September 4, 2008

Common Sheep Diseases

Your veterinarian is the best source of advice on diagnosis and treatment. The following are key points about the most common diseases. They are in a rough order of occurrence in a flock.

  • Cause: Bacteria in the soil and in chronically infected feet.
  • Signs: Lame sheep; Sheep grazing on their knees.
  • Affects: All ages, and is worst in winter with wet ground.
  • Treatment: Trim excess horn being careful not to cut into the quick and cause bleeding; Use antibiotic spray; Put through footbath of copper sulphate or formalin and let drain on concrete before returning to paddock; Cull severe cases.
  • Prevention: Cull all persistently chronic cases.

Foot scald
  • Cause: Bacteria on long wet spring pasture.
  • Signs: Very lame lambs.
  • Affects: Mainly young lambs between docking and weaning when pasture is long and wet.
  • Treatment: Antibiotic spray or footbath is a lot of lambs are affected.
  • Prevention; Graze on shorter pasture.
Internal parasites
  • Cause: Different species of roundworms, tapeworms, lungworms, liver flukes.
  • Signs: Scouring, poor growth, ill thrift, hollow looking and anaemic.
  • Affects: All ages, but especially damaging in young growing sheep.
  • Treatment: Anthelmintic worm drenches, and management options e.g. alternative grazing with other species.
  • Prevention: Check with veterinarian to ensure correct diagnosis using Faecal Egg Counts (FEC) and correct product to use to avoid drench resistance in worms.
External parasites


  • Cause: Lice & keds which suck blood.
  • Signs: Wool on fences where sheep have been rubbing. Wool pulled out from rest of fleece.
  • Affects: All ages, mainly those with long wool.
  • Treatment: Use correct chemical pouron treatment, spray or dip;
  • Prevention: Check regularly for lice on skin at base of wool staple on shoulder. Shear if wool is long.
Blowfly strike
  • Cause: Maggots of different species of blowfly.
  • Signs: Sheep biting areas of skin; Wool falling out and bare sores. Wet patches on wool.
  • Affects: All ages but most often lambs when they are scouring. The Australian green blowfly will strike on any damp sweaty part of a lamb.
  • Treatment: Use correct chemical spray; Dag and shear.
  • Prevention: Check regularly when weather is hot and humid. Shear and treat with chemical as risks increase.
Metabolic disease (grass staggers)
  • Cause: Low blood magnesium. May accompany low calcium or low sugar.
  • Signs: Wobbly sheep when moved, or on ground shaking or dead.
  • Affects: Ewes around lambing, especially any carrying twins
  • Treatment: Feed mineral supplement; clinicals will need urgent Mg injection.
  • Prevention: Check blood status of sheep. Ensure good feed levels with good quality supplements (silage or hay) if pasture is short. Don’t let ewes get skinny. Avoid stress near lambing. Check blood profile with vet.
Metabolic disease (milk fever)
  • Cause: Low blood calcium. May accompany low magnesium and low sugar.
  • Signs: Sheep on ground comatose or dead.
  • Affects: Ewes around lambing, especially older ewes carrying twins.
  • Treatment; Clinicals need urgent Ca injection.
  • Prevention: Ensure good feeding of pregnant ewes and feed calcium supplement well before lambing. Check blood profile with vet,
Metabolic disease (sleepy sickness or twin-lamb disease)
  • Cause: Low blood sugar. May have low magnesium and low calcium also.
  • Signs: Sheep on ground comatose or dead.
  • Affects: Ewes around lambing; especially those carrying twins or triplets.
  • Treatment; Urgent glucose injection.
  • Prevention: Feed sheep well before lambing, especially those carrying multiples, but avoid obesity. Avoid any feed checks which can occur with snowfalls.
Bearings – vaginal prolapse
  • Cause: Reasons not fully known. Overfeeding before lambing.
  • Signs: Large red bag hanging out the rear end of sheep.
  • Affects: Mainly older ewes carrying twins.
  • Treatment: Seek veterinarian advice. Put ewe in safe place and assist urination; Clean bearing before insertion; Use bearing retainer; Cull ewe at end of season.
  • Prevention: Keep sheep active before lambing. Cull ewes that have had bearings and don’t keep their offspring.
Note: Sheep of both sexes can suffer from rectal prolapse which is not such a problem. The often go back in as often as they come out. Cull these sheep.

  • Cause: Bacteria.
  • Signs: Sheep walking with limp and has large, red painful teat and udder.
  • Affects: Milking ewes in the first few weeks after lambing.
  • Treatment: Milk out teat; need antibiotic injection from veterinarian.
  • Prevention: Make sure lambs are milking out both teats, If not, it’s a good idea to milk a teat out for a couple of days.
Clostridial diseases (pulpy kidney, blackleg, black disease)
  • Cause: Bacteria of different species.
  • Signs: Dead sheep which quickly blow up.
  • Affects: Top young lambs.
  • Treatment: No treatment works with clinical cases.
  • Prevention: Correct vaccination programme for farm given to ewes before lambing and to lambs as a booster. Discuss with vet.
Mineral deficiencies – cobalt, selenium, copper, magnesium, iodine
  • Cause: Shortage of specific minerals.
  • Signs: Sheep not thriving, scouring, poor growth and deaths.
  • Affects: Mainly young growing lambs.
  • Treatment: Mineral supplements given by injection for rapid response.
  • Prevention: Blood tests needed for correct diagnosis; Need mineral drenches, injections or dietary supplements (licks).
Scabby mouth
  • Cause: Virus. Can infect humans so is classed as a Zoonotic disease.
  • Signs: Scabs on the lips of young lambs and hoggets.
  • Affects: Young lambs and hoggets.
  • Treatment: Apply disinfectant to lips. Keep away from paddocks with thistles.
  • Prevention: Vaccinate lambs at docking. Don’t graze paddocks with thistles.
Johnes disease
  • Cause: Bacteria.
  • Signs: Animals scour and waste rapidly.
  • Affects: Mainly older ewes.
  • Treatment: None
  • Prevention: Vaccination available.
Facial eczema (FE)
  • Cause: Toxin from fungus growing on dead pasture litter, damages the liver.
  • Signs: Swollen eyes, ears and lips. Sheep are crazy to find shade.
  • Affects: All ages
  • Treatment: Keep in shade. Feed high-energy feed and low protein. Give zinc.
  • Prevention: Be aware of danger periods by doing spore counting. Use zinc supplementation (bolus). Breed sheep with genetics for resistance to FE.
Ryegrass staggers
  • Cause: Toxin from fungus growing in ryegrass seed heads in autumn.
  • Signs: Sheep wobble and fall over when moved.
  • Affects: Al ages.
  • Treatment: Avoid ryegrass pastures. Avoid stress.
  • Prevention: Plant pastures not prone to fungus. Be aware of danger periods. Don’t let pastures go to seed in autumn before grazing.
Poisons –

  • Be able to identify these plants and keep stock away from them. In low concentrations in pastures they are generally not harmful as their intake is diluted with other feed. But when they are dense, then the sheep’s diet may reach toxic levels.
  • Don’t throw prunings into the paddock as sheep often find these plants more palatable after wilting.
  1. Blue lupin (a fungal toxin in lupins can cause lupinosis)
  2. Bracken (Pteridium esculentum)
  3. Devilwood (Ageratina adenophora & A. riparia)
  4. Foxglove (Digitalis purpurea)
  5. Goat’s rue (Galega officinalis)
  6. Hemlock (Conium maculatum)
  7. Jerusalem cherry (Solanum diflorum & S. pseudocapsicum)
  8. Laburnum (Laburnum anagyroides)
  9. Macrocarpa (Cupressus macrocarpa)
  10. Ngaio (Myoporium laetum)
  11. Oak (acorns) (Quercus sp.)
  12. Oleander (Nerium oleander)
  13. Orange cestrum (Cestrum aurantiacum)
  14. Ragwort (Senecio jacobaea)
  15. Rhododendron
  16. Rhubarb. (Rheum x cultorum)
  17. St John’s Wort (Hypericum perforatum)
  18. Tutu (Coriaria arborea)
  19. Yew (Taxus baccata)
  • Overdosing with zinc, copper or selenium.
  • Fertilisers – eaten by stock before being washed in.
  • 1080 poisoning from baits wrongly spread on pastures or stock getting into bush.
  • Overdosing with animal health remedies.

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