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Caseous lymphadenitis
Caseous lymphadenitis, commonly called abscess disease, is a chronic bacterial infection very widespread in sheep and goats, in Tunisia and throughout the Maghreb. It forms abscesses in the lymph nodes, especially those located under the sk...
What is it?
Caseous lymphadenitis, commonly called abscess disease, is a chronic bacterial infection very widespread in sheep and goats, in Tunisia and throughout the Maghreb.
It forms abscesses in the lymph nodes, especially those located under the skin: at the trough, in front of the shoulder, on the side, at the udder. The pus is thick, greenish and odorless, with a characteristic flaky appearance.
An internal form exists, less visible: abscesses develop in the lungs, liver or chest lymph nodes. The animal slowly lost weight without anyone understanding why.
Key point
Very widespread and underestimated disease because it kills few people. Its cost is mostly invisible: animals that die off, carcasses seized, breeding stock depreciated.
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:
Firm then soft, painless lump, under the skin, in the places where the lymph nodes are located: under the jaw, in front of the shoulder, on the side, at the level of the breast or testicles.
The abscess grows slowly for weeks, then may burst and leak thick, greenish to yellowish-white pus, without a bad odor.
The animal often remains in good general condition at the beginning: this is what causes the disease to be underestimated.
In the internal form: progressive weight loss despite a good appetite, decline in condition, animal falling behind the herd.
Cough, difficult breathing or shortness of breath on exertion when the lungs or chest lymph nodes are affected.
Reduced milk production when the udder or its lymph nodes are affected.
An abscess in an awkward position (throat, armpit) can cause difficulty swallowing or lameness.
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 disease is caused by the bacteria Corynebacterium pseudotuberculosis.
It enters through a wound, even a tiny one: a shearing cut, a scratch on a fence, a castration or dehorning wound, a bite, or the sting of soiled equipment.
Once entered, it reaches the nearest lymph node and forms an abscess there. From there, it can diffuse through the circulation to the deep organs.
The bacteria survives for a long time in the environment, particularly in dried pus, dust, litter and wood barriers.
Mowing carried out without disinfection of the blades between animals, and poorly contained animals which cut themselves.
High density herds, buildings with sharp corners, damaged fences, wire.
Serial interventions (castration, dehorning, marking) with non-disinfected equipment.
Purchases without prior examination or quarantine.
Elderly animals: prevalence increases with age, with abscesses accumulating over the years.
Lack of sorting: keeping an animal in the group with an open abscess contaminates everyone.
Transmission
By shearing equipment: the blades pass from one animal to another and carry the bacteria from one cut to the next. This is the most important mode of contamination.
By the pus from a burst abscess, which soils the litter, the walls, the scrubbers, the feeders, the neighbors' wool.
By castration, dehorning, branding equipment, reused needles, halters and ropes.
By direct contact between animals, especially when they rub against the same points.
By the introduction of a purchased animal carrying an undetected abscess, or carrying invisible internal abscesses.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian palpates all the superficial lymph nodes, which often allows the disease to be recognized based on its appearance and location.
A puncture of the contents of the abscess, sent to the laboratory, confirms the identity of the bacteria. This action must be done properly, with single-use equipment, to avoid further contamination.
A blood test for antibodies helps assess the situation of the herd and identify animals carrying internal forms.
Faced with unexplained weight loss without visible abscess, the veterinarian also thinks about this disease and other causes of chronic wasting in sheep.
Treatment
The treatment is disappointing, and you should know this before committing: the thick shell of the abscess prevents antibiotics from reaching the bacteria. General treatment alone almost never sterilizes a formed abscess.
The management of a mature superficial abscess involves drainage carried out by the veterinarian: opening, complete evacuation of the pus, antiseptic rinsing. The pus is collected and removed, never left on the ground.
An antibiotic may be prescribed in addition, in particular to prevent spread and superinfections, upon decision of the veterinarian.
The animal must be isolated for the duration of the discharge, and the premises used disinfected.
Internal forms cannot be treated effectively: culling is often the most reasonable decision, for the animal as well as for the herd.
Never puncture an abscess yourself in the middle of the herd: this is the action that contaminates the most.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Equipment hygiene is the central point. Disinfect shearing blades regularly, and systematically after an animal with an abscess. Mow healthy animals first, suspects last.
Use clean and disinfected equipment for castration, dehorning, marking and injections; do not reuse needles from one animal to another.
Isolate any animal that has a lump or abscess, and keep it away from the herd as long as it is leaking.
Eliminate pus and soiled dressings, disinfect the area used: dried pus remains contaminating for a long time.
Remove harmful objects from buildings and parks: wire, nails, splintered wood.
Examine and quarantine any animal purchased, palpating lymph nodes before introduction.
Cull animals with repeated abscesses: they maintain contamination of the herd.
Wearing gloves to handle an abscess or its pus, and washing your hands afterwards: this is a basic rule of hygiene for working in livestock farming.
Vaccination
Vaccines exist in certain countries, alone or combined with protection against enterotoxemia. They reduce the number of new abscesses and the severity of cases, but do not cure already affected animals or clean up a herd on their own.
Their availability varies depending on the country: check with your veterinarian, who will tell you what can be used locally and whether it is justified in your situation.
Vaccination only makes sense when accompanied by hygiene of mowing equipment and sorting of carrier animals.
Possible complications
Chronic weight loss and lasting decline in internal forms.
Lung abscesses leading to shortness of breath and exercise intolerance.
Decreased milk production and udder abscess.
Partial or total seizures at the slaughterhouse, with direct economic loss.
Depreciation of wool and skin.
Rams affected in the testicles: reduced fertility.
Diffusion to the entire herd when abscesses break through without being isolated.
When to see a veterinarian
You feel a lump under the skin, especially under the jaw, in front of the shoulder or on the side.
An abscess is about to burst or is already leaking.
Many animals have lumps in the same places, especially after shearing.
An animal gradually loses weight without obvious cause, with a preserved appetite.
An animal coughs or becomes out of breath with exertion and loses condition.
An abscess appears on the udder or testicles of a breeding animal.
Prognosis
The disease rarely kills, but it is difficult to eliminate from a herd once established: the carrier animals, invisible internal abscesses and the resistance of the bacteria in the environment explain its persistence.
A properly drained superficial abscess heals locally, but the animal may develop others.
Internal forms have an unfavorable prognosis: the animal slowly wastes away.
The herds which obtain results are those which combine rigorous shearing hygiene, isolation of carriers and culling of recurrent cases, over several years.
Frequently asked questions
Can I pierce the abscess myself?
This is strongly discouraged. A carelessly burst abscess spreads highly contaminating pus onto bedding, barriers and other animals, and this is how the disease spreads. Have it done by the veterinarian, with the animal isolated, the pus collected and eliminated, and the area disinfected.
Why do abscesses come back after mowing?
Because mowing creates small cuts and the blades carry the bacteria from one animal to the next. Disinfecting the blades and shearing the carrying animals last completely changes the situation.
Can an antibiotic make the abscess go away?
Rarely. The thick shell of the abscess prevents the medicine from reaching the bacteria. The antibiotic has its place in addition to drainage or to limit the spread, but it does not replace the procedure and does not sanitize the herd.
Should affected animals be eliminated?
This is a decision to be made with the veterinarian, depending on the number of animals concerned and the value of the subjects. Animals with repeated abscesses or chronic wasting disease maintain contamination and are the first candidates for culling.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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