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Necrotizing stomatitis of the lamb
Necrotizing stomatitis is an infection of the lamb's mouth by a bacteria which normally lives in the environment of the sheepfold, on soiled floors, and in the digestive tract of ruminants. This bacteria is unable to cross healthy mucous me...
What is it?
Necrotizing stomatitis is an infection of the lamb's mouth by a bacteria which normally lives in the environment of the sheepfold, on soiled floors, and in the digestive tract of ruminants.
This bacteria is unable to cross healthy mucous membranes. It needs an entry point: a small wound on the cheek, tongue or gum, caused by coarse and pungent fodder, by teething, by handling, by an ill-suited bottle or by lesions from another disease.
Once established, it destroys the tissues in depth, creates ulcers covered with a gray or yellowish deposit, and gives off a very recognizable putrid odor as soon as the animal is approached.
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:
Abundant salivation, often the first sign noticed: the lamb drools, the hair on the chin and chest remains wet.
Very marked putrid odor from the mouth, perceptible from a distance and absolutely characteristic.
Ulcers in the mouth: hollow sores on the inner side of the cheeks, on the tongue, on the gums or the palate, covered with a gray or yellowish deposit which adheres.
Pain: the lamb chews cautiously, drops food, refuses roughage, stops sucking.
Difficulty swallowing, regurgitation of poorly chewed food.
Swelling of the cheek or face, sometimes on only one side, with a hot and painful area.
Fever, despondency, lamb lying aside.
Weight loss and cessation of growth, very rapid at this age.
When the infection goes down to the larynx: noisy breathing, difficulty breathing, coughing, which considerably worsens the prognosis.
Several lambs from the same batch are often affected, which indicates a housing or feeding problem.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Infection by bacteria present in the environment, particularly in soiled litter, muddy floors and damp areas of sheepfolds. It is the same bacteria that is involved in foot rot and some liver abscesses.
An injury to the mucous membrane of the mouth is essential for it to take hold: this is the key point of the disease.
These injuries come from rough, dry and prickly fodder, thistles, cereal beards, foods too hard for the age, teething, unsuitable pacifiers and bottles, rough handling during drenching or the administration of products by mouth.
They can also be caused by another disease: contagious ecthyma, foot-and-mouth disease or peste des petits ruminants damage the mouth and open the way to this secondary infection.
A lamb that has not received enough colostrum defends itself less well and develops more serious forms.
Overcrowding, humidity, lack of ventilation and lack of cleaning increase microbial pressure in the building.
Soiled, damp, uncleaned litter and poorly ventilated buildings.
Overcrowding in lambing pens and lamb lots.
Distribution of rough, pungent or dusty fodder to lambs that are too young.
Lambs raised by bottle with poorly cleaned equipment or unsuitable teats.
Repeated handling of the mouth: administration of oral products without precaution, incorrectly used probes.
Lambs having received too little colostrum or too late.
Teething period.
Presence of contagious ecthyma or another disease creating oral lesions in the herd.
Lambs weakened by diarrhea, deficiency or parasitism.
Transmission
The bacteria is permanently present in the breeding environment: there is no classic contagion from a sick lamb to a healthy lamb, but a common exposure.
The affected batches are therefore affected because they share the same conditions: same litter, same fodder, same building.
Sick lambs, however, enrich the environment with bacteria through their saliva and their lesions, which increases the pressure on the others.
Poorly cleaned common equipment, including pacifiers, bottles and probes used to administer products by mouth, contributes to the spread.
This disease is not transmitted to humans.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Quickly show a lamb that is drooling and whose mouth smells bad: the disease progresses quickly at this age and a lamb that is no longer suckling becomes weaker in one or two days.
The veterinarian opens the mouth and carefully examines the cheeks, tongue, gums and palate, which is often enough to recognize the characteristic lesions.
He checks if the infection spreads to the larynx and lungs, which completely changes the prognosis, and listens to the breathing.
It rules out other causes of oral lesions in lambs, which is crucial: contagious ecthyma, which is a viral disease transmissible to humans, foot and mouth disease and peste des petits ruminants, which are regulated diseases requiring notification. Never conclude alone when faced with a damaged mouth.
Samples can be taken in case of doubt or when several lambs are affected.
The veterinarian then examines the building, the litter, the fodder distributed and the nursing equipment: this is where the real cause and the lasting solution are found.
Treatment
Treatment is based on antibiotics, prescribed by the veterinarian, and it gives good results when started early. The choice of molecule and duration cannot be improvised.
Treatment of pain and inflammation is generally combined, on prescription: a lamb in pain does not eat, and it is the lack of food that kills it.
Local mouth care, with a suitable antiseptic indicated by the veterinarian, completes the treatment. Do not use any caustic products or home remedies on already destroyed mucous membranes.
Feeding is essential: offer soft, easy-to-swallow foods, remove spicy fodder, and assist the lamb which is no longer suckling. The veterinarian can insert a tube and show how to feed the lamb while you wait.
Isolate the affected lamb on clean, dry bedding, under cover, with accessible water.
Forms descending towards the larynx and lungs require intensive care and have a guarded prognosis.
Above all, immediately correct the cause: clean and mulch, remove the fodder in question, clean the nursing equipment. Without this, new lambs will become ill in the following days.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Maintain clean, dry and abundant litter in lambing pens and batches of lambs: this is the most effective measure, and at the same time resolves other diseases of the young.
Drain regularly, avoid damp and muddy areas, ventilate without creating drafts on the lambs.
Avoid overcrowding in huts.
Adapt the fodder to the age: no coarse, spicy or shaggy fodder for young lambs.
Systematically clean and disinfect pacifiers, bottles and oral administration equipment between animals.
Handle the lambs' mouths gently when administering products, and have the veterinarian demonstrate the procedure rather than force.
Guaranteeing sufficient and early colostrum intake: this is what gives the lambs the means to defend themselves.
Monitor flocks daily: a drooling lamb should be examined the same day.
Treat cases of contagious ecthyma in the herd quickly, wearing gloves, because these lesions open the door to this infection.
Possible complications
Extension of the infection to the larynx and lungs, with serious pneumonia and a very guarded prognosis.
Passage of the bacteria into the blood, with abscesses of the liver and other organs.
Weight loss and growth retardation that cannot be recovered.
Death of the lamb, due to generalized infection or simply because it is no longer eating.
Deformation or loss of tissue in the mouth in the most affected animals, with lasting difficulty in eating.
Appearance of new cases in the lot as long as the litter and fodder are not corrected.
When to see a veterinarian
A lamb is drooling and its mouth gives off a putrid odor: consult the same day.
A lamb refuses to suckle or eat, drops food, chews cautiously.
You see hollow sores and a gray or yellow deposit in the mouth: do not conclude alone, other serious and regulated diseases cause oral lesions.
A lamb's cheek or face is swollen.
A lamb is breathing noisily or has difficulty breathing: emergency, the infection is coming down.
Several lambs from the same batch have mouth lesions: the building and fodder must be examined without delay.
Prognosis
Caught early, with appropriate treatment, oral care and assisted feeding, the lamb generally recovers well.
Extensive forms, with swelling of the face or damage to the larynx and lungs, have a guarded prognosis and some lambs die.
Lambs that were very emaciated before treatment often have lasting growth retardation.
On a batch scale, the prognosis depends entirely on the correction of the building and the fodder: the disease disappears when the litter becomes clean and dry again, and it returns every year if nothing changes.
Frequently asked questions
My lamb is drooling and his mouth smells very bad, what is it?
This putrid odor associated with salivation is very suggestive of necrotizing stomatitis. The lamb must be examined the same day: the infection can go down to the lungs and, above all, a lamb which no longer suckles weakens in one or two days.
Is it contagious to my other lambs?
Not in the classic sense: the bacteria is already present in the litter and in the building. If several lambs are affected, it is because they share the same conditions, not because they have contaminated each other. It is therefore the litter and fodder that must be corrected, in addition to treating the sick.
Can I put disinfectant or home remedy in my mouth?
No, not on your own initiative. An already destroyed mucous membrane cannot tolerate caustic products, which aggravate the lesions and the pain. The veterinarian will indicate a suitable antiseptic and prescribe the necessary antibiotic treatment.
Am I risking anything by caring for this lamb?
This infection is not transmitted to humans. On the other hand, other diseases cause oral lesions in lambs and some, such as contagious ecthyma, are transmitted well to humans. This is another reason to wear gloves and have the diagnosis made by the veterinarian.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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