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United Suffolk Sheep Association |
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How many abortions are normal? Marie S. Bulgin, DVM Coordinator of the Idaho Veterinary Teaching Program and the Caine Veterinary Teaching Center This time of year everyone’s attention turns to lambing, a pretty exciting time of year. This is when you find out if that great looking, very expensive, super ram you bought at the Big Show of the Year is worth his salt, pellets and hay, never mind the purchase price. So, when the first couple of ewes abort and the next couple of lambs are stillborn, and one of the third set is weak and dies in spite of your best efforts, it is a depressing and frustrating experience. All of the above are symptoms of infectious abortion and by the loss of the second set of lambs the experience should motivate you into action. Sheep producers take a lot of abuse, although things have to get much worse than the above before they realize that God is not punishing them for forgetting their spouse’s birthday, or yelling at the kids, or getting a little tipsy at the New Year’s party. We are talking disease here, and although you might also want to blame it on a random act of Nature, it’s not! Abortion in sheep can be caused by 5 or 6 different problems, but most of it is caused by one of three agents: Campylobacter (Vibrio), Chlamydia (EAE) or Toxoplasmosis. And the good news is, all three can be prevented or controlled. Toxoplasmosis is the easiest to prevent since it is spread by kitten poop. Generally, adult cats are immune to the disease and are free of it, but half grown kittens can shed a lot of the parasite. Since one of the favorite bathroom facilities for half grown barn kittens is the grain bin or feed troughs, it is not difficult to imagine how the ewes get it. Besides keeping kittens out of the barn and feeders during the late pregnancy period of the ewes, Rumensin of monensin can be fed during the last 6 weeks of pregnancy to prevent the Toxo cysts from hatching and infecting the tissues, including the fetus and placenta of the ewe. An added advantage is the drug will also control Coccidia at the same time, which isn’t a bad idea either. Chlamydia and Campylobacter are usually an added but hidden addition to what you buy when buying new replacements. Although Campylobacter can be carried by dogs, birds and even people, the Chlamydia organisms really prefer sheep. Just some background on Chlamydia; it has a long incubation time, ie, the time from ingestion of the organism to the time it causes abortion is 120-150 days. Generally, the ewes become infected during the preceding lambing period when exposed to ewes that are aborting. Depending when in gestation they are when exposed, they will lamb naturally and abort the following year. If exposed early enough in their gestation, ie 30-60 days prior to lambing, they may have weak lambs or stillbirths, or the lambs may be normal and just not grow well. This sort of nightmare usually happens the first time a flock is exposed. After that there is a certain degree of herd immunity, probably colostral, that seems to help protect live lambs. However, female lambs will still harbor the organism and abort the following year. So, if you have first time lambers aborting, you probably purchased the disease with the replacements. Otherwise, the greatest incidence would be in your second time lambers. Fortunately, Chlamydia is relatively easy to prevent, because it is sensitive to tetracycline. Once Chlamydia is diagnosed in a flock, it can be controlled by either feeding it or putting it in the drinking water for the last 6 weeks before lambing begins. If abortions have been diagnosed in the flock, the dose should probably be 500 mg/head/day, while 250 mg/head/day will usually control the disease if abortions have not yet started. Campylobacter is the toughest bug of the bunch because there are more than one species and subspecies that cause sheep abortion, so vaccination is not always effective. About 1/3 of them are resistant to tetracycline, so sensitivities have to be done in order to know what to use for a preventative and when you do find out, the antibiotic is often expensive and not cleared for use in sheep. Vaccination is often very good for prevention unless you have a different strain in your sheep than is in the vaccine which happens time to time. Then it is tremendously important to attempt to prevent spread. Cleaning the area of the abortion, burning a bale of straw or poor quality hay over the area, digging up the ground if it is in the barn and throwing the soil some place other than the sheep pens, pouring disinfectant over the area – any and all of the above will help. Isolate the ewe as her vaginal drippings will be heavily infected for one to three weeks. Then, she most likely will be immune to abortion by Campylobacter, but she can still shed it in her feces. Getting the placenta cultured as soon as possible is muy importante!! The sooner the bug is cultured, the sooner a sensitivity can be done and you find out what the big hammer is. Then chances are you will need your veterinarian to help you figure out how to give it, how much to give and where to get it. So, of course the best way to prevent the two big “Cs” is hopefully not to purchase it. Keep the cats and dogs away from the barn, feed troughs and grain storage during gestation. Ask a few questions of the owner of the flock you wish to get your replacements from. Rams can carry disease too- one good reason for not letting the old boy run with the ewes all year. Vaccinate annually for Campylobacter. Vaccinate new replacements for Campylobacter, just in case the old owner didn’t do a good job, or confused enterotoxemia for Campylobacter when he insisted they were vaccinated. If you live in the Midwest and eastern U.S., feeding of Rumensin will control Toxoplasmosis, which is much more prevalent in those parts of the country. If you have purchased white-face Rambouillet type ewes from the Western states renown for carrying Chlamydia, start tetracycline feeding 45-60 days before lambing.
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