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Esophagostomosis
Esophagostomosis is caused by a large intestinal roundworm called a lumpy worm because its larvae form hard nodules in the lining of the intestine. It is a particularity which makes this disease recognizable among all: when an animal is ope...
What is it?
Esophagostomosis is caused by a large intestinal roundworm called a lumpy worm because its larvae form hard nodules in the lining of the intestine. It is a particularity which makes this disease recognizable among all: when an animal is opened, the intestine is dotted with small hard balls, like grains under the finger, which give it a knotty appearance. These nodules are not just a curiosity: they hinder the functioning of the intestine, maintain inflammation and make the casings unfit for any use, which represents a concrete economic loss at the slaughterhouse. The disease mainly affects young animals and warm regions with a marked humid season. It is well known from sheep farms in North Africa. It is distinguished from other digestive worms by a sign that breeders often notice without associating it with parasites: a stiff gait, an arched back, an animal that walks with difficulty.
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:
Persistent diarrhea, often dark, sometimes with mucus, which permanently stains the hindquarters.
Marked weight loss and stalling growth in young people despite a correct ration.
Stiff gait, arched back, animal that moves with difficulty and stays behind the herd: this sign, linked to inflammation of the large intestine, is very evocative.
Efforts to defecate.
Paleness of the mucous membranes when the inflammation lasts.
Soft swelling under the jaw as proteins leak through the damaged intestine.
Dejection, reduced appetite, animals that graze little and remain lying down.
Dull, brittle wool that loses its value.
In chronic forms, the animal remains thin despite treatment and never completely recovers: the nodules do not disappear.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Adult worms live in the large intestine and lay eggs which come out with the droppings.
On the ground, in warmth and humidity, the eggs produce larvae which climb onto the grass and are swallowed by grazing animals.
Once swallowed, the larvae burrow into the wall of the intestine. The body reacts by locking them in: this is how nodules are formed, small hard balls sometimes filled with greenish pus.
In an animal already exposed before, the reaction is more violent: the larvae remain stuck in the nodules and the inflammation becomes significant. Paradoxically, it is sometimes the animals already sensitized that suffer the most.
The larvae that manage to emerge from the nodules reach the lumen of the large intestine and become adults.
The larvae can also pause in the wall during the unfavorable season, then move back together when conditions improve.
Young animals and animals in the first or second grazing season.
Hot regions with a marked wet season; periods following the rains.
Short grazing, high stocking rates, lack of rotation.
Irrigated plots and lowland wetlands.
Malnourished animals with protein deficiency: they develop much more severe forms.
Animals already exposed during a previous season, in which the reaction to the larvae is more intense.
Association with other digestive worms, very common, which aggravates the whole.
Transmission
Contamination occurs through grass, never by direct contact between animals, and this worm is not transmitted to humans.
The larvae need heat and humidity: the periods following the rains and irrigated plots are the most contaminating.
Areas where animals stay, around water troughs, shade points and distribution areas, are particularly loaded.
An animal introduced without quarantine can bring the parasite, and possibly resistant worms, to a farm.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian relies on the signs, particularly the combination of persistent diarrhea and stiff gait in young animals on pasture.
The analysis of droppings reveals the eggs, but they closely resemble those of other roundworms: a culture of the larvae is sometimes necessary to precisely identify the species in question. This has a practical interest, because the strategy is not the same depending on the dominant verses.
An important trap: when the larvae are stuck in the nodules and few adults are present, the analysis of droppings can be weakly positive even though the animal is suffering a lot. The result must therefore be interpreted in context.
The examination of a dead animal or the observation of the intestines at the slaughterhouse is the most demonstrative element: the nodules can be felt along the wall with a finger.
The slaughterhouse returns on the intestines constitute valuable monitoring information for the breeder: intestines regularly separated indicate a problem on the farm.
Treatment
Internal antiparasitics act on adult worms; the choice of family and form is up to the veterinarian, taking into account the species of worms present and the state of resistance in the region.
A limit must be understood: the larvae enclosed in the nodules are much more difficult to reach than the adult worms. A treatment can therefore clean the intestine without removing the nodules already installed, and the animal remains emaciated for a certain time.
No dose or rhythm is decided alone. Systematic treatment of the entire herd on a fixed date, without analysis, is not recommended: it is the main driver of resistance to antiparasitics, which also affects this parasite.
A check of the droppings after treatment makes it possible to verify that the product is still working on the farm.
Thin animals need a sustained diet, rich in protein, and rest; dewormer alone does not restore a condition.
Waiting periods for meat and milk must be requested before any slaughter or milking.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Rotate the plots and avoid short grazing, where the larvae concentrate.
Delay the entry of young animals onto wet or irrigated plots after the rains, the most contaminating period.
Reserve the healthiest plots for young growing plants.
Alternate with cattle or horses when possible.
Dry the areas around waterers and regularly move the fodder distribution points.
Quarantine and treat, on veterinary advice, any animal purchased before releasing it to pasture.
Ensuring a correct diet, particularly protein: this is a determining factor in the severity of this disease.
Follow the slaughterhouse returns concerning the casings and speak to the veterinarian if they are regularly discarded.
Manage treatments by stool analyzes rather than by calendar.
Possible complications
Permanent nodules in the intestinal wall, which persist after the disappearance of the worms and maintain poor digestion.
Chronic weight loss and animals that never recover, sometimes needing to be culled.
Leakage of proteins from the damaged intestine, with edema.
Anemia and general weakening.
Rupture or infection of a nodule, with inflammation of the abdominal cavity, serious situation.
Casings unfit for use and carcasses devalued at the slaughterhouse.
Aggravation by other digestive parasites, almost always associated.
When to see a veterinarian
Young animals have persistent diarrhea and lose weight despite good nutrition.
An animal walks stiffly, with its back hunched, and stays behind the herd.
Animals strain to defecate.
Pale mucous membranes or swelling under the jaw appear.
The slaughterhouse reports knotted or separated intestines on your animals: ask for advice even if the herd appears to be in good shape.
The condition does not improve after deworming: it is necessary to check its effectiveness and look for other parasites rather than giving it again.
Prognosis
Animals caught early, treated and well fed recover well.
Chronic forms, with numerous established nodules, leave animals which never completely recover: the nodules do not resolve and digestion remains impaired.
The young people affected in full growth keep a delay which weighs on the results of the band.
At the herd level, the prognosis depends on grazing management, feeding and the state of resistance to antiparasitics.
Frequently asked questions
My sheep walks stiff and has diarrhea: is it a joint problem?
This is not necessarily the case. The association of persistent diarrhea and a stiff gait, hunched back, in young animals grazing primarily suggests the lumpy worm, whose inflammation of the large intestine hinders walking. A veterinary examination and an analysis of droppings make it possible to decide.
The slaughterhouse told me that the casings were unusable, why?
Because the larvae of this worm form hard nodules in the wall of the intestine, which make it unsuitable for any use. It is a direct economic loss, and above all a signal: the parasite is indeed present on your farm and deserves to be discussed with the veterinarian.
I dewormed and my pet remains thin: has the product failed?
Not necessarily. The larvae enclosed in the nodules are difficult to reach, and the nodules already formed do not disappear with treatment. Recovery takes time and sustained nutrition. If no improvement appears, the veterinarian will check the effectiveness of the product by analyzing the droppings.
Is it contagious to my other sheep or my family?
Not from one animal to another directly: contamination passes through the larvae present on the grass. This worm is not transmitted to humans. Control therefore requires pasture management, not isolation of patients.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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