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Sheep scrapie
Scrapie is a disease of the nervous system of sheep and goats that slowly destroys the brain. It belongs to the family of spongiform encephalopathies: the nervous tissue develops tiny cavities and takes on the appearance of a sponge under t...
What is it?
Scrapie is a disease of the nervous system of sheep and goats that slowly destroys the brain. It belongs to the family of spongiform encephalopathies: the nervous tissue develops tiny cavities and takes on the appearance of a sponge under the microscope.
The causative agent is neither a microbe nor a parasite. It is an abnormal protein, called a prion, which has the particularity of deforming the normal proteins it encounters, step by step, until it ruins the brain. This protein resists heat, ordinary disinfectants and time: it survives for years in a building or in the ground.
The disease progresses over years before it is seen. The animal is infected young, most often around birth, and shows nothing for a very long time. The signs generally appear in adults several years old, and the progression is then inexorable.
Key point
Fatal disease, without treatment and notifiable. A sheep that scratches without responding to parasiticides is not necessarily mangy: talk to the veterinarian, do not sell it or make it disappear.
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:
The first signs are changes in behavior, often perceived by the breeder well before they can be named: animal which isolates itself, which becomes anxious or on the contrary aggressive, which reacts exaggeratedly to noise, dogs or handling, which no longer lets itself be approached as before.
Then comes scratching, which gives its name to the disease in several languages. The animal rubs against fences, walls, feeders, posts, chews its sides and hindquarters, tears off wool in patches, especially on the back, sides and rump. The skin often remains intact underneath, which is a clue.
A very evocative sign: when the animal is scratched on the back or rump, it tenses its neck, raises its head and makes lip and jaw movements, almost trembling with pleasure. This reflex does not exist in normal sheep.
Tremors of the head and neck, especially after exertion or emotion.
Abnormal gait: animal which raises its front legs high, which stumbles, which staggers from behind, which no longer clears an obstacle correctly, which falls and gets up with difficulty.
Progressive weight loss while the animal continues to eat, until a state of extreme thinness.
Grinding teeth, staring, animal moving away from the herd.
In the last weeks: repeated falls, animal lying down which no longer gets up, then death.
The progression is always downward, without ever improving, over several weeks to several months.
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 an abnormal protein, the prion, which accumulates in the nervous system and in certain organs.
This protein resists conditions that destroy all ordinary microbes: it is not eliminated by usual disinfectants, nor by usual heat, and persists for a very long time in the environment of a contaminated sheepfold or pasture.
Susceptibility to disease is highly dependent on the animal's genetics. Some genetic profiles are practically resistant, others very sensitive. It is this discovery which has made it possible, in several countries, to build selection programs on resistance to scrapie.
Contamination occurs mainly around birth, in contact with the placenta and the lambing fluids of a carrying ewe, in a lambing room where the prion has accumulated.
The animal infected when young will not express the disease until years later, which makes the chain difficult for the breeder to see.
Purchase of animals, particularly breeding ewes and rams, from flocks of unknown status.
Sensitive genetic profile in herd animals.
Lambing grouped in a single room, reused from year to year without the possibility of effective disinfection.
History of cases on the farm or in the neighborhood.
Mixture of herds, common pastures, loans of rams.
Lack of traceability and identification of animals, which prevents tracing of filiations when a case appears.
Transmission
Contamination occurs mainly from the ewe to the lamb, at the time of lambing: the placenta and the birthing fluids of a carrying ewe are the most contaminated sources.
The environment plays a major role. A lambing room, a bedding area, a pasture where carrying ewes have given birth remain contaminating for years, even after the animals have left. A sanitized herd can therefore become recontaminated by reusing the same buildings.
The introduction of carrier animals, purchased from an affected herd, is the classic way of entering an unaffected farm. As the carriers do not show anything for years, the appearance of the animal does not provide any information.
There is no transmission by insect bite, nor by simple proximity at a distance.
According to current knowledge, classical scrapie in sheep is not considered transmissible to humans. This does not exempt you from respecting the usual hygiene rules and the instructions of the veterinary services, which strictly regulate this disease.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
No examination on a living animal alone allows the diagnosis to be made with certainty in current breeding.
The veterinarian first relies on the clinical picture: an adult who loses weight, scratches without skin lesions explaining the scratching, staggers and changes in character, with a progression that only gets worse.
He methodically rules out other causes, which is essential because several of them can be treated: scabies and other external parasites, melophagosis, deficiencies, intoxication, the disease of old age which is weight loss due to poor teeth, coenurosis, listeriosis, brain abscesses and chronic viral diseases of sheep such as maedi-visna.
Confirmation is made after death, by examination of the brain in an approved laboratory. This is why you should never make a suspicious animal disappear without speaking to the veterinarian: the carcass is the only piece of evidence.
Suspicion must be reported. The veterinarian takes charge of this process with the veterinary services, which define the conduct to be followed for the herd.
Genetic typing of breeding stock can be proposed as part of resistance selection programs.
Treatment
There is no treatment. No antibiotic, no antiparasitic, no supplement, no preparation modifies the course of the disease.
An affected animal always progresses towards death within a few weeks to a few months.
Antiparasitic treatments given because the animal is scratching are useless here: the scratching comes from the brain and not the skin. Continuing to treat an animal that does not respond for scabies should on the contrary make people think of this disease and trigger a call to the veterinarian.
The action to be taken is not medical but regulatory: report the suspicion to the veterinarian, do not move the animal, do not sell it, do not get rid of it without instruction, and follow the instructions of the veterinary services.
Euthanasia, decided in this context, avoids a long and painful end of life and allows confirmation of the diagnosis.
Selling a suspect animal or discreetly removing it from the farm is the worst decision: the disease then moves to another herd, and the breeder is exposed to sanctions.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Buy breeding stock, and especially rams, from farms with known health status, and find out about existing qualification programs in the country.
When selection programs for genetic resistance exist, favor rams carrying resistant profiles: this is the most effective lever known to date, and it acts on all offspring.
Separate lambings: do not lamb all the ewes in the same premises year after year, clean and remulch between batches, quickly remove placentas and lambing fluids rather than leaving them on the litter.
Do not have a lamb adopted by a ewe from another flock, and be wary of animal exchanges between farms.
Correctly identify animals and keep a register of parentage: without this, it is impossible to manage a case if it arises.
Report any suspicion: it is an obligation, and it is also the only way to protect other farms in the region.
Never reuse a contaminated sheepfold for lambing without seeking advice from the veterinary services: ordinary disinfectants have no effect on the prion.
Vaccination
There is no vaccine against scrapie and it is unlikely that one will exist, as the causative agent is not a typical microbe against which the body produces antibodies.
The only known lasting protection is genetic: the selection of breeders carrying resistant profiles, within the framework of official programs where they exist.
Possible complications
Evolution always fatal in the affected animal.
Falls, wounds and lesions of the skin due to rubbing, with secondary infections and myiasis in the hot season.
Extreme weight loss and painful end of life if the animal is not taken care of.
Silent spread in the herd for years before the first visible case appears.
Long-lasting contamination of lambing buildings, with cases continuing to appear long after.
Regulatory and commercial consequences for the farm, with movement restrictions and the impossibility of selling breeding stock.
When to see a veterinarian
An adult sheep scratches, rubs and loses its wool without antiparasitic treatments changing anything.
He is losing weight even though he eats normally.
His character changes: he becomes fearful, aggressive, or jumps at the slightest noise.
He trembles, staggers, raises his paws high or stumbles.
He makes lip movements when his rump is scratched.
He ends up falling and never getting up again.
An animal shows several of these signs which get worse week after week: call the veterinarian, do not sell the animal or get rid of it yourself.
Prognosis
The individual prognosis is zero: the disease is constantly fatal and without treatment.
At the flock level, everything depends on the speed of the declaration and the implementation of measures: genetic selection, lambing management and purchasing control make it possible, over several years, to clean up a farm.
Farms that close their herds and select for resistance obtain the best long-term results.
Frequently asked questions
My sheep is scratching and losing its wool, is it scabies or scrapie?
The two look very similar at first glance and only the veterinarian can decide. An important clue: in scabies, the skin is damaged, crusty and the antiparasitic treatment is effective. In scrapie, the skin is often healthy under the torn wool, treatments do not change anything, and the animal loses weight and changes character at the same time.
Can I eat meat from a sheep in my flock if a case is suspected?
It is not up to you to decide: as soon as a suspicion exists, the course of action to be taken is determined by the veterinary services, which supervise slaughter and consumption. Call the vet and follow their instructions rather than killing on your own.
Is there a treatment or a vaccine?
Neither, and we must not let ourselves be sold a miracle solution. The only known truly effective lever is the selection of genetically resistant breeding stock, when a program exists in the country. Talk to your veterinarian before your next ram purchase.
Why does the sheepfold remain contaminated after the animals leave?
Because the agent of the disease is not an ordinary microbe: it is an abnormal protein which resists common disinfectants and heat, and which persists for years in litter or soil. This is why lambing must be managed carefully and the reuse of contaminated premises must be discussed with the veterinary services.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
EFSA — Autorité européenne de sécurité des aliments
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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