Bovis ISSN 2398-2993

Mastitis: approach to the herd mastitis problem

Contributor(s): James Breen , Alexander Corbishley

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Fundamental Concepts

  • The approach to a dairy herd with a mastitis 'problem' will be similar whether the problem is one of a perceived or confirmed increase in clinical mastitis rate or an increase in herd Somatic cell count (SCC).
  • In both cases the starting point is to understand the EPIDEMIOLOGY rather than the etiology:- too often milk samples are collected and submitted for bacteriology, some bacterial pathogens are isolated and the epidemiology is inferred rather than analysed from data.
  • Instead, clinical mastitis records and SCC data are used to make a herd diagnosis by understanding the PATTERN of new cases and/or new infections through a lactation cycle, during the year, between groups and parities etc.
  • A fundamental area to understand with any herd is WHEN new clinical cases and/or new infections as measured by SCC occur during the lactation cycle (regardless of etiology), and in particular differentiating herds where infections are predominantly acquired during the dry period or are mostly occurring during lactation. During the first three years of the AHDB Dairy Mastitis Control Plan, ~45% of herds were characterized as having predominantly DRY PERIOD infection patterns.
  • Herds can then be categorized as those where infections are predominantly acquired from the environment or a significant proportion of infection is acquired from other infected cows ('contagious' mastitis; transmission from an infected cow to an uninfected cow). The former is much more common in the modern UK dairy herd, and typically accounts for ~90% of mastitis patterns.
  • Patterns through the year are also very important to understand - seasonality in new clinical case rate and/or rates of new SCC infection will highlight environmental infection patterns and the importance of winter housing, management of cows at pasture etc.
  • The epidemiology should be further explored by restricting the analysis of clinical mastitis and SCC data to different groups (eg the rate of new SCC infection in cows in early lactation) and different parities (eg the impact of 1st lactation heifers on the rate of new clinical mastitis cases).
  • Finally, samples should be collected from cases of clinical mastitis or high SCC cows to confirm the etiology and further refine the diagnosis.
  • Understanding the HERD mastitis diagnosis in this structured way informs the veterinary advisor on the likely area(s) to target in terms of control.
    • For example, there is little to be gained from advising a herd to improve the pre-milking routine when 80% of new clinical cases are arising from infections acquire during the dry period - UK research clearly shows a targeted approach works.
  • Importantly, a focus on treatment is NOT the answer for herds with clinical mastitis and/or high SCC issues, and so whilst there may be occasions where we need to work with clients to ensure cure rates are optimized (particularly during the dry period), reducing the rate of new infection in dairy herds is rarely achieved through use of antibiotic treatment.

What You Need to Achieve a Herd Diagnosis

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The Herd with an Increased Clinical Mastitis Rate

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The Herd with an Increased Somatic Cell Count

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Getting the Most from Bacteriology Data

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Herd Diagnosis...and Control

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMed Resource.
  • Down P M, Bradley A J, Breen J E, Hudson C D & Green M J (2016) Current management practices and interventions prioritised as part of a nationwide mastitis control plan. Vet Rec 178 (18), 449 PubMed.
  • Green M J, Leach K A, Breen J E, Green L E & Bradley A J (2007) National intervention study of mastitis control in dairy herds in England and Wales. Vet Rec 160, 287-293 PubMed.
  • Bradley A J & Green M J (2005) Use and interpretation of somatic cell count data in dairy cows. In Practice 27, 310-315.
  • Green M J, Green L E, Medley G F, Schukken Y H & Bradley A J (2002) Influence of Dry Period Bacterial Intramammary Infection on Clinical Mastitis in Dairy Cows. J Dairy Sci 85, 2589-2599 PubMed.

Other sources of information

  • Bradey et al (2012) Mastitis Control Plan 3 year report (2008-2012). [online] Available at: https://dairy.ahdb.org.uk. Last accessed 16th April 2018.

Organisation(s)

  • School of Veterinary Medicine & Science, University of Nottingham.


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