Disease Facts - Mastitis and milk quality

Mastitis is the most common infectious disease of dairy cattle. Clinical mastitis can be recognised from abnormal milk (clots, flakes and discolouration) or by effects on the cow (increased temperature, lowered milk yield, or pain and discomfort).

Mastitis costs UK farmers £100M - £400M a year

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Several species of bacteria can cause mastitis, and these can be spread in different ways:

Spread via the environment
Streptococcus uberis
Escherichia coli

Spread by contact
Staphylococcus aureus
Streptococcus dysgalactiae
Streptococcus agalactiae

The bacteria that cause contagious mastitis are now largely controlled by good hygiene, those that are spread via the environment are more of a problem.

UK dairy farmers have had considerable success in controlling mastitis by following the five-point plan, that has been developed through years of research. This simple, yet effective, approach has reduced the rate of clinical mastitis by 75%. However, despite all this good practice, there are still around 1,000,000 cases of clinical mastitis every year in the UK herd of 2,500,000 cows.

one million cases of clinical mastitis occur in the UK every year

Mastitis Control - the 5-point plan

  1. Teat dip all cows after every milking
  2. Use dry cow treatment on all cows that remain in the herd
  3. Cull persistently infected cows
  4. Make sure that the milking machine works properly
  5. Treat all cases

Obviously, better attention to detail may reduce this further. But even the development of vaccines against the more common types of mastitis will not eradicate the problem. It is estimated that with such improvements, up to 500,000 cases will still occur each year.

Fast, effective treatment is the key

In order to safeguard animal welfare, milk quality and the farmer's income, mastitis cases must be identified early and treated quickly and effectively. Research at the IAH indicates that effective use of antibiotics is an essential part of mastitis control. But even when 90% of animals are clinically cured only 60% of cases show a bacteriological cure. However when coupled with early detection, the effectiveness of antibiotics usually exceeds 95% bacteriological cure. This results in:

  1. Fewer clinical cases
  2. Less pain
  3. Reduced recurrence
  4. Less antibiotic used overall
  5. Earlier return to production

Prospects for the future

The usefulness of antibiotics in agriculture is in constant jeopardy through the emergence of drug-resistant bacteria. Because of this threat, the Institute for Animal Health is working on two fronts, which avoid this issue:

In the medium term:
Developing vaccines
In the longer term:
Identifying cattle resistant to mastitis