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Ovine anaplasmosis
Anaplasmosis is caused by a very small bacteria that lives inside the red blood cells of sheep and goats. The parasitized red blood cells are identified and then destroyed by the body itself, mainly in the spleen. The animal gradually finds...
What is it?
Anaplasmosis is caused by a very small bacteria that lives inside the red blood cells of sheep and goats.
The parasitized red blood cells are identified and then destroyed by the body itself, mainly in the spleen. The animal gradually finds itself lacking blood: it turns pale, it runs out of breath, it no longer follows.
The disease is transmitted by ticks, but also by anything that passes a drop of blood from one animal to another: a reused needle, a shearing blade, a castration or buckling knife.
Key point
A very anemic sheep may die from simply being caught or transported. In front of white mucous membranes, we treat the animal on the spot, without running or loading it.
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 pallor of the mucous membranes: the inside of the lower eyelid, the gums and the vulva change from deep pink to pale pink then to white. This is the most constant sign.
Yellow coloring of the mucous membranes and sometimes the white of the eye, which appears a few days after the pallor: the blood destroyed en masse releases a pigment that the liver is no longer able to evacuate.
Urine remains clear or normal. This is an important point: their normal color does not rule out the disease.
Fever at the start of the episode, often unnoticed because it precedes the other signs.
Animal which stays behind the herd, which often stops, which blows after a few meters of slope.
Rapid breathing and a fast heartbeat, even at rest.
Weight loss, dull wool, marked drop in milk production in lactating females.
In severe forms, lying animal which no longer gets up; some die from the slightest effort, for example during gathering, sorting or transport.
In young animals, the infection often goes completely unnoticed: they become immune without being noticed.
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 responsible bacteria enters the red blood cells and multiplies there without causing them to burst directly.
It is the animal's defense reaction that does the damage: the spleen eliminates the red blood cells marked by the bacteria, in very large numbers, faster than the bone marrow can produce them.
As the destruction takes place in the organs and not in the vessels, hemoglobin does not pass into the urine: this is the reason why the urine maintains a normal color.
A cured animal remains a carrier for a long time, often for life, without becoming ill. It constitutes a reservoir: the ticks which bite it leave loaded and contaminate the rest of the herd.
Crises appear especially when a carrier animal is weakened by something else: birth, undernutrition, transport, other illness, heavy worm load.
Tick season and areas: bushy paths, forest edges, hedges, low walls, old sheepfolds whose cracks harbor ticks.
Introduction of animals from a region with ticks into a herd that has never been exposed: these naive animals develop the most serious forms.
Adult animals that have never encountered the bacteria: unlike many diseases, it is the adults here who pay the heaviest price, with the young becoming discreetly immunized.
Reuse of needles during vaccinations and herd treatments, shearing and castration equipment not cleaned between animals.
Period around giving birth and lactation, transport, high heat, undernutrition: anything that weakens can awaken a dormant infection.
Associated internal parasitism, in particular the red abomasum worm, which also causes anemia and considerably aggravates the picture.
Gatherings, fairs, transhumance and periods of heavy animal movement such as the weeks preceding Eid.
Transmission
By ticks, firstly: the tick gorges itself on a carrier animal then inoculates the bacteria into the next animal. The risk therefore follows the tick season, in spring and autumn in our regions, with an increase after the rains.
By blood, mechanically: a single needle used on several animals, a shearing blade, a castration knife, a curling or dehorning instrument are enough to transport enough blood to contaminate.
By biting flies and horseflies, which carry blood from one animal to another during interrupted meals.
From the mother to the lamb during gestation, in some cases.
There is no contagion through simple contact, nor through sharing a water trough or a feeder.
The disease is not transmitted to humans and the meat of an affected animal does not present a risk as a result.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines the color of the mucous membranes of several animals in the group, not just the one that alerted, and looks for the yellow tint on the mucous membranes and the white of the eye.
He checks the color of the urine: this is the point which determines between anaplasmosis and babesiosis, two diseases transmitted by the same ticks but which are not treated with the same products.
A blood test allows you to measure the depth of the anemia and, on a colored smear examined under a microscope, to directly see the bacteria inside the red blood cells.
More in-depth laboratory analyzes exist to confirm the species in question and identify carrier animals without signs.
The veterinarian systematically looks for other causes of sheep anemia, which are very common in our farms: internal parasites, liver fluke, deficiencies. Several can coexist in the same animal.
Examining a dead animal is useful: a very enlarged spleen and clear, liquid blood are highly suggestive.
Treatment
The treatment uses a particular family of antibiotics, active on bacteria that live inside cells. Antibiotics commonly used against respiratory infections or lameness have no effect here: this is a common and time-consuming error.
The choice of product, route and duration is up to the veterinarian. No dose, no rhythm should be decided on your own initiative.
The earlier the treatment, the better the result: on an animal that is already lying down and very pale, the antibiotic alone is often no longer enough.
Supportive care is as important as medicine: shade, clean water within reach, palatable food, absolute rest. A very anemic animal may die simply from being chased, caught or transported. Handle it slowly, heal it on the spot.
A blood transfusion may be considered by the veterinarian on a valuable animal.
The treatment makes the signs disappear but does not always rid the animal of the bacteria: it often remains a carrier and serves as a reservoir for ticks. This is why tick control remains essential even after recovery.
The waiting times for meat and milk, indicated on the instructions for each product, must be strictly respected. Have them clarified by the veterinarian 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
Fighting against ticks is the main lever, and at the same time it protects against babesiosis, theileriosis and other diseases transmitted by the same bite. Anti-tick products exist in several families and in several forms, for external application or injection; the choice and the calendar are made with the veterinarian according to the season and the region.
Also treat buildings: some ticks spend part of their lives in the cracks of walls and under the feeders of old sheepfolds. Filling cracks and cleaning thoroughly complements animal treatments.
One needle per animal during vaccination or treatment campaigns: this is the cheapest and one of the most effective measures. Clean and disinfect shearing blades, castration knives and buckling equipment between animals.
Quarantine any purchased animal, examine it, rid it of ticks and speak to the veterinarian before releasing it to the herd.
Avoid bringing in adult animals that have never seen ticks during the high-risk season: this is the situation that produces the most serious crises.
Regularly monitor the color of the herd's mucous membranes, particularly when returning from range and after periods of high tick presence.
Control internal parasites and feed correctly: a well-fed animal with few parasites copes much better.
Possible complications
Death from anemia, often sudden and triggered by effort, gathering or transport.
Abortion in pregnant ewes and small and weak lambs at birth.
Collapse of milk production, which does not always rise in the same lactation.
Long-lasting weight loss and very slow recovery: the production of new red blood cells takes weeks.
Recurrences during weakening, in an animal that remains carrier.
Mutual aggravation with internal parasites: two causes of anemia in the same animal combine.
Increased susceptibility to all other herd diseases until the animal has rebuilt its blood.
When to see a veterinarian
The inside of the eyelid or the gums of an animal are pale or whitish: it is an emergency, do not postpone until tomorrow.
The mucous membranes or the white of the eye take on a yellow tint.
An animal blows at the slightest effort, stays behind the herd or refuses to get up.
Many animals become weak at the same time during or after tick season.
A recently purchased pet becomes ill within weeks of its arrival.
Animals go poorly after a vaccination or treatment campaign carried out with the same needle for the entire herd.
An animal dies suddenly during sorting, loading or transport: report it, this will direct the veterinarian.
Prognosis
An animal treated early, whose mucous membranes are still pink, recovers well, but it needs several weeks of good nutrition and calm to replenish its blood.
An animal already lying down, very pale and yellow, has a guarded prognosis even under treatment: the handling itself may be enough to kill it.
At the herd level, the prognosis depends on tick control and equipment hygiene: without this, cases recur each season, always on the most productive animals.
Cured animals most often remain carriers: they are fine, but they maintain the disease in the breeding area.
Frequently asked questions
My sheep is pale and yellow but his urine is normal: is it still a blood disease?
Yes, and this is exactly the profile of anaplasmosis. The blood is destroyed in the organs and not in the vessels, so the urine retains its color. Waiting for red urine to cause concern causes animals to lose.
Can you get this disease from eating meat?
No. This bacteria is not transmitted to humans. On the other hand, ticks picked up from animals can transmit other diseases to humans: wear gloves to remove them and never crush them between your fingers.
Why does the vet insist on needles?
Because a reused needle carries enough blood to contaminate the next animal. A vaccination campaign carried out with the same needle for the entire herd can trigger a series of cases a few weeks later. One needle per animal is the cheapest measure of all.
Are my cured animals free of disease?
Most often no. They are fine but remain carriers, sometimes for life, and the ticks that bite them contaminate others. This is why tick control remains necessary even in a herd that appears healthy.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
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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