Early Signs of Illness in Dairy Sheep

By Dr Duncan Houston

A dairy ewe may still walk into the parlour, eat some feed and produce milk while a health problem is developing. The first clue might be a small yield drop, a change in milking behaviour or an udder half that feels different.

Daily milking gives you regular opportunities to notice these changes. Records and milk testing add another layer, especially for problems that cannot be detected by looking at the ewe.

The goal is to recognise changes early enough to investigate, support the ewe and protect milk quality. No observation routine catches every illness before signs appear.

Quick Answer

Early signs of illness in dairy sheep include unexplained reductions in milk yield, rising somatic cell counts, altered udder texture, reduced appetite, condition loss and changes in movement or milking behaviour. Check the whole ewe as well as both udder halves, and compare findings with her normal pattern and stage of lactation. Abnormal milk or a painful udder needs prompt veterinary advice, while collapse, severe breathing difficulty or a cold, discoloured udder requires immediate attention.

1. Milk production drops without a clear explanation

Compare each ewe with her own recent output. A flock average can look acceptable while several individuals are declining.

Record days since lambing, milking frequency and whether lambs still have access to the ewe. Milk collected in the parlour is not necessarily her total production when lambs are also suckling.

Yield changes with lactation stage, nutrition, season and milking management, so a lower figure does not automatically mean disease. An abrupt or persistent unexplained drop deserves investigation.

A useful first distinction is:

• One ewe affected: Check her udder, appetite, feet, condition and recent health history.

• Several ewes affected together: Check water supply, feed delivery, heat exposure, equipment and changes in routine alongside possible disease.

Do not automatically increase grain before checking why production has fallen.

2. The udder or milk changes slightly

A ewe has two udder halves. Examine both, even when only one appears to be producing less.

Look for new differences in size, warmth, firmness or tenderness. Check for teat injuries, swelling, lumps or an udder half that remains unusually full after milking.

When checking foremilk under your dairy’s hygiene protocol, watch for flakes, clots, unusual wateriness, blood or discolouration. These are reasons to investigate, even if the ewe still seems bright.

A New Zealand study of dairy ewes found that uneven glands, swelling and clots were common features of clinical mastitis. Many affected ewes did not have obvious systemic illness, so waiting for fever or severe dullness would miss cases.

Keep visibly abnormal milk out of the supply and seek same-day veterinary advice. The examination and treatment plan should address the ewe’s comfort and general health as well as her udder.

3. Somatic cell counts rise while everything looks normal

Subclinical mastitis causes inflammation without obvious clinical changes in the milk or udder. Testing is therefore central to finding it.

Useful tools include:

• Individual ewe somatic cell counts, or SCC.

• Testing each udder half with the California Mastitis Test, also called a rapid mastitis test.

• Laboratory culture of appropriately collected milk samples.

SCC and rapid tests help identify inflammation. They do not identify the organism or automatically tell you which treatment is needed. Recent research in grazing dairy ewes supports using these tests alongside milk culture and flock context.

Interpret results with your vet using sheep-specific guidance. Early lactation and colostrum require particular care, and different organisms can produce different cell-count responses. Avoid importing a cattle or goat threshold as a universal diagnostic rule for sheep.

Bulk-tank SCC helps monitor flock udder health, but it cannot identify the affected ewe. A reassuring tank result also does not prove every udder is healthy. Individual testing is needed to investigate suspect animals.

4. Feeding slows and body condition begins to slip

Watch for a ewe that arrives at feed but eats little, sorts through the ration, grazes less or spends less time chewing her cud.

Check the practical details: working troughs, adequate flow, clean water, feed quality and enough space for less dominant ewes. Feed being available does not guarantee that every ewe consumes enough.

Milk production places substantial demands on nutrition. However, continued or rapid condition loss should not simply be accepted as the price of a good milker.

Feel over the loin, backbone and short ribs to assess condition beneath the fleece. Use consistent scoring and compare changes over time. A full fleece is rather good at keeping secrets.

Poor intake or condition loss can reflect inadequate feeding, dental problems, parasites, pain or chronic disease. The ration and the ewe both need checking.

5. Milking behaviour or walking changes

A ewe that normally enters calmly may begin hanging back, shifting her weight, kicking at the cluster or resisting touch.

Check for udder discomfort and teat injury, but also inspect footing, restraint, handling and milking equipment. Incorrect machine function can cause discomfort and interfere with milking. A first-lactation ewe may need patient familiarisation, while a new change in an experienced ewe deserves investigation.

Shortened strides, kneeling to graze or lagging behind can indicate painful feet. Lameness can reduce feeding and contribute to condition loss. Examine affected sheep promptly rather than waiting for them to stop bearing weight.

6. Droppings, eyelid colour or skin change

Repeated scours, increasing dags or weight loss should trigger investigation of parasites, feeding and other intestinal disease.

A clean tail does not rule out worms. Barber’s pole worm can cause anaemia without diarrhoea. Pale inner lower eyelids, weakness or swelling beneath the jaw need prompt attention and may indicate disease that is already significant.

Use worm testing and a regional parasite plan rather than repeatedly drenching every ewe whose milk drops.

Also inspect sheep that stamp, bite at their fleece or develop a damp, dark patch. Flystrike can be hidden beneath the wool and needs immediate inspection and prompt treatment.

7. Breathing or resting behaviour changes

Check breathing before moving sheep into the parlour. Repeated coughing, nasal discharge or increased breathing effort at rest warrants attention.

Heat can change feeding, resting and breathing patterns. Shade, reliable water and suitable ventilation matter, particularly when sheep wait in collecting areas. Avoid unnecessary handling during hot conditions.

Do not assume heat explains marked respiratory effort or a ewe that remains distressed after resting. Severe or open-mouth breathing at rest requires urgent veterinary help.

Recently lambed ewes need extra attention

Record the lambing date and any difficult delivery, retained membranes or assisted birth.

After lambing, reduced appetite, dullness and foul-smelling discharge can indicate uterine infection. The ewe may also become reluctant to nurse. These findings need prompt assessment.

Before lambing, reduced interest in feed, isolation and increasing dullness can be early signs of pregnancy toxaemia, especially in ewes carrying multiple lambs. Do not wait until the ewe is down.

Hypocalcaemia, often called milk fever, can occur before or after lambing in sheep. Stiffness, unsteadiness, weakness and reduced rumen activity are concerning, and hypocalcaemia can occur alongside pregnancy toxaemia. Timing and blood testing help your vet distinguish these problems.

If lambs are still suckling, monitor them too. Persistent hunger or poor growth can reveal inadequate milk supply, including from maternal mastitis.

How urgently should you act?

What you notice	Recommended action
One small yield change, with a bright ewe, normal appetite and no udder or milk abnormalities	Check records, suckling access, feed, water and equipment now. Recheck at the next milking; investigate if the change persists or worsens.
Repeated unexplained yield decline, rising individual SCC or gradual condition loss	Arrange veterinary investigation and appropriate testing promptly. Do not wait for visible illness.
Abnormal milk, a hot or painful udder, persistent poor appetite, lameness or illness around lambing	Seek same-day veterinary advice. Exclude abnormal milk from the supply.
Collapse, inability to stand, severe breathing difficulty, neurological signs or a cold, discoloured udder	Contact a vet immediately. Minimise handling while help is arranged.

A sudden problem affecting several ewes, an unexpected death or rapid deterioration increases urgency.

What else could explain reduced milk production?

Mastitis is one possibility, but your vet will also consider inadequate intake, water restriction, heat stress, lameness, digestive disease, reproductive complications and chronic illness.

Milk collection can change because of altered suckling, milking intervals or equipment performance. These management explanations still need correcting.

The investigation may include an examination, separate samples from each udder half, blood or faecal testing, ration assessment and a machine check. A milk-yield alert is a reason to examine the ewe, not a diagnosis.

When is this an emergency?

Call your vet immediately if a ewe:

• Collapses, cannot rise or becomes rapidly weaker.

• Has severe breathing difficulty.

• Develops marked abdominal swelling with distress.

• Shows seizures, severe unsteadiness, circling or apparent blindness.

• Has a severely painful udder together with marked dullness or weakness.

• Develops a cold, blue, purple or darkened udder.

A cold, discoloured udder can indicate severe mastitis with compromised blood supply. It is not a reassuring sign that inflammation has settled.

Provide a quiet, sheltered area and avoid forcing a weak ewe to walk. Do not force oral fluids or drenches into an animal that cannot swallow safely.

A practical checking plan

1. Identify the ewe and the change. Record her identification, days in milk, yield trend, appetite, udder findings and recent treatments.

2. Observe before handling. Watch breathing, movement, interaction with the flock and actual feeding.

3. Examine the whole ewe. Check both udder halves, teats, feet, condition and droppings. Take a rectal temperature if trained, and interpret it with the other findings.

4. Protect the milk supply. Clearly identify suspect and treated ewes. Follow your dairy’s separation, milking-order and equipment hygiene procedures.

5. Discuss sampling before treatment. Where practical, collect milk samples using your vet’s sterile sampling instructions before antibiotics. Do not delay emergency treatment to obtain samples.

6. Agree on follow-up. Set a recheck time and monitor appetite, comfort, milk appearance and production. Escalate if the ewe deteriorates or fails to improve as expected.

Continue milking or manage drying off according to the veterinary plan. Simply missing milkings can leave a ewe with an uncomfortably distended udder.

Milk withholding needs a sheep-specific plan

Before using any medicine, drench or external parasite treatment, check whether it is suitable for sheep producing milk for human consumption. Some labels exclude these animals entirely.

Record the product, dose, route and last treatment time, together with the authorised milk withholding instructions. Milk withholding applies to milk from the whole ewe. Meat withholding and milk withholding are separate requirements.

Do not copy a dairy-cow dose or milk withholding period onto a ewe. Research has demonstrated that residues from some cattle mastitis products can persist differently in sheep milk. Your prescribing vet must determine an appropriate, lawful treatment and withholding plan.

Normal-looking milk does not establish that residues have cleared. Keep withheld milk out of the tank and processing supply, and ask your vet about disposal or any proposed use for feeding lambs.

Common mistakes to avoid

• Waiting for obvious udder swelling. Subclinical disease needs testing.

• Using the tank average to clear every ewe. Individual problems can be hidden.

• Calling kicking a temperament issue. Pain and equipment problems deserve a check.

• Giving extra grain or repeated drenches without investigating. Neither addresses every cause of reduced yield.

• Returning milk to the tank because it looks normal. Clinical improvement and completion of withholding are separate decisions.

Prevent problems between milkings

Maintain clean, dry resting areas, hygienic teat preparation, appropriate post-milking teat care and properly serviced equipment. Use clean gloves and individual drying materials, and train everyone to recognise abnormal milk and udder changes.

Match feeding to pregnancy and lactation, monitor body condition, introduce ration changes gradually and maintain foot and parasite programmes. Plan weaning and drying off with your vet, including management of recurrent udder problems.

For feeding guidance, see Dairy Sheep Feed: What It Contains and How to Choose the Right Diet.

Can dairy sheep have mastitis with normal-looking milk?

Yes. Subclinical mastitis can occur without visible abnormalities. Individual milk testing and appropriate culture help investigate it.

Does a high somatic cell count always mean antibiotics are needed?

No. It is a finding to interpret alongside repeated results, lactation stage, examination and culture. Your vet should decide whether treatment or another management response is appropriate.

Can an acceptable bulk-tank SCC hide an infected ewe?

Yes. Tank results describe pooled milk. They cannot confirm that every ewe or udder half is healthy.

Will milk production return after illness?

It may recover, but the outcome depends on the cause, severity and udder damage. Some ewes retain reduced production or chronic udder changes after mastitis, so follow-up should assess comfort, milk quality and future suitability for milking.

ASK A VET™ can help you organise changes in milk production, feeding and behaviour into useful questions for your flock veterinarian. Small changes deserve attention, and a ewe showing emergency signs needs immediate local veterinary care.