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Abortive salmonellosis
Abortive salmonellosis is caused by a particular salmonella, adapted to sheep, which attacks lambs at the end of gestation. Other less specialized salmonella can give a similar picture. It differs from other causes of abortion by one point...
What is it?
Abortive salmonellosis is caused by a particular salmonella, adapted to sheep, which attacks lambs at the end of gestation. Other less specialized salmonella can give a similar picture. It differs from other causes of abortion by one point that breeders notice immediately: the ewe is sick, too. Fever, depression, refusal to eat often accompany abortion, and some females die. Abortions occur in the last weeks of gestation. Lambs are also born alive but too weak and die in the first days, sometimes with diarrhea. As with any series of abortions, it is impossible to know what it is without analyzes: brucellosis, Q fever, abortive chlamydia, toxoplasmosis and campylobacteriosis give similar pictures, and some threaten the health of the family.
Key point
Unlike most causes of sheep abortion, this disease can kill the mother. A ewe that aborts with a fever or remains lying down should be seen by the veterinarian the same day.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Cluster abortions in the last weeks of gestation, affecting both young ewes and adults.
Ewe frankly ill at the time of abortion or just before: fever, depression, refusal to eat, isolation from the flock.
Abundant, dirty brown, often smelly vulvar discharge that lasts for several days.
Frequent retained placenta, followed by infection of the uterus.
Diarrhea in some affected ewes.
Ewe mortality, which is rare in other causes of abortion and should always be a warning.
Lambs born alive but weak, which do not suckle and die within a few days, sometimes with diarrhea.
At the herd level, the episode can be brief and brutal, with many abortions in a short period of time.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The bacteria settles in the sheep's intestine, passes into the blood and then into the placenta, where it causes inflammation which kills the lamb.
It can also make the sheep itself sick, which explains the fever and mortality of females.
Cured ewes remain carriers and eliminate the bacteria without becoming ill: they maintain the infection in the flock from one year to the next, often without us knowing it.
The conditions which weaken ewes at the end of gestation favor the appearance of the disease: undernutrition, transport, sudden changes in ration, overcrowding, cold and humidity in the sheepfold.
A sheep that aborts eliminates massive quantities of bacteria and contaminates its peers, which triggers the wave.
Last third of gestation, especially the last month.
Overcrowded sheepfold, damp and rarely renewed litter, insufficient ventilation.
Insufficient or unbalanced diet at the end of gestation, thin ewes.
Transport, groupings, purchases and market returns just before lambing.
Introduction of animals without quarantine, in particular pregnant females.
Presence of carrier ewes from a previous episode, often unknown to the breeder.
Dirty drinking water, shared drinking bowls never cleaned.
Climatic stress, damp cold or excessive heat in buildings.
Transmission
Contamination occurs through the mouth: water, food, fodder and litter soiled by droppings or by the products of an abortion.
Abortions, placentas and discharges are extremely contaminating: they are what fuel the epidemic in a lot.
Carrier ewes without signs are the most difficult source to spot and explain recurrences from one campaign to another.
Equipment, boots, hands, troughs and wheelbarrows move the bacteria from one pen to another.
Rodents, birds and farm dogs can contribute to the spread.
Human beings are mainly contaminated by dirty hands placed in their mouths and raw milk.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
A sheep that aborts and is sick at the same time must call the veterinarian the same day: its condition can deteriorate quickly.
Keep the abortion and placenta cool, in a closed bag, without touching them with bare hands. These are the samples that will help identify the cause.
The veterinarian has these samples analyzed in the laboratory, as well as blood samples from several ewes in the flock. It systematically screens for other causes of serial abortion, including brucellosis, Q fever, abortive chlamydia, and toxoplasmosis.
He examines the affected sheep: temperature, state of hydration, appearance of discharge, condition of the uterus.
In the event of a sheep death, examining the dead animal provides decisive information: do not make it disappear before speaking to the veterinarian.
Finally, he evaluates the breeding conditions, because this disease is more pronounced when the ewes are crowded, poorly fed or stressed.
Treatment
Sick sheep need rapid treatment: antibiotic chosen by the veterinarian, anti-inflammatory if necessary, rehydration and general support.
A feverish, dehydrated or lying down sheep after an abortion is an emergency: every hour counts.
In the middle of a wave, the veterinarian can decide on collective treatment of females that are still pregnant. This decision is entirely up to him and depends on the confirmed cause.
Never give an antibiotic on your own initiative and do not copy an old prescription: this distorts the analyses, delays the diagnosis and promotes bacterial resistance.
Lambs born weak need warmth, rapid colostrum and close supervision; What to do in case of diarrhea is decided with the veterinarian.
Waiting times for meat and milk must be requested systematically and respected, particularly before any sale or slaughter.
The immediate isolation of ewes which have aborted and the collection of the runts weigh as much as the medication in the outcome of the episode.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Isolate any sheep that aborts, immediately and until the discharge stops.
Collect abortions and placentas with gloves, in a closed bag, and have them disposed of according to regulations.
Remove soiled litter, disinfect, mulch generously and avoid damp areas in the sheepfold.
Reduce the density of lambing flocks: overcrowding is a major triggering factor.
Pay attention to feeding during the last third of gestation, a period when needs explode and a thin ewe becomes vulnerable.
Avoid transportation and sudden changes of ration or batch in the last month.
Quarantine any purchased animals and do not introduce pregnant females of unknown origin just before lambing.
Protect food from rodents and birds, clean drinkers and troughs regularly.
In farms that have already experienced an episode, discuss vaccination with the veterinarian before the next control season.
Vaccination
A vaccine against the salmonella responsible for ovine abortion exists and is used in certain countries. Its availability varies according to regions and periods: only the veterinarian can say what is really accessible.
When available, it is used before pregnancy, to protect the herd, and not as a treatment in the midst of a wave of abortions.
The schedule, the timing of the fight and the animals to be vaccinated are defined by the veterinarian based on the history of the farm.
Vaccination never replaces lambing hygiene: in an overcrowded building where runts remain on the ground, it will not be enough.
Possible complications
Death of the sheep by generalized infection, which distinguishes this disease from most other causes of abortion.
Severe infection of the uterus after abortion, with risk of permanent infertility.
Significant mortality of lambs born alive but weakened.
Installation of carriers in the herd, with recurrence of abortions in subsequent campaigns.
Contamination of the sheepfold environment, difficult to clean up.
Heavy economic losses: dead or culled sheep, lost lambs, compromised countryside.
When to see a veterinarian
A ewe aborts and at the same time presents with fever, depression or refusal to eat: call the same day.
Multiple abortions occur within a short period of time in the same batch.
A sheep dies after an abortion or in the days following it.
Abundant, foul-smelling vulvar discharge persists.
Lambs are born alive but do not suckle and die within a few days.
Diarrhea appears in ewes at the end of pregnancy.
A person who participated in lambing has fever and diarrhea: they must consult a doctor and report contact with animals.
Transmission to humans
The salmonella specifically responsible for ovine abortion is not considered an important human germ, but one never knows, at the time an abortion is discovered, which bacteria is involved. Other salmonellas present in farming cause serious food poisoning in humans.
The rule is therefore the same as for all abortions: you never handle an abortion, a placenta or soiled litter with your bare hands. Gloves, closed bag, then careful hand washing with soap.
Do not consume raw milk from a sick or aborted sheep, and do not give it to children.
Pregnant women should stay away from lambing and aborted ewes: several other causes of ewe abortion are dangerous to human pregnancy.
Children should not play in the lambing area during a bout of abortions, and sheep clothing should not be brought into the house.
Prognosis
A ewe treated early generally recovers, but those with a generalized infection or a severe infection of the uterus have a guarded prognosis.
Cured ewes can remain carriers and recur the disease the following year: this is what makes recurrences frequent.
The current lambing campaign is most often seriously compromised.
In the medium term, the prognosis depends on the sanitation of the building, feeding at the end of gestation and, when possible, vaccination before the next fight.
Frequently asked questions
How do I know if my abortions come from this disease rather than another?
Only through analyses. There is one clue, however: here, the sheep is often sick itself, with fever, and some die, which is rare in other causes. But only the laboratory decides, and the course of action to be taken depends on the result.
Can I keep a ewe that has aborted for breeding?
This is a decision to make with the veterinarian. Some females remain carriers and can rekindle the disease the following campaign. In farms that experience recurrences, sorting females is part of the solution.
Does a vaccine exist?
A vaccine against salmonella responsible for ovine abortion exists and is used in some countries. Its availability varies: ask the veterinarian what is available at your home. It arises before the struggle, never in the middle of a wave of abortions.
Is my sheep's milk suitable for consumption during an episode of abortion?
Raw milk from a sick or aborted sheep should not be consumed or given to children. Furthermore, any milk produced during treatment and during the waiting period set by the veterinarian must be discarded.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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