Abortion and Perinatal Loss in Sheep and Goats

Lecturer: Dr. Donal O'Toole

Abortion and perinatal loss in sheep and goats is both simpler and more complex than the conditions in cattle.  Simpler, as the number of infectious agents involved is fewer.  Some (but not all) can be vaccinated for.  More complex, since at least three of the important agents are transmissible to people - they are zoonotic.  If you have to deal with an abortion storm in sheep or goats, assume that it may be one of the zoonotic agents.  Protect yourself (gloves and calving gown; soap; disinfectant; bury or burn fetal membranes and fetuses).  Several of the agents cause illness, including abortion, in pregnant women.  Pregnant women and people with immuocompromising diseases should avoid involvement with lambing ewes or kidding goats.  They should not handle contaminated clothing from those who worked with lambing ewes and newborn lambs.

Abortion rates above 5% should trigger a suspicion that something infectious is involved.  Below I list some of the important ones for our area.  Other agents can be involved elsewhere in the USA.  These include Cache Valley and bluetongue viruses, sarcocystosis, and iodine deficiency (goiter).

1.  "Vibrio" in sheep (cause: bacterial; Campylobacter fetus subspecies intestinalis and jejuni)

This disease is correctly called campylobacteriosis.  The old name for the organism, Vibrio, continues to be widely used. This is the most important single diagnosed cause of abortion in Wyoming.  Abortion rates may be in the 10 - 20% percent range.  They can reach 80% in completely naive flocks, particularly when the tally includes perinatal loss due to lambs born alive but then die.  Infected ewes generally recover following abortion and are solidly immune to reinfection. Some ewes remain persistently infected and continue to shed bacteria in feces.  This is one reason why pregnant ewes should not be fed on the ground (two other abortifacient agents, Salmonellla and Chlamydophila, are also shed in feces and can be acquired from the ground). Some aborting ewes die of complications, such as an infected uterus (metritis), fetal retention, or peritonitis. Stillbirths and weak lambs are common. Vibrio abortion in sheep is not venereal (unlike the related Campylobacter sp. disease in cattle). Ewes are infected by ingestion of the organism.  Since the agent can be found in wildlife, including birds, some producers are preoccupied with this as a potential source.  Failure to vaccinate, and introduction of one or more infected ewes, is the most common scenario prior to an abortion storm.  We only see the disease in flocks where a vibrio vaccine is not used.

Vaccine: YES

Antibiotics: YES (make sure the laboratory isolate is sensitive to what you use).

2.  Chlamydial abortion in sheep and goats (cause: bacterial; Chlamydophila abortus)

Enzootic abortion of ewes (EAE) is characterized by abortions, stillbirths and weak lambs. When EAE first appears in a flock, abortion rates run from twenty-five (25%) to sixty (60%) percent. Once the disease becomes established, losses in subsequent years drop to 1 - 5%. Clinical evidence and history of a low incidence of EAE in the Midwest suggest that the disease is endemic there. In the West, isolated range flocks become highly susceptible when the disease is introduced. Likewise, when ewes from clean Western flocks are introduced to endemic areas in the Midwest, high abortion rates may occur. Ewe lambs are the most susceptible age group when exposed on endemic farms. The organism can also cause pneumonia in young lambs. Initially, it was thought that the disease was spread only through contact with infected fetuses, placentas or vaginal discharges. However, clinical evidence indicates that the disease may be spread by infected sheep constantly shedding agent in feces or from lungs - so it replicates in cells lining the gut, and also cells in the respiratory tract.  The organism enters a non-pregnant ewe and lays dormant until the animal conceives. The organism does not initiate an immune response during the dormant stage. During the infective stage, the ewe develops an immune response that clears the organism from her system.  The Chlamydophila agent that causes abortion is distinct from a related agent that causes conjunctivitis/polyarthritis in lambs.  The vaccine for the conjunctivitis agent does NOT protect against the abortion agent.

VACCINE: YES

ANTIBIOTICS: YES

Extension piece by Dr. Susan Rodger at Moredun Research Institute on EAE

3.  Border disease in sheep (cause: viral; pestivirus closely related to BVDV)

Border disease was first reported in 1959 along the English/Welsh border, hence the name. You may sometimes hear it called ‘hairy-shaker’ or ‘fuzzy-lamb’ disease.  The disease it causes is similar to that of BVDV in cattle.  Indeed, some strains of BVDV cause a border disease-like syndrome.  It causes minimal effects in the dam.  If it infects young post-natal lambs, the outcome can be serious.   As with BVD, the clinical outcome depend on the time at which fetal lambs are infected in gestation.  Infection before mid-gestation (~80 days) results in abortion or the birth of persistently infected lambs ("hairy shakers").  These lambs are hairy because the virus infects and damages cells of the primary hair follicles; they shake because of damage to myelin-forming cells in the CNS.  Myelin's normal function is to form an insulation-like wrapping around nerve fibers in the central nervous system; when the myelin is reduced, nerves can still talk together, but less well.  The clinical effect is similar to multiple sclerosis in people.   After ~80 days, when the fetus can mount an immunological response, the outcome varies from abortion, stillbirth, weak lamb, to nothing at all.  This is important since lambs aborted before 80 days will still be infected; those born after ~ 80 days have no detectable virus.  This makes confirmation of border disease abortions a problem at the laboratory end.  As in BVD, some lambs infected early in gestation survive and remain infected for life.  They are a constant source of infection.  Sheep-to-sheep contact is the principal way in which BDV is spread.  The most potent sources of virus are PI sheep. Flocks with no previous exposure to the virus are particularly vulnerable.  Purchase of PI replacement ewes is the commonest way of introducing infection. These animals constantly shed low levels of virus from the skin and excrete it in feces and urine. The highest concentration of virus, however, is in nasal secretions and saliva. The spread of virus in a susceptible flock exposed to one or more persistent excretor animals will depend on contact between sheep. Housing during early pregnancy has been shown to result in explosive outbreaks of border disease. To avoid the risk of infection with BVDV, pregnant sheep should not be mixed with cattle.

VACCINE: NO - there is such variability among pestiviruses that BVD vaccines are unlikely to protect from BDV

ANTIBIOTICS: NO

4.  Toxoplasmosis in sheep (cause: protozoal agent belonging to the coccidia family;  Toxoplasma gondii)

Toxoplasmosis is a common causes of abortion in Europe (27% of all diagnosed causes of abortion in sheep in UK, 1995 - 2003) and the Midwest.  We have rarely seen it in Wyoming.  I assume the main reason is that there is less opportunity for cats, which shed the agent in their feces, to have contact with range flocks. Toxoplasma abortion in ewes follows ingestion of feed or water which has been contaminated with oocyst-laden cat feces. The infection is maintained in cats, who often acquire it from infected rodents.  Toxoplasmosis generally does not cause clinical symptoms or detrimental effects in open, healthy ewes.  The result of toxoplasmosis in pregnant ewes varies with the age of the fetuses when the ewe is infected. Infection in the first two months of gestation results in embryonic death and resorption.  Infection in mid gestation results in abortion and infection. Infection in the late gestation results in abortions, stillbirths, mummies or weak lambs. Flock abortion losses attributable to T. gondii can involve from 5% to 50% of the ewe flock.  Typical losses are 15 - 20% of the lamp crop.   T. gondii can infect people and cause a mild flu-like illness - a colleague of mine developed this when I was in practice in Ireland.  In pregnant women and immunocompromised individuals infection can be more serious and on rare occasions be fatal

Ewes that become infected develop solid immunity.  There has been some suggestion that infected ewes abort repeatedly.  The institute that has done much of the pioneering work on this disease (the Moredun Research Institute in Scotland) has found little evidence to support this.  Ewes that abort should be retained in the flock since they are solidly immune.

VACCINE: NO - not in US.  There is a vaccine made by Intervet called Toxovax^TM.  It is licensed for use in New Zealand and several European countries.  This live vaccine should not be used in pregnant ewes, and should not be administered by pregnant women or immunocompromised people.  It is unlikely to be licensed in the US anytime soon.

ANTIBIOTICS: NO

IONOPHORES: YES for control (decoquinate. dose is x4 FDA recommended dose)

5.  Q fever in goats and sheep (bacterial; Coxiella burnetii)

Q fever is caused by the rickettsial agent Coxiella burnetii.  It is more common as a cause of abortion in goats than sheep.  We have seen it in Wyoming, mostly in goats.  Human cases of Q fever are associated with exposure to abortions in sheep and goats, drinking unpasteurized goat milk and eating soft cheeses, and contact with clinically healthy infected sheep and goats. Most human infections with C. burnetii are asymptomatic or result in mild transient flu-like illness.  Serious infections result in permanent cardiac injury; fortunately this is rare.  The number of organisms shed from aborting ewes and goats is enormous.  People are readily infected by aerosol.  The agent persists an extended time in the environment.  Ticks play a role in transmitting the disease in nature. There is a good recent review of Q fever in JAVMA.

VACCINE: NO

ANTIBIOTICS: YES - long-acting antibiotics such as tetracycline in water reduce shedding of the organism but there have been no studies to determine whether they can clear infection. 

7.  Brucella melitensis in goats

I mention this not because it is common in the US, but since it is one of the nastier form of brucellosis you can get from animals.  It is diagnosed periodically in some states (California, Florida, Texas).  We have not seen it in Wyoming (when we were cleaning out a storage room some years ago, we found a dried up vial labeled as B. melitensis.  The vial looked old, and out of curiosity we tried to culture it.  To our astonishment, it came up on culture.  This is a reflection of the relative hardiness of the organism).   It causes abortion in late term does, and can be shed in milk.

8.  Brucella ovis  - contagious epididymitis

Preventing abortion in sheep and goats

• VACCINATE: there are effective vaccines for both chlamydial and vibrionic abortion - a combined product is made by the Colorado Serum Company.  It is unusual to see a break due to "Vibrio" in vaccinated flocks. This suggests the vaccine is effective.

• CARE INTRODUCING PREGNANT EWES: this is a major way to introduce disease.  Make sure that the source flock does not have a history of abortions storms in the previous 3 years.  Additional belt-and-braces is to keep newly purchased pregnant ewes separate until after lambing from the main flock.

• LAMB EWE LAMBS SEPARATELY FROM EWE FLOCK.  Ewe lambs are often the most naive, and are particularly susceptible to chlamydiosis.

• FEED EWES from bunks: fecal sources of infection are important for vibrio, chlamydiosis, and salmonellosis.

• CONTROL CATS - keep them away from feed and lambing pens.  Cats are the main source of toxoplasmosis, and can be an especial problem in intensive operation where they can defecate into feed bins.

• CONSIDER FEEDING TETRACYCLINE-LACED FEED in herds with a recurrent problem with Chlamydia abortion.

• WHEN TOXOPLASMOSIS IS A RECURRENT PROBLEM, include a COCCIDIOSTAT in the ration (e.g., Rumensin or Deccox).

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Goiter

Goiter means non-neoplastic, non-inflammatory enlargement of the thyroid gland.  There are two major causes in our area: low iodine in the diet, and inherited forms.  Goiter occurs in multiple species, but we most commonly see it in goats > sheep > cattle.   Boer goats, a meat breed that grows fast, seems especially prone to goiter.  It is a fairly common cause of perinatal death in kids, in my experience.  Goats and other affected species have characteristic swellings (due to large thyroid glands) immediately behind the jaw as shown in the image below.  The typical presentation is a weak, thinly haired newborn with a marked swelling immediately behind the angle of the jaw.  Affected kids and lambs generally die.  The diet should be analyzed for its iodine content and, if low, supplemental iodine fed.

Goiter in a newborn goat kid.  The skin has been excised, exposing the large thyroid gland.  In Wyoming we most commonly see this in Boar goats, presumably related to rapid rates of growth.

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Dealing with an abortion outbreak

• GET A DIAGNOSIS!  Submit dead lambs AND PLACENTA to a diagnostic laboratory.  This generally takes a 1 week to get an answer back.  In some of these diseases, the placenta is the main or only place in which the organism will be found.

• FIND AND DISPOSE OF INFECTED MEMBRANES AND FETUSES IMMEDIATELY AND SAFELY.  Most  infectious material is in the placenta and fetal fluids.  Wear gloves and a calving gown, and disinfect the contaminated area if it is in a pen.  Aborted tissues should be buried or burnt.

• SEGREGATE EWES or EWE LAMBS THAT HAVE ABORTED.  Such animals continue to shed infectious agents for several days and should be quarantined for at least a week (if EAE, 6 weeks).

• Depending on the diagnosis you can either VACCINATE in the face of the outbreak (will slow down a vibrio abortion) or TREAT all pregnant ewes with antibacterial agents (tetracycline for Campylobacter; tetracycline, sulfa drugs or whatever the laboratory isolates are sensitive to, for Vibrio).  This will not stop losses immediately but will reduce the overall impact of the abortions.

Diseases in nursing lambs

1.  Hypothermia/hypoglycemia

This is the number one killer of lambs - many losses blamed on predation represent weak, dying and dead lambs that have been recycled by coyotes and foxes.  When lambs are born, they have limited body fat and, when it is wet and cold, they develop hypothermia rapidly.  Light lambs have a higher surface area and chill quickly.  Normal body temperature for lambs is 99 - 102 F.  Hypothermic lambs rapidly become recumbent and comatose.  When we see these guys at necropsy, there are not much to see: sometimes there is early pneumonia and the lambs have lost their brown fat.

Moderate hypothermia (temperature >99°F) in a lamb less than 5 hours old.  In most cases a lamb this young will still have some energy reserve and, therefore, glucose administration will not be necessary. The lamb should first be vigorously towel-dried and then given colostrum. If it can nurse, encourage it; if not, feed 2 ounces by stomach tube at two hour intervals. The lamb need not be warmed with more than a heat lamp in a draft-free claiming pen.

Severe hypothermia (temperature less than <99°F) in a lamb less than 5 hours old. The lamb should be dried and warmed - rapid warming important. This can be done by putting the lamb into warm (104 F) water or by using a warming box.  If the lamb is flat out (approaching coma), it also needs glucose.  This is best given using sterile technique and injecting a 20% glucose solution into the abdominal cavity.  Once the lamb’s rectal temperature reaches the normal range (99°F). it should receive colostrum, as before.

For lambs that are older than 24 hr., hypothermia usually is a result of starvation. Without energy from milk lambs become hypoglycemic, hypothermic, then die. Treatment for these situations is similar to that used for the newborn, with the exception that older lambs need not receive colostrum. Milk replacer can be fed with a bottle or tube fed. As a guideline, these older lambs should receive 6-8 oz. of warm milk.

2.  Diarrhea

There are several major causes of diarrhea in nursing lambs.  The most important are:

a.  E. coli

E. coli scours are an opportunistic disease associated with dirty environmental conditions and poor sanitation. It generally occurs as a diarrhea problem in two to four-day-old lambs. Affected lambs salivate and have a cold mouth; thus the common name, "watery mouth."  Dehydration, coma and death usually occur within 12-24 hours following onset of clinical signs of scours. Treatment of E. coli scours usually involves rehydrating lambs with oral, subcutaneous or intraperitoneal fluids and treatment with appropriate antibiotics. Prevention of E. coli scours in lambs should be an important goal for any flock. Lambing barn sanitation and creating a clean dry environment for newborn lambs are important for preventing outbreaks of E. coli scours.

b.  Clostridium perfringens

As in calves, Clostridium perfringens is causes death in newborn and nursing lambs.  One strain (Clostridium perfringens type C) affects the very young lambs (<2 weeks of age).  They present with bloody diarrhea.     It is often related to indigestion and predisposed by a sudden change in feed such as beginning creep feeding or an abrupt increase in milk supply. Treatment (antitoxin injected under skin) is usually unrewarding Vaccination of pregnant ewes 30 days before lambing is recommended as prevention.  The other form is seen in older lambs and is the classical "overeating disease".  It is due to Clostridium perfringens type D and most commonly strikes large fast-growing lambs. It is caused by a sudden change in feed that induces the organism, which is already present in the lamb's gut, to proliferate.   It is most commonly observed in lambs consuming high concentrate rations.  It can also occur when lambs are nursing on heavy milking dams. It usually affects lambs >1 month old.  Vaccination of pregnant ewes 30 days before lambing is the best preventative.  The best source of control is: 1. hygiene; 2. vaccinate dam at pregnancy; 3.  consider vaccinating young lambs when losses are heavy (alternatively, provide immunoglobulin)

c.  Salmonellosis

Salmonellosis can cause diarrhea in all ages; the circumstances in young lambs are similar to those in calves. It also can cause outbreaks of diarrhea late in pregnancy and in this situation is accompanied by abortion. Salmonellosis is more common when sheep or goats are congregated intensively or stressed, particularly by shipping.

Note: Parasitic diseases tend to occur in lambs older than 1 month, the only exception being cryptosporidiosis as early as 1 week of age.  Unlike calves, viruses are not a major recognized cause of diarrhea in lambs.  We have seen rotaviral outbreaks in kid goats.  Coccidiosis tends to be seen in lambs >1 month, and may occur with nematodiriasis in our area.

3.  Pneumonia

Pneumonia often occurs because of a lack of colostrum, because of "mastitis milk," or because ewes are heavily infected with Pasteurella multocida (99% are infected in their upper respiratory tract without disease, so the organism is always present). A lamb contracts pneumonia because it can't stand stresses such as too little milk, draft, dampness, and ammonia off the manure pack.   Diagnosis of sick, unthrifty young lambs is relatively simple: most of the time they are either starving or have pneumonia. Strive for early detection and start antibiotic treatment before the lungs are permanently damaged.   Treatment for pneumonia is to inject the lamb with antibiotics (tetracycline, penicillin, or streptomycin) plus one grain sulfamethazine per pound of body weight. Adequate selenium and vitamin E help lambs withstand pneumonia.

Selected diseases in peripartum and recently lambed ewes

1. Pregnancy toxemia

Drs. Montgomery and Fox touched on this in their lectures.  Pregnancy toxemia is a metabolic disease affecting ewes in late gestation. It most commonly afflicts thin ewes, overfat ewes, and/or older ewes carrying multiple fetuses. It is caused by inadequate intake of energy during late pregnancy, when the majority of fetal growth occurs.  The subsequent metabolic changes result in excessive lipid mobilization, especially in the liver.  Cold weather, poor feed quality, and environmental stress induce a state of negative energy balance and increase the risk of pregnancy toxemia.  Affected ewes are typically lethargic, go off food, and may be dehydrated.  There is a simple dipstick test for ketone bodies, which are metabolites that occur in urine.  Clinical signs of depression in a fat, late-gestation ewe with twins or triplets should trigger a strong suspicion of pregnancy toxemia.  Treatment is to increase the blood sugar supply to the body by administering propylene glycol or molasses orally, or dextrose solution intravenously. In extreme cases, removal of the fetuses by induced abortion is the only recourse to save the ewe. Pregnancy toxemia can be prevented by providing adequate energy to ewes during late gestation, approximately 1 kg of cereal grain/d (2.2 lb cereal grain/d). Adequate feeder space is necessary so that all ewes  consume enough feed.   Affected ewes must be detected early (within a day) of clinical signs, otherwise they are hard to save.  Other treatment options are to do a Caesarian section or to abort the lambs using corticosteroids.

2.  Mastitis

Mastitis is an inflammation of the mammary gland (udder) caused by bacterial infections up the teat canal.  Trauma, fecal contamination and teat conformation are factors. Important bacteria causing mastitis in ewes are Staphylococcus aureus and Pasteurella haemolytica. Note that the latter is the cause of pneumonia in lambs, and is a normal inhabitant in the respiratory tract, mouth and pharynx of sheep.  There are two types of mastitis: acute and chronic. The glands of ewes with acute mastitis may be discolored, dark, swollen and warm (bluebag). The affected ewe may be reluctant to walk, may hold up one rear foot, and may not permit the lambs to nurse. Ewes with chronic mastitis often go undetected.  Severe chronic mastitis with scar tissue formation (hardbag) is a reason for culling. Active mastitis is treated with intramammary infusions of antibiotics and systemic antibiotics. There is no vaccine for mastitis so it is best prevented by good management and sanitation.

3.  Prolapse

Prolapse is a major cause of ewe mortality. Ewes, and especially ewe lambs, that are fat and aren't getting exercise, are most susceptible. Moldy feed that contains estrogen may upset hormone balance sufficiently to cause expulsion of the vagina or uterus.

Vaginal prolapse occurs before lambing and may be inherited. It may be due to too bulky feed, natural estrogens in the feed or those produced by molds, a tail dock that is too short, or injury. To correct it, clean the protruding tissue, elevate the rear quarters of the ewe, and reinsert the tissue. To keep the tissue in, you can suture the vulva partially, insert a plastic retainer, or fasten a hitch around the ewe in a manner that permits tying three knots across the vulva. Use an antibiotic to arrest infection.  If she survives, cull the ewe.

 Uterine prolapse occurs after lambing and may be due to a parturition accident. It may never occur again. If uterine infection develops, treat it with sulfa bolus or an antibiotic. Use a ewe retainer, feed a low roughage diet, elevate the ewe's rear quarters, and use a rope hitch if necessary

4.  Ringwomb

This is term used to describe when the cervix does not dilate during parturition.  The cause of ringwomb is unknown but may be due to a lack of release of hormones involved in softening collagen or a lack of response of the collagen in the cervix to hormonal stimulation.  There is no correlation of ringwomb with breed of sheep, age, and body condition score. But there does appear to be a genetic correlation to ringwomb; the occurrence of ringwomb appears to run win bloodlines and when these bloodlines are inbred, the frequency of ringwomb increases.

Affected ewe, left unassisted, fail to have a fully dilated cervix.   Placental membranes protrude from the vagina, but the lamb(s) is held in the uterus and dies from hypoxia.  The ewe requires assistance to deliver the dead fetus. The dead lambs rot in situ, leading to septicemia and death of the ewe. Ewes found at this critical stage should be given antibiotics to prevent systemic infection, and dead lambs removed by caesarean section.  Affected ewes and any female offspring should be culled, since this appears to have a major genetic components.

For those of you interested in sheep diseases from a management standpoint, the University of Sydney's veterinary school has an excellent on-line text for veterinary students on diseases of sheep.  Some allowance should be made for its Australian origins.  The information about diseases in sheep is pertinent to the American West - it is a pity that some of the energy that the Australian sheep industry puts into disease control is not copied here.

Dr. Donal O'Toole

04/05/2010