COMMON SHEEP DISEASES: RECOGNITION, PREVENTION & MANAGEMENT
INFECTIOUS DISEASES
CASEOUS LYMPHADENITIS (CLA) Chronic bacterial infection causing abscesses in lymph nodes and internal organs. Spreads via contaminated shearing equipment, feed, and direct contact with abscess material. Extremely difficult to eliminate once established. Control through culling affected animals, lancing abscesses in isolation, and sanitizing equipment. A vaccine is available for infected flocks. OVINE PROGRESSIVE PNEUMONIA (OPP) Slow-progressing lentiviral infection of the lungs, joints, udder, and nervous system. Transmitted primarily through colostrum and milk, and prolonged close contact. No treatment or vaccine exists. Control requires regular testing, removal of positives, and heat-treating colostrum. JOHNE’S DISEASE Causes thickening intestinal walls and reducing nutrient absorption. Leads to progressive weight loss and death. Infected animals test negative 60–75% of the time on a single test. No cure. Focus on biosecurity, repeated testing, and protecting lambs from fecal contamination. FOOT ROT / FOOT SCALD Contagious bacterial infection spreading rapidly in wet conditions. Both treatable and curable with commitment. Isolate affected animals, trim hooves, implement foot baths (zinc or copper sulfate), and use antibiotic therapy. Quarantine all new arrivals. SOREMOUTH (ORF) Johne’s Disease - Credit: Ohio State University (u.osu.edu).
Viral disease causing painful scabs around the mouth, nostrils, feet, and udder. Zoonotic (which means humans can contract it) — always wear gloves. Self-limiting, resolving in 2–4 weeks. A live- virus vaccine exists but should only be used in flocks where the disease is already present. ENTEROTOXEMIA Enterotoxemia (“overeating disease”) results from Clostridium overgrowth after sudden diet changes. Frequently fatal but highly preventable with CDT vaccination. Vaccinate ewes 2–4 weeks pre-lambing; lambs at 2 weeks with a booster at 30–60 days.
Soremouth - Credit: Ohio State University (u.osu.edu).
NUTRITIONAL & METABOLIC DISEASES PREGNANCY TOXEMIA (KETOSIS)
Metabolic emergency in late-gestation ewes with multiple lambs from negative energy balance. Over-conditioned and under-conditioned ewes are both at risk. Signs: depression, teeth grinding, laying around more than normal. Treatable only if caught early. Prevent by maintaining Body Condition Score (BCS) 3.0–3.5 through late gestation with adequate energy intake. WHITE MUSCLE DISEASE Selenium and/or Vitamin E deficiency affecting skeletal and cardiac muscle in lambs. Causes stiffness, weakness, and sudden
death. Highly preventable through Selenium/Vitamin E supplementation in the ewe’s late-gestation diet. Regional soil selenium levels should guide programs. POLIOENCEPHALOMALACIA (PEM) Thiamine deficiency causing blindness, head pressing, and star-gazing. Triggered by high-concentrate diets, sulfur toxicity, or sudden feed changes. Injectable thiamine is effective if given early. Prevent with gradual diet transitions.
Polio - Credit: Michigan State - www.canr.msu.edu
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