Treating anemia in sheep starts with identifying the cause, which in most cases is blood loss from internal parasites, particularly the barber’s pole worm. A single one of these worms drains about 0.05 ml of blood per day, and a heavy infection of 5,000 worms can pull 250 ml of blood daily, enough to cause severe anemia in a short time. Treatment combines deworming, nutritional support, and in critical cases, a blood transfusion.
Checking for Anemia With the FAMACHA System
The fastest way to assess anemia in the field is the FAMACHA eye color chart. You pull down the sheep’s lower eyelid and compare the color of the mucous membrane to a five-point scale ranging from deep red (score 1, healthy) to white (score 5, severely anemic). Scores of 3, 4, and 5 indicate anemia and warrant treatment. A score of 3 corresponds roughly to a packed cell volume (PCV) of around 23%, while scores of 4 and 5 reflect increasingly dangerous blood loss.
If you have access to a veterinarian or can run a simple blood test, PCV gives you a more precise picture. A PCV at or below 19% confirms clinical anemia. At 15% or below, the sheep is in serious trouble. At 10% or less, a blood transfusion becomes the treatment of choice. Animals with a PCV between 11 and 15 may benefit from a transfusion but can sometimes recover without one if treated promptly.
Identifying the Cause
The barber’s pole worm (Haemonchus contortus) is the most common culprit. It lives in the abomasum (the sheep’s true stomach) and feeds directly on blood. A fecal egg count can help confirm infection. In one study, sheep with a FAMACHA score of 3 had an average egg count of about 1,758 eggs per gram and worm burdens ranging from roughly 4,800 to 8,700 adult worms.
Liver flukes are another parasitic cause. Fasciola hepatica migrates through the liver, causing tissue damage and chronic blood loss. Signs include weight loss, poor appetite, and sometimes a swollen jaw from fluid accumulation. Diagnosis typically requires a fecal exam looking for fluke eggs or a blood antibody test. The key difference in treatment: standard dewormers used for roundworms do not kill liver flukes. Triclabendazole is the drug of choice for flukes, while praziquantel is not effective against them.
Nutritional deficiencies can also cause anemia without any parasite involvement. Cobalt deficiency is the classic example. Sheep need trace amounts of cobalt in their diet to produce vitamin B12, which is essential for making red blood cells. Without it, they develop anemia, lose weight, stop eating, and become progressively weaker. This is more common in regions with cobalt-deficient soils.
Deworming: Choosing a Drug That Still Works
Anthelmintic resistance is now widespread, and picking the wrong dewormer wastes precious time in an anemic animal. The older drug classes, including ivermectin, albendazole, and levamisole, have shown high resistance rates on sheep farms around the world. Ivermectin in particular has been reported as completely ineffective against gastrointestinal worms in many regions, largely from years of overuse.
Monepantel, a newer drug class (aminoacetonitrile derivative), has consistently shown 97 to 100% effectiveness in studies where other drugs failed. If you haven’t used it on your farm, it’s likely your best option for treating a heavily parasitized, anemic sheep. Your veterinarian can help you source it and confirm the correct dose for your animals’ body weight.
The only way to know which dewormers still work on your specific farm is a fecal egg count reduction test. You take fecal samples before treatment and again 10 to 14 days after, then compare egg counts. If the drug reduced egg output by less than 95%, resistance is present. Running this test with each drug class you use saves you from relying on products that are no longer effective.
Emergency Treatment for Severe Cases
A sheep that is recumbent, breathing rapidly, or has white mucous membranes needs more than a dewormer. When the PCV drops to 10% or below, a blood transfusion from a healthy donor sheep is the most effective intervention. The donor should be a healthy adult from the same flock, and ideally one that has not been recently dewormed (to avoid transferring drug residues). Your veterinarian can collect and administer the blood.
For animals between 11 and 15% PCV, supportive care without transfusion can work if you act quickly. This means deworming immediately, moving the sheep off contaminated pasture, providing high-quality feed, and keeping the animal calm to reduce oxygen demand on its depleted red blood cells. Stress, handling, or forcing a severely anemic sheep to walk long distances can be fatal because its blood simply cannot carry enough oxygen.
Nutritional Support During Recovery
After deworming, the sheep’s bone marrow needs 3 to 5 days just to begin ramping up red blood cell production. Full recovery takes much longer. Iron is essential for building new red blood cells, and most sheep get adequate iron from their diet, but offering good-quality hay and access to a mineral supplement helps ensure nothing is limiting recovery.
If cobalt deficiency is the underlying problem, vitamin B12 injections can produce dramatic improvement. In severely deficient sheep that had been on cobalt-poor diets for over 500 days, twice-daily vitamin B12 injections over 21 days brought hemoglobin levels back to normal within 40 to 60 days. For long-term prevention, cobalt can be provided through mineral blocks, drenches, or slow-release rumen boluses. The response to B12 supplementation in these studies was so consistent that researchers concluded it is the primary, and possibly only, limiting factor in cobalt-deficient sheep.
Copper Oxide Wire Particles as a Supplement
Copper oxide wire particles (COWP) are small copper rods given in a gelatin capsule that lodge in the abomasum and slowly dissolve, creating an environment hostile to barber’s pole worms. A dose of just 2 grams has been shown to reduce Haemonchus contortus egg counts and lower the number of egg-laying worms in the abomasum, while keeping liver copper levels relatively low compared to higher doses of 4 or 6 grams.
COWP is not a standalone dewormer and won’t rescue a severely anemic animal, but it’s a useful tool alongside chemical treatment. Be cautious with copper in certain breeds. Some sheep breeds, particularly those with more primitive genetics, are highly susceptible to copper toxicity. Always know your flock’s copper status before supplementing.
Pasture Management to Prevent Reinfection
Treating the sheep without managing the pasture is a losing strategy. Infective larvae sit on grass blades waiting to be consumed, and a dewormed sheep turned back onto heavily contaminated pasture will simply pick up a new infection within days.
Rotational grazing is the most effective non-chemical tool. Parasite larvae can survive on pasture for up to 120 days in cool, moist conditions, but they die much faster in hot, dry weather. During summer, rest periods of 65 days or more between grazings significantly reduce larval contamination. In cooler, wetter seasons, longer rest periods are needed.
Other strategies that help: grazing sheep behind cattle (cattle consume sheep larvae but aren’t harmed by them), keeping pasture height above 4 inches (larvae concentrate in the lower 2 inches of grass), and avoiding overstocking, which forces sheep to graze closer to the ground where larvae are densest. Combining these practices with selective deworming, treating only the animals that need it based on FAMACHA scores rather than blanket-treating the whole flock, slows the development of drug resistance and keeps your remaining effective dewormers working longer.