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Summer Mastitis – Risk increasing

Summer Mastitis – Risk increasing

Summer mastitis is normally associated with dry cows and heifers in the summer months (late June-mid September). Up to now temperatures have been cool but in the last week conditions became more humid, fly numbers are on the rise, so risk has increased. Aidan Murray, Teagasc Beef Specialist advises

There is no doubt that it has a higher prevalence in some years and under certain conditions.

Apart from animals getting very sick, the potential loss of a quarter, if the animals temperature gets high enough in calf autumn calvers may even abort their calf.

It is caused by a combination of bacteria that work together to give rise to the condition. The main ones are S. dysgalactiae, Peptostreptococcus indolicus and Acranobacterium pyogenes. It is thought to be spread by insects namely the sheep headfly.

Grazing  susceptible animals in fields that are damp with high hedges or near wooded areas can increase the incidence during mild humid weather.


  • Swelling of the teat and infected quarter
  • Frequent kicking as large numbers of flies gather around the teat tip causing irritation to the animal
  • Animals often lie away from the group and will spend more time lying
  • Once on their feet they can show stiffness in the back legs and are reluctant to walk
  • As the condition progresses you can see noticeable weight loss
  • If checked they will often have a high temperature and they run the risk of aborting if they are in calf or are left untreated
  • In severe cases it can be fatal
  • The infected quarter can often eventually burst and the discharge is yellow in colour and foul smelling.


  • Will often depend on how advanced the condition is.
  • Mild cases will be treated with antibiotics and possible use of intramammary tubes
  • More severe cases will also need a course of anti- inflammatory drugs(non steroidal)
  • In all cases the affected quarter needs to by frequently stripped out to reduce toxin build up
  • Some vets will opt to amputate the teat to allow it to drain freely
  • Affected animals should be isolated from the group

Prevention and Control

  • Dry cows should be thoroughly herded at least once a day during the high risk periods. That means going into the field walking through all the cows, any cows lying or away from the group should be got up and udders inspected for any signs of swelling or stiffness when they move.
  • Dry cows that are being fattened off grass will also be at risk. If at all possible it is worth considering having these cows fit for slaughter as early in the summer as you can when the risk period is lower. Fat cows that get summer mastitis will have to be retained longer as they will often lose condition and if they need antibiotic treatment you will have to observe the withdrawal period.
  • Your choice of field for dry cows is important as some fields will suit flies more than others.
  • Fields that are open, dry and kept well topped will reduce the habitat where flies can thrive and so reduce the risk.
  • Some vets may recommend tubing cows at drying off and to tube susceptible pregnant heifers but with the drive to reduce antimicrobial resistance (AMR) this may be a lesser favoured option. In any case if you decide to use intramammary tubes then good hygiene is crucial. Teats should be swabbed pre and post treatment with surgical spirits. The last thing you want to do is to introduce dirt or damage the teat opening or teat canal. Always remember the safety risk when trying to tube cows.
  • Teat seals have also been used to prevent flies from introducing infection through the teat opening. They are usually alcohol based that and give a thin polyurethane covering over the teat. They can be applied by dipping the teat in the solution.
  • Application of Stockholm tar around the teats and udder at least once a week will help to deter flies but it must be frequently applied to be effective.
  • Fly repellents are also used in conjunction with some of the other preventative methods. These usually contain synthetic pyrethroids and will come in the form of a pour-on or in a tag (flectron) that is put into the animals ear. The frequency with which the pour-on is used will depend on the product used.
  • In Scotland farmers that have experienced problems will also make garlic licks available to stock to try and deter flies.
  • In reality you may have to use a combination of techniques to reduce the incidence on your farm.

The Teagasc Beef Specialists issue an article on a topic of interest to Suckler and Beef farmers every Wednesday here on Teagasc Daily. Teagasc provides a Local Advisory and Education service to farmers. Find your local Teagasc office here 


BEEF2022 Open Day

Why not join us for BEEF2022 on Tuesday  5th July in Teagasc Grange, where you can meet with the Teagasc Beef Specialists in person. It is a free event and a day not to be missed!

Further information Beef 2022 Open Day