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Mastitis (Sheep)

Mastitis is an inflammation of the ewe’s udder and is usually caused by bacterial infection.  It is a significant ewe health and welfare problem for both dairy and meat sheep farmers worldwide. Mastitis can also result in significant economic losses.

For the ewe, the inflammation and swelling of the udder is acutely painful and the toxins produced by the bacteria can make her feel ill, inappetant and even kill her.  As the damage caused to the udder is often permanent and results in decreased milk production, mastitis is also associated with premature ewe culling.  Mastitis impacts on lamb welfare as the reduction in milk production, milk fat and milk protein lead to reduced lamb growth and higher risk of lamb mortality.

In UK lowland flocks, acute mastitis affects between 4-5% of ewes each year and in hill flocks, it affects 1-2% of ewes.  Chronic mastitis is estimated to affect between 1-15% of ewes.

Key Points

  • Acute mastitis affects between 4-5% of lowland ewes and 1-2% of hill ewes each year.  Chronic mastitis affects between 1-15% of ewes.
  • Ewe mastitis has important impacts on ewe mortality, premature ewe culling, lamb mortality and growth.
  • Mastitis can be peracute, acute, chronic and clinical or sub-clinical depending on the severity and duration of clinical signs in the ewe.
  • The main risk period for clinical mastitis is the first week post lambing to around peak lactation at 3-4 weeks post lambing.
  • The most common bacteria found in mastitis cases are Staphylococcus aureus and Mannhaemia haemolytica, although other bacteria may occur.
  • The bacteria enter the udder through the teat canal, some are transferred from the lambs’ mouths when sucking.
  • Factors which damage the ewes’ teats, e.g. chapping, orf or excess sucking by hungry lambs, increase the risk of a ewe developing mastitis.
  • Ewes feeding 3 or more lambs are at increased risk of mastitis.
  • Treatment of ewes with mastitis should be prompt and is aimed at saving the ewe’s life as damage to the udder can be permanent.
  • Ewes chronically affected by mastitis should be culled.
  • All ewes’ udders should be inspected at weaning and at the pre-tupping check.
  • Preventative strategies for mastitis should be discussed with your vet as part of your health planning for the flock.  Consideration should be given to ewe and lamb nutrition pre and post lambing, maintaining good ewe teat condition, and environmental hygiene.
  • The viral infection Maedi-Visna can cause chronic mastitis in sheep and requires a separate approach.

Research at Moredun

Moredun have a research interest in novel vaccine candidates and approaches for protection of sheep against mastitis.

Farming and Veterinary Outreach

For further Information about Mastitis please see Moredun Newssheet 6.4 – Mastitis in Sheep:

  • If you are a Moredun Member you can view this online by signing in to the Member Portal

For non-members you can request a copy by contacting The Moredun Communications Team