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Summer Mastitis – Prevention and Control

10 June 2020
Type Media Article

If you are planning to wean autumn calving suckler cows to reduce grass demand, be aware of the risk of summer mastitis due to current weather conditions. Beef specialist Aidan Murray has advice

Summer mastitis is normally associated with dry cows and heifers during the summer months (late June-mid September). There is no doubt that it has a higher prevalence in some years and under certain conditions.

In 2020 as a consequence of the dry conditions it has been suggested that autumn calving suckler cows should be weaned now to try and cut down on grass demand. This is good advice but you need to be aware that given the current conditions the risk of summer mastitis is a very real one this year. When you think about it you are drying off cows at a time when fly numbers are on the rise.

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

  • Keep dry cows and replacement heifers away from susceptible fields.
  • 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.
  • 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.