As we approach lambing time we are confronted with the occasional or sometimes the true abortion storms.
What do we do?
How do we approach the problem?
Diagnosis
We must first diagnose the problem before we can have a chance at stopping the abortions.
The success of making a diagnosis is proportional to the quality of the sample delivered to the laboratory. It is important that both the
placenta and the fetus be presented is as fresh a state a possible. Diagnosing abortions is a numbers game.
The more samples submitted the better the chance of a diagnosis.
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When abortion occurs:
1. Place the fetus and membranes in a plastic bag and get it to the laboratory immediately.
2. If you are not submitting the fetus to the laboratory bury or burn the fetus, membranes and any soiled bedding or feed. Make certain that other ewes do not have access to contaminated bedding, feed or water.
3. Abortion storms (numerous abortions near lambing time) - Although many organisms can cause abortion, there are three that cause the majority of the problems:
Campylobacter, Chlamydia and Toxoplasma
What to do before the diagnosis comes back from the laboratory
Medicate the entire flock with LA 200 or Tylan 200.
Consult your local Veterinarian for specific details.
Preventing Abortions
SANITATION: Do not feed on the ground. Keep feed and water free from contamination of placental membranes and fluids. Remember, no bacteria or virus has developed a resistance to good sanitation.
VACCINATIONS: vaccines are available for campylobacter and chlamydia. My recommendation is to use these separately as they have different incubation periods. Keep in mind that all vaccinations take the initial dose followed by a booster in about 10-14 days then an annual booster. Chlamydia needs to be given prior to breeding.
Campylobacter boosters are probably more effective given the last 1/3 of gestation. To give the lamb protection, through the colostrum, from Clostridial infections the clostridial vaccines can be given at the same time with the Campylobacter.
If E.coli and roto/corona are annual scours problems, the ewes can be vaccinated at this time with these products.
Consult your local veterinarian on the availability of products and their use in you flock.
Toxoplasma Abortions
Toxoplasmosis is caused by a protozoan parasite that infects most species of warm-blooded animals, including birds and man,throughout the world.
The causative agent - Toxoplasma gondii. Life cycle - The parasite has a rather complicated life cycle which includes rodents and cats and when placed in the sheep's environment will cause abortions. Members of the cat family are the only definitive host of the Toxoplasma organism and, therefore , serve as the main reservoir. Cats become infected early in life and develop an immunity after shedding the organism for about 20 days. This fact is important in the control of the disease in sheep.
The disease is transmitted to sheep via contaminated feed or water. Barn cats, using the feed bin or bunk for a liter box, is a common source of contamination. In sheep, the abortions happen in late pregnancy from the disruption of blood flow through the placenta to the fetus. This causes necrosis of the placental attachment (cotyledons)resulting in death of the fetus with resorption, mummification, maceration of the aborted fetus or stillborn and weak lambs. The ewes do not appear ill and recover form the abortion quickly. The ewe develops a lifetime immunity.
Diagnosis
A history of abortions. The cotyledons are red to tan-colored with typical white pinpoint areas of calcification. Take both fetus and placenta to the diagnostic laboratory.
Treatment
There is no treatment in sheep.
Prevention
Since cats are the primary reservoir of the Toxoplasma organism, prevention is directed at controlling the cats. Infected kittens develop an immunity and cease shedding organisms after about 20 days.
CAUTIONS
This disease is transmissible to humans. Pregnant women are at a very high risk as the organism can pass through the placenta to the fetus and may cause birth defects or mental retardation. Cats are the main source of the organism but abortions from sheep also are a source of human infection. Pregnant women should be especially cautious of exposure from sheep at lambing time or contact with cats. The organism can live in the environment for up one year, therefore, cats can contaminate the garden, the flower bed or other places. Sanitation is the main prevention.
Reference reading materials
- Youngquists "Current Therapy in Large Animal Theriogenology" Saunders Publishing Co. 1997 pp..624-625
- The Merck Veterinary Manual Eight Edition 1998 pp.488-489
Zoonosis Update from the Journal of the American Veterinary Medical Association, Second Edition 1995 pp.144-149
