My approach to reducing clinical mastitis

This is the first of two articles on approaches to reducing clinical mastitis and somatic cell counts that this author has used for many years. It has proved successful provided the farmer engages in the process. Of course, there are other successful approaches that can be taken. This article will not discuss Mycoplasma or Prototheca mastitis.


Clinical mastitis should be reduced for many reasons; improving animal welfare as it is a very painful condition, reduce medicine use especially antibiotics, protect milk quality (somatic cell count, Bactoscan and medicine residues) and for economic reasons as mastitis is an expensive disease.

There are many dairy herds that have low levels of clinical mastitis. Mastitis can be measured using the percent of the herd affected per month or the mastitis rate which is the number of cases per 100 cows per year where one case is one quarter infected once. This author prefers the mastitis rate as an easy way to quantify disease.

Some herds with excellent management have a mastitis rate as low as 10 to 15. The target is often quoted as 30. Targets should be set for individual herds and based on what is an acceptable and achievable level of disease.

There are many herds that still have high mastitis rates and may not be aware that this is a problem especially if their mastitis data is not analysed. Some farmers accept higher rates while others are constantly looking at ways to reduce incidence.

Mastitis cases by days in milk. There were over 500 cases in the first 7 days after calving
Mastitis cases by month, black arrows are times of heat stress

Causes of mastitis – Mastitis can be broken down into various categories;

  • clinical and subclinical
  • Contagious and environmental
  • Lactation period infections (LPI) and dry period infections (DPI)

Clinical mastitis is mainly caused by environmental mastitis, such as coliforms and Streptococcus uberis. Staphylococcus aureus can cause clinical mastitis, but the importance of the environmental bacteria has increased. Levels of Staph. aureus and other contagious bacteria have decreased as dairy companies require lower cell counts.

The environment is the reservoir of infection with environmental mastitis. Infection can be transferred onto the teats at three different times;

  1. Between milkings if the cows are lying in dirty conditions or have faecal splashing up against teats after coming out of the parlour
  2. During milking if there is poor teat preparation or poor hygiene
  3. During the dry period

Coliform infections mainly cause clinical mastitis while Strep. uberis causes both clinical and subclinical mastitis. Both can cause lactation and dry period infections. Staph. aureus is contagious, causes clinical and subclinical mastitis and enters only during lactation.

Practical steps to control clinical mastitis

  1. Accurate diagnosis of the cause of clinical mastitis
  2. Review current mastitis management
  3. Agree and implement a control plan
  4. Monitor and review progress

1. Accurate diagnosis of the cause of clinical mastitis

Individual farms can have a combination of mastitis problems. It is essential that the specific mastitis problem is properly identified. This requires data analysis and bacteriology testing. This approach is no different to a modern motor car being plugged into a computer at the garage to a precise diagnosis of an engine problem.

Most progressive dairy farmers keep computerised records allowing in-depth analysis at the touch of a button. It’s advisable to check accuracy of records as if these are incomplete then data analysis could

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