COMMON SHEEP DISEASES: RECOGNITION, PREVENTION & MANAGEMENT
PARASITIC DISEASES HAEMONCHUS CONTORTUS (BARBER POLE WORM)
The greatest economic parasite in U.S. sheep. Blood-feeding abomasal worm causing anemia, bottle jaw, and death. Requires integrated management: FAMACHA scoring, targeted selective treatment, pasture rotation, and genetic selection. Avoid routine whole-flock deworming to slow resistance. COCCIDIOSIS
Protozoan infection primarily affecting lambs, causing diarrhea and poor growth. Risk increases with overcrowding, wet bedding, and stress. Prevent through sanitation, reduced stocking density, and strategic coccidiostat use during high-risk periods.
Coccidiosis - Credit: www.nadis.org.uk
REPRODUCTIVE DISEASES CHLAMYDIAL ABORTION
One of the most common infectious causes of late-term abortion. Ewes abort in the last 2–3 weeks of gestation. Spreads through infected placental membranes and discharge. Vaccination of ewes before breeding is highly effective. Isolate aborting ewes and clean up birth products immediately. CAMPYLOBACTER ABORTION (VIBRIOSIS)
Produces late-term abortion or weak lambs. Transmitted through contaminated feed, water, or aborted material. Pre-breeding vaccination of ewes significantly reduces losses. Prompt removal of aborted material during lambing is critical. RESPIRATORY DISEASES PNEUMONIA
Chlamydia - Credit: hipra.com/en/animal-health/ knowledge
Caused by a combination of stress, viral infection, and secondary bacteria (Mannheimia, Pasteurella). Poor ventilation, overcrowding, and ammonia buildup are major predisposing factors. Early antibiotic treatment is effective. Keep ammonia below 25 ppm and minimize handling/transport stress.
KEY TAKEAWAYS
Vaccination (CDT, Chlamydia, Vibrio) is the most cost-effective prevention tool. Biosecurity—quarantine, closed flock, sanitation— limits disease introduction. Chronic diseases (OPP, Johne’s, CLA) have no cure; focus on testing and culling.
Parasite control requires strategic management to slow resistance. Sound nutrition and body condition monitoring across all production phases directly reduce metabolic and reproductive disease risk. Emergency conditions (marked in red) require immediate veterinary intervention.
*Reference guide only and is not a substitute for veterinary care.
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