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Ovine pulmonary adenomatosis
Ovine pulmonary adenomatosis, known as jaagsiekte, is a particular disease: it is lung cancer caused by a virus, and therefore transmissible from one sheep to another. The virus causes the cells lining the lung alveoli to proliferate. The l...
What is it?
Ovine pulmonary adenomatosis, known as jaagsiekte, is a particular disease: it is lung cancer caused by a virus, and therefore transmissible from one sheep to another.
The virus causes the cells lining the lung alveoli to proliferate. The lung gradually fills with tumor tissue and clear, abundant fluid, which further reduces the surface area available for breathing.
Signs only appear after a long silent period, usually in adult sheep two to four years of age and older.
Key point
Always fatal disease, without treatment or vaccine, and without reliable screening test on live animals. Terminal respiratory distress requires a decision to be made in time, with the veterinarian.
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:
Progressive weight loss in an adult who maintains his appetite.
Increasing shortness of breath: the animal stays behind the herd, tires quickly, breathes more and more quickly, including when resting.
Liquid, clear, abundant, non-purulent nasal discharge. It increases significantly when the head is lowered: it is an orientation element used in the field.
Occasional cough, wet breathing sounds.
Absence of fever, unless a bacterial infection is added.
In advanced stages: animal which remains lying down, becomes exhausted at the slightest movement, breathes with its mouth open.
Affected animals often continue to eat until an advanced stage, which delays the concern of the breeder.
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 a retrovirus specific to sheep, which transforms cells in the lining of the pulmonary alveoli into tumor cells.
The resulting tumor is diffuse: it gradually invades both lungs rather than forming a single mass.
The abundant production of fluid in the respiratory tract accompanies this proliferation.
Between contamination and the appearance of signs, several years most often pass: a young infected animal shows nothing for a very long time.
Purchase of adult animals without knowledge of the status of the original herd.
Breeding in buildings with high density and long confinement period.
Herds with many older animals.
Prolonged cohabitation of undetected affected animals with the rest of the herd, due to lack of visible signs at an early stage.
Transmission
By respiratory route, between sheep in close contact: the liquid and secretions emitted by an affected animal contain the virus.
Promiscuity in buildings, prolonged wintering and high density significantly increase diffusion.
Transmission through colostrum and milk is also possible from mother to lamb.
The introduction of an infected animal but without apparent signs is the usual way the virus enters an unaffected herd.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian suspects the disease in an adult who is losing weight and is short of breath without fever, with a clear and abundant nasal discharge.
Examination of the lungs and observation of the animal head down guide the diagnosis in the field.
There is no reliable blood test to detect living animals: this is what makes this disease difficult to control, unlike others.
Imaging exams can be performed in certain structures.
The autopsy of a dead or culled animal gives the safest diagnosis and allows us to know what to expect for the rest of the herd.
The veterinarian rules out other causes of chronic respiratory difficulty in adult sheep, including Maedi-Visna, which gives a similar picture.
Treatment
There is no treatment: no antiviral medication, no surgery, no chemotherapy applicable in breeding.
Antibiotics are only of interest to treat an additional bacterial infection, on veterinary prescription; they have no effect on the tumor.
Evolution is inexorable once the signs appear.
The decision to shorten the suffering of an animal in respiratory distress is made with the veterinarian; allowing an animal to suffocate is not acceptable.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Avoid the introduction of animals of unknown origin; favor herds with a known respiratory history and without cases of chronic wasting.
Quickly eliminate animals that show the suggestive signs: they are the main sources of virus for the herd.
Limit density and improve ventilation of buildings, particularly during winter.
Reduce prolonged contact between batches and avoid unnecessary groupings.
In seriously affected herds, management in separate batches according to age, discussed with the veterinarian, limits the spread to younger generations.
Have animals that die of chronic respiratory problems autopsied: this is the only way to know if the disease is present.
Possible complications
Progressive respiratory distress leading to death.
Added bacterial pneumonia, which accelerates degradation.
Extreme weight loss and exhaustion.
Silent diffusion in the herd during the years preceding the appearance of the first visible cases.
Economic losses through adult mortality and breeding culls.
When to see a veterinarian
An adult sheep becomes out of breath and loses weight as it continues to eat.
A clear liquid flows abundantly from the nostrils, especially when the head is lowered.
An animal systematically stays behind the herd or refuses to move.
Several adults waste away with respiratory signs over the same period.
An animal has died of chronic respiratory problems: ask for an autopsy rather than dismissing the corpse without knowing.
Prognosis
The prognosis is fatal for the affected animal: once the signs have set in, the progression is towards respiratory distress within a few weeks to a few months.
No recovery is possible, no treatment changes the course of the disease.
At the herd level, the situation depends on the number of animals already infected, invisible due to lack of screening tests: when the first cases appear, other animals are generally already contaminated.
Control requires the rapid elimination of cases, vigilance when purchasing and the reduction of promiscuity.
Frequently asked questions
Is this cancer contagious?
Yes, and that's what sets it apart from most cancers. It is caused by a virus which is transmitted between sheep, mainly by respiratory route in buildings. An affected animal contaminates its fellow animals.
Is there a test to screen my animals?
There is no reliable blood test that can be used routinely on living animals. This is the main difficulty of this disease. The diagnosis is based on clinical signs and, certainly, on autopsy.
Is it the same as Maedi-Visna?
No, they are two distinct viral illnesses, even though they both cause shortness of breath and weight loss in adults. The clear and abundant nasal discharge is directed towards the jaagsiekte. The two can coexist in a herd, and only the veterinarian can sort things out.
Is the meat of an affected animal dangerous?
This virus is not transmitted to humans. A dying animal must nevertheless go through the normal regulatory channels and health inspection; Ask your veterinarian for advice before making any decision.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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