected feces or fetal and placental fluids.
Treatment and control
- If the abortions are due to an infection by Campylobacter bacteria, infected animals are often responsive to either tetracycline or sulfa drugs to prevent further abortions. There is also vaccination to prevent the Campylobacter infections.
- Abortions due to Chlamydia bacteria can be stemmed by treating ewes with tetracycline given in the feed or by injections. A vaccine can also be used to prevent the infections.
- The only treatment for toxoplasmosis is prevention.
- It is important for farmers to cover stored feed and discourage stray cats from hanging around housing for gestating ewes or does.
- Feeding a coccidiostat such as Monensin or Decoquinate mixed into feed can also be effective in preventing abortion due to toxoplasmosis.
- Outbreaks of Q fever can be managed by administering tetracycline
- Separating pregnant animals inside from the rest of the herd
- Burning or burying reproductive waste.
- Any new additions to the flock or herd should be quarantined or if they are pregnant ewes or does penned separately until they give birth.
- Feeding high doses of tetracycline prior to lambing or kidding has been effective in reducing Chlamydia andCampylobacter abortions.
- Ewes or does should not be fed on the ground
- Vaccination for Campylobacter and Chlamydia is important for flock or herd health and it is advisable to practice such.
It is important to include the part of the placenta where lesions are present as this is critical to identification. Producers can work with veterinarians when packaging and shipping the fetus and placenta. To prevent the spread of infectious agents while waiting for results from the diagnostic lab, aborting ewes or does must be isolated from the rest of the herd, and aborted fetuses or placentas should be removed from the pen.