Home › Animalia › Animal health › Animal diseases › Ovine listeriosis

bacterial disease Sheep, Goat Transmissible to humans

Ovine listeriosis

Listeriosis is a bacterial disease feared by sheep farmers, both because it kills quickly and because it is dangerous for humans. The bacteria responsible lives naturally in soil, water and decaying plants. It has a particularity that expla...

Find a veterinarian All sheep diseases

Definition Signs Causes Transmission Diagnosis Treatment Prevention Complications When to see a vet Zoonosis Prognosis FAQ Sources Affected species

What is it?

Listeriosis is a bacterial disease feared by sheep farmers, both because it kills quickly and because it is dangerous for humans.

The bacteria responsible lives naturally in soil, water and decaying plants. It has a particularity that explains almost everything: it multiplies very well in the cold and in low-acid environments. This is why it proliferates in fermented fodder that is poorly preserved, earthy, moldy or in contact with air.

Elle prend chez le mouton trois visages très différents. The nervous form, which breeders call dizziness, is the most spectacular. The abortive form affects pregnant ewes. The generalized form mainly kills lambs.

Key point

Nervous listeriosis kills within a few days and can only be treated effectively if we intervene at the first signs. A sheep running in circles with an ear or eyelid drooping to one side is a veterinary emergency, and suspect fermented forage should be removed from the flock's ration the same day. It is also a serious zoonosis for pregnant women.

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:

Head tilted Circling Staggering gait Excessive salivation Difficulty swallowing Paralysis Closed or half-closed eye Discharge from the eyes Fever Abortion Lying animal that does not get up Reduction

Nervous form, the best known: the animal moves away from the herd, appears dazed, leans its head against a wall, then begins to always turn in the same direction.

The head is tilted to the side and the paralysis affects only one half of the face: one ear falls off, one eyelid no longer closes, the lip hangs, the eye tears and eventually ulcerates because it is no longer protected.

Abundant salivation and difficulty swallowing: the animal keeps grass pellets in the cheek, lets its tongue hang out, can no longer drink properly.

Staggering gait, falls, then animal lies down, always pushing on the same side, unable to get up.

Fever at the beginning, often already subsided when the breeder becomes worried.

The progression is rapid: from a few days to less than a week, and without early treatment the outcome is almost always fatal.

Abortive form: abortions at the end of gestation, often with retained placenta and infection of the uterus, in ewes which may not remain ill.

Generalized form: slaughtered lambs, refusing to suckle, feverish, which die in one to three days.

An ocular form also exists, with a red, watery and cloudy eye, in animals which immerse their heads in a contaminated rack.

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 is present everywhere in the environment: soil, dust, stagnant water, decomposing plants, droppings of animal carriers.

It multiplies massively in poorly preserved fermented fodder: silage or wrapping that is too earthy, poorly packed, poorly closed, started too slowly, exposed to the air, moldy or frozen. Insufficient acidification is enough to open the door.

The animals swallow the bacteria with the fodder.

In the nervous form, it takes a very particular path: it enters through small wounds in the mouth, particularly during teething or after a change of food, then goes up along the nerves of the face to the brainstem. It is this rise on one side which explains the facial paralysis on one side and the dizziness always in the same direction.

In pregnant sheep, the bacteria enters the bloodstream, reaches the placenta and kills the lamb.

Cold, humidity, deficiencies and the stress of changing rations favor the appearance of cases.

Distribution of fermented fodder: silage, wrapping, wet bales. This is the number one factor.

Silo poorly packed, poorly closed, started too slowly, leading edge exposed to the air, bales pierced by birds or rodents.

Fodder harvested too short, loaded with soil.

Moldy hay or straw, stored in a damp room.

Distribution on the ground, in the mud, or in racks that have never been cleaned.

Cold and wet season, sheepfold period.

Last third of gestation, period when ewes are most vulnerable.

Young animals in the process of teething, which have small sores in the mouth.

Sudden changes in ration, transport, shearing, groupings.

Deficiencies and animals in poor general condition.

Transmission

The main source is food: poorly preserved fermented fodder, very earthy hay, soiled food on the ground.

Direct contamination from one sick animal to another is marginal: when several animals become ill, it is almost always because they all eat the same thing.

The carrying animals eliminate the bacteria in their droppings, which maintains its presence in the building and on the plots.

Abortions, placentas and discharge from ewes that have aborted are very contaminating, for other animals as well as for people.

Human beings are mainly contaminated by eating contaminated foods, in particular raw milk and raw milk cheeses, and by direct contact with abortion products.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

A sheep running in circles must be seen quickly: several very different diseases give this sign, and they are not treated in the same way.

The veterinarian performs a complete nervous examination. Two elements strongly point it towards listeriosis: the paralysis of only one side of the face, with drooping ear and eyelid, and the rapid progression over a few days, often in several animals at the same time.

Coenurosis, parasitic whirling disease, on the contrary sets in slowly, over weeks or months, does not cause a fever, does not affect the face in this way and almost always affects an isolated animal. This distinction changes everything, because listeriosis is treatable if we intervene early.

The veterinarian also rules out other causes of nervous disorders in sheep: enterotoxemia, deficiencies, poisoning, inner ear damage, other infections.

He is systematically interested in food and asks to see the silo, the wrapped bales and the storage area: this is often where the answer is found.

In the event of an abortion, he has the abortion and the placenta analyzed, kept cool in a closed bag and handled with gloves.

Examining a dead animal confirms the diagnosis and allows rapid action on the rest of the herd.

Treatment

Nervous listeriosis can be treated, but only if we intervene very early: at the first signs, not when the animal is lying down. This point makes all the difference between healing and loss.

Treatment is based on a suitable antibiotic, administered quickly and continued for a sufficiently long time, combined with an anti-inflammatory. The choice of products, route and duration falls exclusively to the veterinarian, because the bacteria is lodged in the brain and not all antibiotics reach it.

Treatment that is too short or stopped as soon as improvement leads to relapses: this is a common error.

Supportive care is crucial: quiet shelter, thick bedding to avoid injuries, regular turning of a lying animal, provision of water and liquid food if the animal can no longer swallow, and protection of the eye which no longer closes.

An animal that can no longer swallow should not be drenched by force: it will inhale the liquid and develop pneumonia. Ask the vet how to feed it.

The first collective action is to immediately remove suspect fodder from the ration of the entire herd. Continuing to distribute it is making the following cases.

The waiting periods for meat and milk must be requested from the veterinarian and strictly respected.

The prognosis for animals already lying down is very guarded: euthanasia must be discussed to avoid long agony.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Everything depends on the quality of the fodder. Successful fermented fodder, well packed, well closed, harvested without soil and consumed quickly enough is the best vaccine against this disease.

Discard and never distribute moldy, earthy, heated, smelly fodder, or a punctured bale: doubt should always benefit the animals.

Regularly advance the leading edge of the silo to prevent air from settling there, and close carefully.

Do not pick up rejects from the ground to redistribute them.

Clean the racks and troughs, do not distribute on the ground in the mud.

Avoid sudden changes in ration and too rapid dietary transitions.

Store hay and straw in a dry place, out of reach of rodents and birds.

Immediately separate any animal showing nervous signs and call the veterinarian.

Isolate ewes that have aborted, collect aborts and placentas with gloves and have them disposed of according to regulations.

Protect storage areas and water points from bird droppings.

On farms where the disease returns every winter, the problem is almost always in the way the fodder is stored: this is where you need to look with the veterinarian.

Possible complications

Death of the animal within a few days when treatment is started too late.

Permanent nervous after-effects in animals that survive: persistent head tilt, difficulty eating, weight loss.

Ulcer then loss of the eye which no longer closes.

Inhalation pneumonia in animals that no longer swallow, aggravated by attempts at forced watering.

Relapse after shortened treatment.

Abortions, uterine infection and infertility in ewes affected by the abortive form.

Lamb mortality in generalized form.

Human contamination, particularly serious in pregnant women.

When to see a veterinarian

A sheep runs in circles, keeps its head tilted or leans its forehead against a wall: call the same day, treatment is only effective if it is started early.

An ear or eyelid droops to one side, the lip hangs, the animal drools.

An animal keeps grass in its cheek and is no longer able to swallow or drink.

Several animals from the same batch show nervous disorders in a short time.

An affected animal is already lying down and no longer gets up: you must decide quickly with the veterinarian.

Abortions occur in ewes fed fermented fodder.

Lambs die within one to three days after stopping suckling.

A person who has handled sick animals or runts has a fever, especially if they are pregnant: medical advice without delay.

Transmission to humans

Listeriosis is a serious zoonosis. This is one of the diseases for which precautions in the sheepfold are not a formality.

Human contamination occurs mainly through food: raw milk, raw milk cheeses, products poorly stored in the refrigerator. It can also occur through direct contact with abortions, placentas or sick animals, with in this case lesions on the skin of the hands and arms.

In a healthy person, the infection often remains mild. In pregnant women, it can cause abortion, premature birth or very serious infection of the newborn, even though the mother hardly feels ill. In elderly and immunocompromised people, it can affect the brain.

Rules to be respected without exception: pregnant women do not take care of lambing, do not touch abortions or placentas, do not approach sick animals and do not consume raw milk or raw milk cheese.

Never handle an abortion or placenta with bare hands, wear gloves, wash your hands thoroughly with soap afterwards, and do not bring sheep's clothing and boots into the house.

Do not consume raw milk from a sick or aborted sheep; the bacteria continues to multiply in the cold, refrigeration does not protect.

Any unexplained fever in a person working in contact with the herd should lead them to consult a doctor and report this contact.

Prognosis

An animal treated at the very first signs, still standing and able to swallow, has a real chance of healing, sometimes with a slight residual head tilt.

An animal already lying down, which no longer swallows, has a poor prognosis despite treatment.

The generalized form of the lamb is very often fatal.

Sheep in the abortive form generally recover, but may have uterine after-effects.

At the scale of the herd, everything depends on the food source: removed in time, the episode stops; maintained, cases follow one another for weeks.

Frequently asked questions

My sheep is going in circles: is it listeriosis or parasitic whirling disease?

Both exist and look similar from a distance, but they do not behave the same. Listeriosis progresses over a few days, is often accompanied by fever and paralysis on one side of the face, with drooping ears and eyelids, and frequently affects several animals from the same flock. Coenurosis sets in slowly, over months, in an isolated animal. Listeriosis can be treated if we intervene early: this is reason enough to call the veterinarian the same day.

Should I throw away all my silage?

Not necessarily, but any fodder that is moldy, earthy, heated, smelly or from a punctured bale should be discarded without hesitation. The veterinarian will help you examine the silo, the attack front and the method of conservation. Continuing to distribute suspicious fodder while treating an animal is to prepare for the following cases.

Is my sheep's milk dangerous?

Raw milk from a sick sheep or one that has just aborted should not be consumed, and raw milk cheeses are strictly not recommended for pregnant women, young children and fragile people. The bacteria even multiplies in the refrigerator: the cold does not provide shelter. Any milk produced during treatment must also be discarded according to the waiting period set by the veterinarian.

My wife is pregnant, what precautions should I take?

She must not take care of lambings, not touch aborts or placentas, not approach an animal suffering from nervous signs, and not consume raw milk or raw milk cheese. This illness can cause her to have an abortion or a serious infection in the newborn when she barely feels sick. Shepherding clothing and boots must remain outside.