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Gangrenous mastitis of sheep
Gangrenous mastitis is the most serious form of udder infection in sheep. It mainly occurs in the first weeks of breastfeeding. The bacteria does not just infect the gland: it produces toxins which cut off blood circulation in the udder. Th...
What is it?
Gangrenous mastitis is the most serious form of udder infection in sheep. It mainly occurs in the first weeks of breastfeeding.
The bacteria does not just infect the gland: it produces toxins which cut off blood circulation in the udder. The tissue dies. This is why the udder, initially warm and very hard, then becomes cold and takes on a bluish or purplish tint.
The sheep's life is at stake, not just its udder. The toxins enter the bloodstream and cause shock which can kill her in one or two days.
Key point
A cold, bluish udder is a life-threatening emergency. The ewe can die in one to two days from toxins produced in the udder.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Udder or half of udder very swollen, extremely hard and painful, initially hot.
Ewe which limps in the limb on the affected side, which spreads its hind leg, which refuses to let its lambs suckle.
Modified milk: watery, reddish or brownish, with lumps, sometimes blood, often smelly; or no more milk at all.
High fever at the beginning, then temperature which drops below normal when the condition worsens: this is not an improvement, it is a sign of seriousness.
Udder becomes cold to the touch, skin bluish, purplish then blackish; sometimes fluid under the skin and a clear line between healthy and dead skin.
Slaughtered sheep, no longer eating, isolated from the flock, head lowered, breathing quickly, then lying down without getting up.
Hungry lambs that bleat, hungry lambs that are cold: this is sometimes what alerts you first.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Infection is most often due to staphylococci, particularly Staphylococcus aureus, and certain bacteria producing very destructive toxins, such as Mannheimia haemolytica, present in the mouths of lambs.
The bacteria comes up through the teat canal. The teat is an open door during breastfeeding, especially when it is injured, chapped or irritated by lambs teeth.
An injured udder, soiled bedding, a teat cracked by the cold or by a lamb sucking brutally are enough to open the way.
The toxins produced on site destroy local circulation: this is what distinguishes gangrenous mastitis from ordinary mastitis and explains its seriousness.
First weeks of breastfeeding, the period when the udder works the most.
Teats injured, chapped, bitten or irritated by lambs.
Multiple litters and high demand for milk; sudden weaning or loss of a lamb, which leaves half of the udder unemptied.
Soiled and damp litter, overloaded sheepfold.
Sheep with hanging udder, poorly shaped, dragging on the ground.
History of mastitis: the udder has after-effects and becomes reinfected.
Ewes weakened, poorly nourished, or stressed by transport or batch change.
In dairy farming, insufficient adjustment or maintenance of the milking machine, neglected milking hygiene.
Adoption of lambs from one ewe to another without precaution.
Transmission
Bacteria are transmitted from one ewe to another through the bedding, through the hands, and through the mouths of the lambs, particularly when a lamb successively suckles several ewes.
An affected ewe heavily contaminates its environment: it must be isolated from the rest of the flock.
In dairy farming, the milking machine and the milking order play a major role in the circulation of mastitis germs.
Healthy carrier ewes, without visible signs, maintain the infection in the flock from one year to the next.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
This is a veterinary emergency: call immediately, the ewe can die in one to two days.
The veterinarian assesses the general condition: temperature, heart rate, state of shock, ability to get up. Severity is judged on the whole ewe, not just the udder.
He examines the udder, looks for the edge of dead tissue and altered milk, and determines whether the affected half is salvageable or lost.
A milk sample for analysis allows the bacteria to be identified and herd treatments to be guided, especially if there are several cases.
He also takes care of the lambs, which no longer have milk: it is a parallel emergency, because they are exposed to hypothermia.
In the meantime: isolate the ewe in a quiet, dry place, with water available, and remove the lambs from the affected udder.
Treatment
Treatment is urgent and is twofold: to fight the infection and to support the sheep against a state of shock.
The veterinarian sets up general antibiotic therapy and supportive care, particularly against pain, inflammation and dehydration. A sheep in shock needs to be supported above all.
Milking the affected udder may be indicated in certain situations to evacuate toxins, but it is up to the veterinarian to say: on an already necrotic udder, it is useless and painful.
When part of the udder is dead, it eventually becomes detached; the veterinarian can decide on surgical intervention or support for this evolution, which is long and requires care.
If the ewe is too affected, euthanasia is sometimes the most respectful decision: the veterinarian will help you judge this.
The lambs must be taken care of immediately: put up for adoption on another ewe or artificially breast-fed, according to the veterinarian's advice.
No mastitis treatment should be repeated from one ewe to another or from one year to another without advice: the wrong product wastes the hours that count.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Check the sheep's udder regularly during breastfeeding, particularly in the first weeks: a hard or hot udder detected early prevents gangrene.
Check the condition of the teats and treat cracks and wounds.
Clean, dry and abundant litter; not overloaded sheepfold.
Avoid sudden weaning and monitor ewes that lose a lamb: half of the udder not emptied is a classic starting point.
Immediately isolate any suspect sheep from the rest of the flock.
Wash your hands between two sheep, do not pass from a sick udder to a healthy udder.
Avoid suckling the same lamb on several ewes.
Cull ewes with damaged udders or those that have already had serious mastitis: they remain a source of infection.
In dairy farming, maintain and check the milking machine, respect hygiene and milking order, treat mastitis at the end of lactation according to the veterinarian's protocol.
Feed lactating ewes well, especially those nursing multiple lambs.
Possible complications
Death of the sheep from toxic shock, often within one to two days.
Permanent loss of the affected half of the udder, which becomes detached; open wound to be treated for a long time.
Generalized infection, distant abscess.
Death or weakening of lambs deprived of milk, exposed to hypothermia and infections.
Ewe definitely unfit to breastfeed, therefore to be culled.
Maintenance of infection in the flock if the ewe is not isolated and if the udders are not checked.
When to see a veterinarian
Your ewe's udder is very hard, swollen and painful: call the same day.
It is cold, bluish or purplish: absolute emergency, the life of the sheep is at stake.
The milk is watery, red, brown, lumpy or smelly, or there is no milk left.
The ewe limps, refuses to let its lambs suckle, isolates itself, no longer eats.
She has a fever, then becomes cold and doesn't get up again.
Their lambs are bleating, hungry or cold: take care of them at the same time as their mother.
Prognosis
The prognosis depends on the time frame. Mastitis caught in the first hours, before necrosis, can be controlled, even if the milk production of the affected half is often lost.
As soon as the udder is cold and bluish, the life of the ewe is at stake and the affected tissue cannot recover.
A surviving ewe most often remains unable to breastfeed properly: culling is the rule.
Lambs almost always escape if they are taken care of immediately.
Frequently asked questions
Why does the udder become cold when it was an infection?
Because the toxins produced by the bacteria block blood circulation in the udder. The tissue deprived of blood dies: it cools and takes on a bluish tint. The change from hot to cold is a sign of worsening, never of improvement.
Should we continue to milk the affected udder?
Only if your veterinarian indicates so. In some cases it helps flush out toxins; on an already necrotic udder it is useless and very painful. Don't decide alone.
What to do with the lambs?
They must be taken care of immediately, in parallel with caring for the mother: they no longer have milk and are cooling down quickly. Your veterinarian will direct you towards adoption by another ewe or towards artificial breastfeeding.
Will the ewe be able to nurse next year?
The destroyed part of the udder does not grow back. A ewe that has had gangrenous mastitis is generally culled: it breastfeeds poorly and remains a source of contamination for the flock.
How to spot mastitis before it becomes serious?
By regularly feeling the udder of lactating ewes and looking at the teats. A ewe that is lame, refuses to suckle or has half of its udder hard must be examined the same day.
References
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 10 August 2026
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