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Mastitis in ewes

Mastitis in ewes

Mastitis in ewes can be fatal and usually results in the end of her productive life.

The usual presentation is acute gangrenous mastitis (blue or black bag) usually caused by either Staphylococcus Aureus or Mannheimia Haemolytica. S. Aureus is normally present on the teat skin but damage to the teat ends allows it access into the teat canal and causes mastitis.

M. Haemolytica is present in the tonsils of lambs so colonises the udder during suckling. The bacteria produces toxins which prevent blood flow and cause the udder to turn blue/black hence the name. This often occurs around peak lactation (three to six weeks post-lambing) and the initial clinical signs may be as subtle as a ewe looking lame or a lamb bleating because it’s hungry. The disease then rapidly progresses.


The risk factors include:

  • Under feeding ewes round lambing or ewes in poor condition, as lambs to these ewes will cross suckle or create teat lesions by over suckling.
  • Damaged teat end or Orf on teats
  • Lumps in the udder
  • Lambing inside (the longer the time spent inside the greater the risk of developing mastitis)
  • Dirty, wet pens and dirty hands when handling udder/ underneath of sheep
  • Harsh, cold weather

Treatment is unlikely to save the udder but may save the ewe’s life:

  • Remove lambs from the ewe and ideally artificially rear as rearing these lambs on another ewe may spread the mastitis
  • Antibiotic injectable AND non-steroidal anti-inflammatory such as Loxicom
  • A ewe that has had mastitis will be more likely to get fly strike so preventative fly treatment is essential.
  • There is a vaccine against S. Aureus available; VIMCO. This has to be given three and five weeks pre-lambing. Most of the trial work has been done in dairy ewes and it is licenced to reduce to the incidence of subclinical mastitis. Potentially this could also help to reduce the incidence and severity of black bag in your flock however at the moment there is limited evidence to prove this.

If you have any questions regarding mastitis in your flock, please contact our Farm Vet Team.