Mastitis in dairy cows

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is the inflammation of the mammary gland and udder tissue, and is a major endemic disease of dairy cattle. It usually occurs as an immune response to bacterial invasion of the teat canal by variety of bacterial sources present on the farm, and can also occur as a result of chemical, mechanical, or thermal injury to the cow's udder.


Milk-secreting tissues and various ducts throughout the udder can be damaged by bacterial toxins, and sometimes permanent damage to the udder occurs. Severe acute cases can be fatal, but even in cows that recover there may be consequences for the rest of the lactation and subsequent lactations.

The illness is in most respects a very complex disease, affected by a variety of factors: it can be present in a herd subclinically, where few, if any, symptoms are present in most cows. Practices such as close attention to milking hygiene, the culling of chronically-infected cows, good housing management and effective dairy cattle nutrition to promote good cow health are essential in helping to control herd mastitis levels.

Mastitis is most often transmitted by contact with the milking machine, and through contaminated hands or other materials, in housing, bedding and other equipment. During the 1960s, a five-point plan was devised by the National Institute for Research into Dairying, aimed at providing a strategy for the reduction and control of mastitis at farm level, which in adapted form is still followed today.

Mastitis treatment and control is one of the largest costs to the dairy industry in the UK, and is also a significant factor in dairy cow welfare. Losses arise from:

  • Milk thrown away due to contamination by medication or being unfit to drink.
  • A reduction in yields due to illness and any permanent damage to udder tissue.
  • The extra labour required to tend to mastitic cows.
  • The costs of veterinary care and medicines.
  • The cost of reduced longevity due to premature culling.

Organic dairy farmers, having limited use of antibiotic treatments, often use alternative therapies such as homeopathy for the treatment of mastitis and adopt a more holistic approach to mastitis prevention; this concept of a wide-ranging approach to mastitis control forms the backbone of the AHDB Dairy Mastitis Control Plan.

The AHDB Dairy Mastitis Control Plan

Whilst mastitis in cattle is well controlled in an historical context, there has been much debate about its apparent resurgence in recent years. In view of these recent changes, and the lack of a structured, co-ordinated approach to understanding and solving mastitis problems in dairy herds, it was felt that there was a need to modify the industry's approach to mastitis control to encapsulate a diagnosis and a whole farm approach.

AHDB Dairy launched the AHDB Dairy Mastitis Control Plan, a bespoke plan for individual farms depending on the farm's own circumstances. A detailed survey of the farm is undertaken along with analysing milk bacteriology, disease patterns from monthly milk recording, somatic cell count data and clinical mastitis information. From the interpretation of this information, the farm is given a plan to combat mastitis. This is then reviewed on a regular basis as it takes time from implementation of the plan to see success. Trial work showing full compliance with the advice resulted in a 36% reduction in mastitis, with two thirds compliance with the advice resulting in a 20% reduction in mastitis.

The AHDB Dairy Mastitis Control Plan

Pathogens implicated in the causes of mastitis

The effects of mastitis on the dairy cow

The farm environment and the causes of mastitis

Recording and diagnosing mastitis