Sheep are resilient animals but, like all livestock, they hide the early signs of illness instinctively — a behaviour that evolved to avoid appearing vulnerable to predators. By the time an animal is showing obvious distress, the disease has often been present and progressing for days. Developing sharp observational skills during daily checks, and knowing specifically what to look for, is one of the most valuable skills a livestock keeper can develop.

This guide covers the most common and most important warning signs in sheep in Australian conditions. None of these signs is a diagnosis — they are indicators that require closer assessment, possibly veterinary advice, and prompt action.

1. Wool break and fleece deterioration

A localised break in the wool staple — where the fibre has weakened and fractured at a specific point — indicates a period of significant stress or illness approximately the number of months before the break that corresponds to how far down the staple the break sits (wool grows approximately 1 cm per month). A mob-wide wool break is a sign of a flock-level stress event. In individual animals, it often indicates a preceding illness episode that went unnoticed.

2. Separation from the mob and dullness

A sheep standing apart from the mob, head down, with a dull eye and a hunched posture is the single most reliable early indicator of illness in a species that otherwise hides disease signs well. Check these animals immediately — do not assume the animal will 'come good' without intervention.

3. Scouring and dag

Persistent scouring (diarrhoea) in sheep is most commonly caused by internal parasites, particularly barber's pole worm in warm, wet conditions and small brown stomach worm in cooler seasons. It can also indicate bacterial gastroenteritis, coccidiosis in lambs, or Johne's disease in adults. Always check FAMACHA scores in scouring mobs.

4. Pale FAMACHA scores

FAMACHA assessment — matching the colour of the inner lower eyelid to the FAMACHA chart — is the most practical on-farm tool for assessing barber's pole worm burden without egg counting. A score of 4 or 5 (pale pink to white) indicates anaemia and requires immediate drenching. Scores of 3 in multiple animals indicate the mob is at risk and monitoring should intensify.

5. Bottle jaw (submandibular oedema)

A soft, fluid-filled swelling under the jaw — bottle jaw — is a sign of severe protein loss, usually from heavy parasite burden causing gastrointestinal damage and protein-losing enteropathy. It is a late sign of serious disease. Animals with bottle jaw require immediate drenching (with a product effective against the local parasite population — check recent egg count reduction test data) and supportive care.

6. Lameness and foot problems

Footrot is the most economically significant cause of lameness in Australian sheep, caused by Dichelobacter nodosus in wet conditions. It produces a characteristic foul-smelling infection between the claws with underrunning of the hoof horn. Foot scald (a milder interdigital infection) and foot abscess are also common. All lame sheep require close foot examination and appropriate treatment.

7. Respiratory signs

Coughing, nasal discharge, laboured breathing, and fever in sheep suggest respiratory infection — ovine respiratory disease complex (ORDC) involves multiple viral and bacterial pathogens. Pneumonia in lambs is a significant cause of pre-weaning mortality. Pulpy kidney (enterotoxaemia) can also present with sudden death or acute neurological signs in unvaccinated sheep.

8. Pregnancy toxaemia (twin lamb disease)

Pregnant ewes carrying multiple lambs in the last 4 to 6 weeks before lambing can develop pregnancy toxaemia — a metabolic condition caused by inadequate energy supply relative to the demands of late pregnancy. Signs include depression, apparent blindness, star-gazing, muscle twitching, and recumbency. Prevention (adequate nutrition through late pregnancy) is far more effective than treatment; once neurological signs develop, prognosis is poor.

9. Flystrike

Maggot infestation of the wool — particularly in dag-soiled wool around the breech and along the back in wet conditions — can progress from small areas to life-threatening infestations within 24 hours in warm weather. Inspect frequently in warm, wet periods; any sheep with a wet, brown stain on the fleece or a distinctive sweet-fetid smell should be checked immediately for fly strike.

10. Sudden death

Sudden death with no prior obvious signs in Australian sheep most commonly indicates pulpy kidney (enterotoxaemia, caused by Clostridium perfringens type D in unvaccinated animals on lush feed), blackleg, or other clostridial disease. A mob-level sudden death event warrants post-mortem examination and urgent veterinary consultation. Vaccination with 6-in-1 (clostridial) prevents most of these losses.

When to call a vet

Any single animal showing multiple symptoms simultaneously, any situation involving multiple animals affected at once, any sign of neurological involvement (incoordination, circling, seizures), or any rapidly deteriorating animal should prompt immediate veterinary contact. Do not wait to see if the animal improves — the time lost in delay is frequently the margin between a treatable problem and a dead animal. Keep your vet's contact number saved in your phone and know the after-hours emergency number before you have an emergency.

For more on sheep health, see our Health Guide and FAQ page.

For more, see our Sick Pig Symptoms: Warning Signs Every Australian Pig Keeper Should Know and Australian Sheep Breeds: Complete Guide to the Most Important Breeds for Australian Conditions.